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Effects of Preharvest Electrolyte Supplementation on the Hydration and Meat Quality of Cull Dairy Cows

Permanent Link: http://ufdc.ufl.edu/UFE0041905/00001

Material Information

Title: Effects of Preharvest Electrolyte Supplementation on the Hydration and Meat Quality of Cull Dairy Cows
Physical Description: 1 online resource (75 p.)
Language: english
Creator: Arp, Travis
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: electrolyte, hydration, meat, stress
Animal Sciences -- Dissertations, Academic -- UF
Genre: Animal Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Transportation and handling of cattle prior to slaughter are stressors which can impact weight change and postmortem muscle quality. Electrolyte supplementation has been evaluated extensively with growing and finishing cattle, but little to no work has been reported with cull cows. The objective of the two studies was to determine the effects of pre and post-transport electrolyte supplementation on weight loss, hydration, and meat quality in cull dairy cows. In the first study, sixty cull dairy cows (644.3 plus or minus 121.9 kg) were stratified by body weight, days of lactation, and farm of origin into two treatment groups (n=30). At 0500 cows were drenched with a solution of 2.4 g of dry electrolyte per kg of initial body weight, and diluted in approximately 1.5 L of water. Dry electrolyte was comprised of dextrose, sodium bicarbonate, magnesium sulfate and potassium chloride. Control group was given a placebo volume (1.5 L) of water. At 1700 cows were transported 3 h to a non-fed beef processor, unloaded and allowed 8 h of lairage time with access to water prior to slaughter. Body weight and blood were collected from cows prior to treatment and slaughter. Treated cows tended to remain more hydrated than control cows from dosage till slaughter as per a greater decrease in packed cell volume (PCV; P = 0.06). Also, LM samples from treated cows exhibited greater drip loss (P < 0.05) and tended to have a lower pH (P = 0.06) than samples from control cows. In the second study, forty-eight cull dairy cows (712.8 plus or minus 120.4 kg) were stratified by weight and days of lactation into three treatments (n=16). Cows were drenched with electrolyte treatment prior to transport or following transport using the same procedures as the first study. Weights and blood samples were taken prior to and after transport, and prior to slaughter, and meat quality evaluations were taken at 24 hr postmortem. No significant treatment effect on weight loss and hydration, indicated by PCV, was observed. However, cows treated after transport had a significantly lower plasma protein concentration change (P < 0.01) after lairage and during the duration of transport and lairage. There were strong numerical indicators that results are consistent with that of the first study in regards to packed cell volume, as well as more improved weight loses after transport and lairage. Our results showed, however, that cows started and remained more hydrated over the duration of the trial compared to cows from trial 1, indicated by lower PCV and PP values; likely attributed to less environmental and handling stress during the live animal portion of the study. These results show potential for electrolyte supplementation in cull cows to mitigate transport and handling stress to improve animal hydration and meat quality.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Travis Arp.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Carr, Charles Chad.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041905:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041905/00001

Material Information

Title: Effects of Preharvest Electrolyte Supplementation on the Hydration and Meat Quality of Cull Dairy Cows
Physical Description: 1 online resource (75 p.)
Language: english
Creator: Arp, Travis
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: electrolyte, hydration, meat, stress
Animal Sciences -- Dissertations, Academic -- UF
Genre: Animal Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Transportation and handling of cattle prior to slaughter are stressors which can impact weight change and postmortem muscle quality. Electrolyte supplementation has been evaluated extensively with growing and finishing cattle, but little to no work has been reported with cull cows. The objective of the two studies was to determine the effects of pre and post-transport electrolyte supplementation on weight loss, hydration, and meat quality in cull dairy cows. In the first study, sixty cull dairy cows (644.3 plus or minus 121.9 kg) were stratified by body weight, days of lactation, and farm of origin into two treatment groups (n=30). At 0500 cows were drenched with a solution of 2.4 g of dry electrolyte per kg of initial body weight, and diluted in approximately 1.5 L of water. Dry electrolyte was comprised of dextrose, sodium bicarbonate, magnesium sulfate and potassium chloride. Control group was given a placebo volume (1.5 L) of water. At 1700 cows were transported 3 h to a non-fed beef processor, unloaded and allowed 8 h of lairage time with access to water prior to slaughter. Body weight and blood were collected from cows prior to treatment and slaughter. Treated cows tended to remain more hydrated than control cows from dosage till slaughter as per a greater decrease in packed cell volume (PCV; P = 0.06). Also, LM samples from treated cows exhibited greater drip loss (P < 0.05) and tended to have a lower pH (P = 0.06) than samples from control cows. In the second study, forty-eight cull dairy cows (712.8 plus or minus 120.4 kg) were stratified by weight and days of lactation into three treatments (n=16). Cows were drenched with electrolyte treatment prior to transport or following transport using the same procedures as the first study. Weights and blood samples were taken prior to and after transport, and prior to slaughter, and meat quality evaluations were taken at 24 hr postmortem. No significant treatment effect on weight loss and hydration, indicated by PCV, was observed. However, cows treated after transport had a significantly lower plasma protein concentration change (P < 0.01) after lairage and during the duration of transport and lairage. There were strong numerical indicators that results are consistent with that of the first study in regards to packed cell volume, as well as more improved weight loses after transport and lairage. Our results showed, however, that cows started and remained more hydrated over the duration of the trial compared to cows from trial 1, indicated by lower PCV and PP values; likely attributed to less environmental and handling stress during the live animal portion of the study. These results show potential for electrolyte supplementation in cull cows to mitigate transport and handling stress to improve animal hydration and meat quality.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Travis Arp.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Carr, Charles Chad.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041905:00001


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EFFECTS OF PREHARVEST ELECTROLYTE SUPPLEMENTATION ON THE
HYDRATION AND MEAT QUALITY OF CULL DAIRY COWS
















By

TRAVIS STEVEN ARP


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2010

































2010 Travis Steven Arp
































To my parents for their endless support and guidance throughout my education









ACKNOWLEDGMENTS

I would like to thank Dr. Chad Carr first and foremost for his guidance and advice

throughout the duration of my graduate degree at the University of Florida. Not only has

Chad acted as an outstanding advisor and mentor while working on my masters degree,

but has also been a tremendous friend since my time as an undergraduate at the

University of Missouri. He made my transition from the Midwest to Florida much more

comfortable and he and his wife Cathy have become two of my closest friends in the

process. I have learned so much from Chad during my graduate work and will continue

to call upon him as a mentor and friend as I continue through graduate school and my

future career, regardless of where it takes me.

I would also like to thank Dr. Dwain Johnson and Dr. Todd Thrift from my graduate

committee, as well as Mr. Larry Eubanks from the meat science department. Each has

provided me with outstanding input to my research and each have a great

understanding of the beef industry. That insight has given me a much better

perspective in my research and a better understanding of the meat and beef industry,

particularly how it associates with the industries in Florida and the Southeast. The

knowledge I have gained from my entire committee has given me a more well-rounded

understanding of the regional differences among beef production systems in the United

States.

Special thanks go to all the graduate and undergraduate students who helped me

carry out both of my research projects; particularly Trey Warnock and Drew Cotton for

their help during the August study. Those were three of the hardest, hottest, and most

miserable days of the summer, and we would not have been able to complete our first

trial without their help. Also, thank you to John Michael Gonzalez, Kalyn Bischoff, Will









Sapp, Richelle Miller, Crystal Hale and Melissa Miller for their help during the December

study. Their help made the second trial run much more smoothly and reduced the

stress levels for everybody involved.

I am deeply indebted to Trey Warnock, Brett Wheeler, Drew Cotton, John Michael

Gonzalez, Tera Loyd, and Kalyn Bischoff for their friendship over the past two years,

along with the many other friendships I have developed while at UF. They have offered

a great amount of support and relief during our graduate programs and have made the

stress of class and research much more enjoyable.

Finally, I would like to give the biggest thanks to my family. My parents have

always been tremendously encouraging for me to follow my aspirations regardless of

where they take me. It has been their constant guidance and encouragement that has

motivated me to pursue a master's degree. They have always stood behind my

decisions and have let me shape my own future while pushing me to be the best at

everything I did and helping me in whatever way possible. I am truly blessed to have

such an understanding and supportive family that has allowed me to follow my goals,

even though they have taken me to the opposite side of the country. I owe any amount

of success to my mother and father, and appreciate the support of my brother and

sister, grandparents, and the rest of my family and friends over the years.









TABLE OF CONTENTS


page

ACKNOWLEDGMENTS......................... .....................4

L IS T O F T A B LE S ....................................... .......................... 8

L IS T O F F IG U R E S .......................................................... .. ............................ 9

A B S T R A C T ................. ................................................................................................. 1 0

CHAPTER

1 INTRO DUCTIO N ...................................................... .................. 12

2 R EV IEW O F LITERAT U R E ............................................................................... 15

Introduction................................... .............. 15
A n im a l W e lfa re ................................................... 16
Issues and R regulations ...................................................................... ........ 16
A n im a l H a n d lin g ..................................................................... 1 9
Stress Physiology ....................................................................... 21
Physiological Indicators of Stress ......... .... .............. .... ........ 21
Meat Quality Stress Indicators......................... .................... 24
Livestock Marketing and Stress Attenuation ........................ ............... 27
Stress During the Pre-Slaughter Period ................................. 27
Attenuation of Transport and Handling Stress ........... ......... ..... ............. 29

3 EFFECT OF ON FARM ELECTROLYTE SUPPLEMENTATION ON WEIGHT
LOSS, HYDRATION, STRESS, AND MUSCLE QUALITY.................. 36

M materials and M ethods ...................... ............................... ............................ 36
Animals and Management.............................................. 36
Experiment and data sampling on farm ....................... ....... ........... 36
Transport, harvest, antemortem and postmortem data sampling .............. 38
Blood Plasma Analysis ................................................. 39
Warner-Bratzler Shear Force .......................... ......... .......... 39
S statistical A na lysis ...................... ........................... .... ............................ 40
Results and Discussion ................................................. 40
Weight Loss and Hydration ...... ........... ..................... .... ......... 40
Plasma Protein Concentration ........................ .............. ......... 42
Carcass Traits ........................................ ....... ................... ... 42
W arner-Bratzler Shear Force .......................... ..................... ........ ....... 44
Im plic atio ns ...... .. .. ....... .. .. ...... .................................. ............. 44









4 EFFECT OF ON-FARM AND POST-TRANSPORT ELECTROLYTE
SUPPLEMENTATION ON WEIGHT LOSS, HYDRATION, STRESS, AND
MUSCLE QUALITY .......... ......... ... ......... ............... .... ............ 48

Materials and Methods ........ .......... ......... ............... ....... ........ 48
Animals and Management............... ... .......... ............. 48
Experiment and data sampling on farm.............. ...... .................. 48
Transport and plant electrolyte treatment..... ......... .... ................ 50
Lairage, harvest, and postmortem sampling ................ .......... ......... 50
Blood Analysis ......................... ......... ........... 52
W arner-Bratzler Shear Force ............................... ..................... 52
Statistical Analysis ............... ..... ........ ................. 52
Results and Discussion ........... ................ ............... ......... ............... 53
W eight Loss and Hydration ........................................................................ 53
Plasma Protein and Cortisol Concentration.............. ...... .................. 55
M e a t Q u a lity ......... ............... ........... ............... .......... .... ...... 5 6
Warner-Bratzler Shear Force and Cooking Loss .................. .......... ......... 57
Im p licatio ns ......... ............. ..... .... ....... .............. ................ .... 57

LIST OF REFERENCES ......................... ........ ........... 66

BIO G RA PH ICA L S KETC H ......................................................................... ......... 75









LIST OF TABLES


Table page

2-1 Physiological assessment of stress in transported cattle ........ ............... 33

2-2 Normal muscle quality characteristics of advanced maturity beef .............. 34

3-1 Ingredients of electrolyte supplement ............................... .................... 45

3-2 Effect of on-farm electrolyte supplementation on pre-slaughter body weight
loss ....... ...... ......... ................................... ........ 45

3-3 Effect of on-farm electrolyte supplementation on packed cell volume of whole
blood during pre-slaughter period............. ........... ..... ......... .............. 46

3-4 Effect of on-farm electrolyte supplementation on blood plasma protein
co nce ntratio n ................................................ ................. 46

3-5 Carcass characteristics by treatment group ................. ............................ 46

3-6 Effect of on-farm electrolyte supplementation on LM and SM pH and
objective color measurements and LM drip loss............. ............ 47

3-7 Effect of on-farm electrolyte supplementation on Warner-Bratzler shear force
and cooking loss ............ .................. ........................................... 47

4-1 Ingredients of electrolyte supplement .................. .. ......... .......... 58

4-2 Effect of pre and post-transport electrolyte supplementation on weight loss
during transport and lairage........................... ... .................. ........... .... 59

4-3 Effect of pre and post-transport electrolyte supplementation on packed cell
volume (PCV) ............. ..... .... .......... ................................... 60

4-4 Effect of pre and post-transport electrolyte supplementation on plasma
protein (PP) concentration ... .. ..................................... .... .......... .. 61

4-5 Effect of pre and post-transport electrolyte supplementation on plasma
cortisol concentration .............................................................. ... ........... 62

4-6 Carcass characteristics by treatment group .............. .................................... 63

4-7 Effect of pre and post-transport electrolyte supplementation on pH and
objective color measurements of the LM and semimembranosus and LM drip
lo s s .............. ... ..... ...... .......... ....... ........... ......... ........ ...... 6 4

4-8 Effects of pre and post-transport electrolyte supplementation on Warner-
Bratzler shear force and cooking loss................. ................... 65









LIST OF FIGURES


Figure page

2-1 The relationship of postmortem pH decline with characteristics of beef
muscle, adapted from Aberle (2001) .......... ......... ........................... 35

2-2 The relationship of beef muscle pH to water holding capacity, adapted from
W ismer-Pedersen (1987) ... ... .............................................. .. ........... .... 35









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

EFFECTS OF PREHARVEST ELECTROLYTE SUPPLEMENTATION ON THE
HYDRATION AND MEAT QUALITY OF CULL DAIRY COWS
By

Travis Steven Arp

August 2010

Chair: Chad Carr
Major: Animal Sciences

Transportation and handling of cattle prior to slaughter are stressors which can

impact weight change and postmortem muscle quality. Electrolyte supplementation has

been evaluated extensively with growing and finishing cattle, but little to no work has

been reported with cull cows. The objective of the two studies was to determine the

effects of pre and post-transport electrolyte supplementation on weight loss, hydration,

and meat quality in cull dairy cows. In the first study, sixty cull dairy cows (644.3

121.9 kg) were stratified by body weight, days of lactation, and farm of origin into two

treatment groups (n=30). At 0500 cows were drenched with a solution of 2.4 g of dry

electrolyte per kg of initial body weight, and diluted in approximately 1.5 L of water. Dry

electrolyte was comprised of dextrose, sodium bicarbonate, magnesium sulfate and

potassium chloride. Control group was given a placebo volume (1.5 L) of water. At

1700 cows were transported 3 h to a non-fed beef processor, unloaded and allowed 8 h

of lairage time with access to water prior to slaughter. Body weight and blood were

collected from cows prior to treatment and slaughter. Treated cows tended to remain

more hydrated than control cows from dosage till slaughter as per a greater decrease in

packed cell volume (PCV; P = 0.06). Also, LM samples from treated cows exhibited









greater drip loss (P < 0.05) and tended to have a lower pH (P = 0.06) than samples from

control cows.

In the second study, forty-eight cull dairy cows (712.8 120.4 kg) were stratified

by weight and days of lactation into three treatments (n=16). Cows were drenched with

electrolyte treatment prior to transport or following transport using the same procedures

as the first study. Weights and blood samples were taken prior to and after transport,

and prior to slaughter, and meat quality evaluations were taken at 24 hr postmortem.

No significant treatment effect on weight loss and hydration, indicated by PCV, was

observed. However, cows treated after transport had a significantly lower plasma

protein concentration change (P < 0.01) after lairage and during the duration of

transport and lairage. There were strong numerical indicators that results are consistent

with that of the first study in regards to packed cell volume, as well as more improved

weight loses after transport and lairage. Our results showed, however, that cows

started and remained more hydrated over the duration of the trial compared to cows

from trial 1, indicated by lower PCV and PP values; likely attributed to less

environmental and handling stress during the live animal portion of the study.

These results show potential for electrolyte supplementation in cull cows to

mitigate transport and handling stress to improve animal hydration and meat quality.









CHAPTER 1
INTRODUCTION


Cull cows and bulls play a very important role in today's beef industry. The non-

fed beef industry accounts for approximately 15% of today's domestic beef production

(NCBA, 1999). Of that percentage, about one-third is comprised of the harvest of cull

dairy cows (NCBA, 1999). Dairy cows are culled from the herd for various reasons,

including: reproductive inefficiency, low milk yield, mastitis, and lameness (Hadley et al.,

2006). Many cull cows are marketed through an auction market prior to being

harvested at non-fed beef processing facilities. A large portion of Florida cull cows are

sold directly to the processor due to their close proximity and the economy of scale

associated with Florida's large ranches and dairy operations.

The marketing of cattle can require long transport times and excessive handling.

According to the 2007 National Market Cow and Bull Beef Quality Audit, loads of non-

fed cattle traveled an average of 5.9 h to beef processing facilities, with maximum

transport times of up to 32 h (NCBA, 2007). Livestock often go without water or feed

during transportation, and are limited to only water when held in lairage prior to

slaughter. Transportation, exposure to a new environment and novel animals, and

weather extremes, all can and will induce a stress response from the animal (Grandin,

1997). The stress response is characterized by the release of the catecholamines,

epinephrine and norepinephrine, from the adrenal medulla which increases heart rate

and blood pressure (Knowles and Warris, 2000). The catecholamines also induce a

signaling cascade along the hypothalamic-pituitary-adrenal axis that releases various

hormones that effect the mobilization of body tissues and depletion of energy stores

during times of stress through lipolysis, glycogenolysis, and protein catabolism (Selye,









1939). This leads to a negative energy balance, dehydration and weight loss during

transport, along with decreases in dressing percentage and carcass yield. The

autonomic stress response and its relationship with elevated postmortem pH and dark

cutting beef has been well documented (Knowles et al., 1999).

Multiple studies have been done to attenuate the effects of transport stress in

finished cattle through the use of electrolyte supplementation and pre-slaughter

conditioning regimens. Providing livestock with an energy, ion, or amino acid

supplement following stressful periods can aid in the recovery of muscle glycogen

depletion, which can prevent dry, firm, and dark meat quality issues (Cole and

Hutcheson, 1985; Schaefer et al., 1997; Schaefer et al., 2001). Furthermore,

reestablishing the sodium and potassium ion balance within the body will aid in the re-

absorption of intracellular water (Tasker, 1980) and result in improved hydration,

decreased weight loss and improved carcass yield during transport and harvest

(Schaefer et al., 1997).

A lactating dairy cow is fed a high energy diet during production; withholding a cow

from feed prior to transportation and slaughter will result in an energy deficit. The

combination of a dietary energy deficit, the stress of a full udder, and all other pre-

slaughter stressors makes a cull dairy cow an ideal subject for research to improve non-

fed beef quality through stress attenuation.

The objectives of the current study were to assess the impact of dietary electrolyte

supplementation on weight loss, stress, hydration, and meat quality of cull dairy cows

when supplemented prior to and immediately following transportation to harvesting

facilities. It is hypothesized that electrolyte treatment will allow cows to remain more









hydrated, lose less weight during marketing, and improve muscle pH and objective color

measurements.









CHAPTER 2
REVIEW OF LITERATURE

Introduction

The 1999 National Market Cow and Bull Beef Quality Audit (NFBQA) stated that

approximately 29% to 33% of the nation's dairy herd and 9% to 11% of the beef herd is

culled annually; ultimately accounting for approximately 15% of the total United States

beef production (NCBA, 1999). Nearly 75% of non-fed beef in the U.S. is generated by

culls cows; half of which is from slaughtered dairy cows, thus accounting for over 5% of

all U.S. beef production (NCBA, 1999). Much of the product derived from the slaughter

of non-fed cattle is used for the production of ground beef, which accounts for nearly

45% of the beef consumed in the U.S. (NCBA, 1999). However, the audit also showed

that non-fed beef packers will market up to 75% of cow or bull carcasses as whole

muscle cuts for roast beef, deli meats, or steaks and roasts at low price food service

facilities (NCBA, 1999). Due to the impact the cull cow industry has on beef production,

ensuring the welfare of cull cows is important for cattle producers and packers.

Dairy cattle in production are culled for a variety of reasons; old age, reproductive

inefficiency, and lameness. Specifically, Hadley et al. (2006) reported that injury,

reproduction, production, and mastitis issues represent the most prevalent reasons for

dairy cows leaving the herd. These and the other multiple culling factors potentially

relate to issues that result in condemnation of the viscera, head, hide, or whole carcass.

However, less than 1% of non-fed cattle are condemned during antemortem and

postmortem inspection, respectively (NCBA, 2007).

Much of the variation in carcass merit and end product quality is caused by the

challenges incurred during marketing and transport to slaughter. From the time an









animal leaves the farm until it is slaughtered, there are a multitude of stressors which

are encountered. Animals can encounter psychological stress from restraint, transport,

handling, and novelty, or physical stress from hunger, thirst, fatigue, injury or thermal

extremes (Grandin 1997). All of these can affect antemortem and early postmortem

muscle metabolism, ultimately impacting meat quality (Huff-Lonergan and Lonergan,

2005). Feed and water restriction during the pre-slaughter period can cause severe

weight loss and decreases in dressing percent (Jones et al., 1988).

The increasing importance of the consumer's perception of animal agriculture

and the economic significance of the previously mentioned traits have led to the need

for more research evaluating livestock during the pre-slaughter period. The use of

electrolyte supplementation and pre-slaughter conditioning treatments have shown to

improve several measures of stress, hydration, and muscle quality in fed steers and

heifers (Schaefer, 2001; Schaefer et al., 2006). However, few studies have been

conducted utilizing cull cows.

Animal Welfare

Issues and Regulations

Animal agriculture faces continued pressure from animal activist groups and

speculation from the public on the practices involved in the packing industry. The

majority of livestock producers provide excellent husbandry. However, the isolated

incidents of poor stewardship that are broadcast nationally resonate amongst the public

and increase the scrutiny on all of animal agriculture.

All packers are required to adhere to the Humane Slaughter Act (USDA-FSIS,

2009a), and almost all utilize humane handling guidelines set forth by the American

Meat Institute (AMI, 2005). Of particular importance is that cattle are rendered









insensible to pain prior to exsanguination after a proper stunning procedure has been

completed. Prior to and proceeding slaughter, all livestock and carcasses are inspected

for potential health problems that could affect food safety (USDA-FSIS, 2009b).

Livestock are observed both at rest and in motion before entering the plant, and a

thorough inspection of the head, viscera, and carcass is conducted after exsanguination

(USDA-FSIS, 2009b). The Recommended Animal Handling Guidelines and Audit Guide

(AMI, 2005) outlines procedures for producers and packers to minimize welfare risk

during handling and transportation of livestock. These include: facility assembly and

setup, proper loading, unloading, and movement, and humane stunning and

postmortem handling (AMI, 2005). All antemortem and postmortem measures are

taken to ensure animal welfare and food safety.

Broom (1991) defines welfare as "the state of an individual in relation to its

environment." Multiple studies have shown that the welfare associated with sound

stockmanship practices allow animals to produce at optimal levels (Grandin, 2003).

Therefore, livestock producers and packers have an imbedded interest in utilizing good

stockmanship practices. Transportation, comingling, handling, and lairage prior to

slaughter are all stressors which can impact animal health and meat quality (Grandin,

1997).

The issue of non-ambulatory or "downer" cows is one of particular interest in the

cull cow industry. The United States Department of Agriculture Food Safety and

Inspection Service (USDA-FSIS, 2004) defines non-ambulatory as:

Animals that cannot rise from a recumbent position or that cannot walk,
including but not limited to those with broken appendages, severed tendons
or ligaments, nerve paralysis, a fractured vertebral column, or metabolic
conditions.









State and federal legislation has been enacted over the past two decades to prohibit the

buying, selling, and receiving of downer cattle in the United States, spurred by media

footage of mistreated downer cows in California in 1993 (Stull et al., 2007). However, a

federal ban on the slaughtering of all downer cows in the U.S. was not enacted until

after the first confirmed case of Bovine Spongiform Encephalopathy (BSE) in the United

States on December 23, 2003 (Stull et al., 2007). These policies have been met with

both praise and criticism from producers and packers as it improves the safety of our

food supply, but has a negative economic impact on producers by eliminating downer

cows that are simply injured and still acceptable for human consumption.

A common criticism of the beef industry has been the treatment of downer cattle

at slaughter facilities. The American Veterinary Medical Association has established

best management practices for handling downer cows (Stull et al., 2007). However,

there has continued to be cases of mistreated down-cows (Stull et al., 2007). These

instances are often highly publicized by national media and continue to cause

skepticism of the practices of producers and packers, as well as the safety of the U.S.

food supply. The most significant event occurred in February, 2008, when the non-fed

beef packer, Hallmark/Westland Meat Packing Co. in Chino, CA was required to recall

over 143 million pounds of beef products due to inhumane handling of non-ambulatory

cows (USDA-FSIS, 2008). This became a policy changing event in the U.S. meats

industry, and resulted in the largest ever recall by FSIS, as well as the only ever recall

for a non-food safety concern. Additionally, this event led to the increased attention on

humane handling and slaughter set forth by FSIS in 2008 (USDA-FSIS, 2009a). It is

crucial that all segments of the beef supply chain place the utmost importance on









animal welfare due to the overwhelming media coverage of these cases and negative

ramifications it has on the meat industry.

Animal Handling

Animal handling has a large impact on livestock stress. There are multiple

opportunities for animals to be exposed to stress during the process of transportation

from the farm to their ultimate destination. Humans should handle livestock to limit

anxiety responses that can cause negative physiological outcomes.

Handling responses can be most notably recognized through behavioral

reactions (Broom, 2000). Cattle exposed to a new object such as a trailer or handling

facility will balk and/or give vocalized responses to the strange object (Grandin, 1997).

However, as familiarity increases, livestock will become more cooperative with entering

a new area (Peischel et al., 1980; as cited in Grandin, 1997). Stress responses can be

objectively measured by evaluating metabolic rate, such as heart rate, blood pressure,

respiration rate, and body temperature; plasma cortisol (Table 2-1); and adrenal

medullary hormones, such as epinephrine and norepinephrine (Broom, 2000).

Handling effects are compounded when animals are exposed to human handling

techniques that elicit pain. Abusive practices by humans will be recollected by animals

and can cause similar and exaggerated behavioral and physiological responses to

general handling stressors (Grandin, 1997). Animals recollect negative experiences,

and research has shown that calves have recognition of people they have had positive

or negative interactions with (de Passille et al., 1996; as cited by Gonyou, 2000).

The use of paddles, prods, whips, and hot shots are commonly found in livestock

production facilities (NCBA, 2007) and are often times necessary to provoke efficient

movement of livestock. However, it is the manner in which these tools are used that









dictates the animal reaction. In the 2007 Non-fed Beef Quality Audit (NCBA, 2007),

22.3% of all loads of cattle received applied the use of a hot shot to aid movement at

the packing plant. Most plants (86.4%) reported using driving aids other than hot shots

in a passive manner, however, 13.6% of plants reported using driving aids, including

sticks, paddles, body parts, PVC pipe, metal pipe, whips, and a flash light; in an

aggressive manner (NCBA, 2007). The aggressive use of driving devices will evoke a

stress response and can compromise animal welfare. Thus, it is of utmost importance

that animal handlers minimize aggressive handling to preserve animal welfare.

An animal which incurs a slip or fall during the process of loading or unloading

will become stressed and exacerbate responses for the remainder of the lot. Care

should be taken to ensure secure footing for livestock, especially when encountering a

ramp, landing, or turning area (Tarrant and Grandin, 2000).

Transport stocking density and the surface of the trailer floor play a major role in

animal balance and the number of times an animal slips or falls because cattle tend to

stand during transport (Tarrant and Grandin, 2000). It is recommended that mature

cows are allowed approximately 0.25 to .030 m2 per 100 kg of body weight during

transport (AMI, 2005). Tarrant et al. (1992) reported low stocking density had fewer

animal struggles and falls than high stocking densities. However, it was also shown that

there were less load shifts when stocking density was high (Tarrant et al., 1992; as cited

by Tarrant and Grandin, 2000). A high transport stocking density will tend to restrict

animal movement in the trailer, but cattle which do fall will be at greater risk for injury

and subsequent bruising, with little room to return to a standing position. Livestock tend









to be more comfortable at lower stocking densities; but their balance is affected by

driving techniques (Tarrant and Grandin, 2000).

Stress Physiology

Physiological Indicators of Stress

The innate interactions of animal biology make stress levels challenging to

quantify in-vivo. The initial response to stress is indicated by the release of the

catecholamines, epinephrine or adrenaline, released from the adrenal glands, and

norepinephrine or noradrenaline, released from both the adrenal glands and

sympathetic nerve endings (Knowles and Warris, 2000). In turn, both hormones

increase heart rate, blood pressure and the rate of glycogenolysis, thus raising plasma

glucose levels shortly after the initial stress reaction (Knowles and Warris, 2000). Yet,

due to the relatively short half lives of these hormones, they are a useful, albeit

inconsistent measure of animal stress (Knowles and Warris, 2000).

The hypothalamic-pituitary-adrenal (HPA) axis is a complex system of integrated

hormonal and neural networks that work to control an animal's response to stress

(Selye, 1939). Catecholamine release stimulates the release of corticotrophic releasing

factor (CRF) from the hypothalamus of the brain (Plotsky et al, 1989),

adrenocoricotrophic hormone (ACTH) from the anterior pituitary of the brain (Dinan,

1996), and glucocorticoids from the adrenal cortex (Dinan, 1996).

Of the glucocorticoids released, cortisol is of primary interest in mammalian

species. Through increases in cortisol levels, it enhances the function of

gluconeogenesis, increases proteolysis, and alters CRF and ACTH release through

negative feedback (Dickson, 1970). Considering this response is heavily mediated

through the brain and has a longer half-life than epinephrine and norepinephrine,









measuring blood cortisol levels is a useful way of determining an animal's reaction to

prolonged stress (Knowles and Warris, 2000; Table 2-1).

The release and absorption of water is controlled by release of antidiuretic

hormone (ADH) from the posterior pituitary (Houpt, 1970). During dehydration, a

change in the osmoconcentration of plasma stimulates ADH release causing urine

volume to decrease in an effort to retain water (EI-Nouty et al., 1980). The fluid lost

during dehydration is mostly from the extracellular fluid (Houpt, 1970). There is a shift

from water in the cells to the extracellular fluid, which is then lost through urine, feces,

respiratory gasses, and perspiration (Houpt, 1970). Electrolytes are also lost from the

extracellular fluid during water deprivation. Sodium (Na+), potassium (K+), chloride (CI-),

and bicarbonate (HCO3) levels in the plasma, blood, and urine often increase during

periods of dehydration (Houpt, 1970). Aldosterone is the primary hormone responsible

for reabsorption of Na and K and is regulated by ACTH from the anterior pituitary

(Houpt, 1970). Dehydrated animals tend to have lower levels of plasma aldosterone

associated with increased urine sodium levels (EI-Nouty et al., 1980).

Packed cell volume (PCV) is a measure of the percentage of cells occupying the

total blood volume, and is measured by evaluating the proportion of plasma to cellular

constituents in a blood sample (Knowles and Warris, 2000). PCV is a simple

measurement of dehydration and is often accompanied with measurements of plasma

protein and plasma albumin levels to confirm the degree of dehydration (Knowles and

Warris, 2000) (Table 2-1).

An increase in PCV percentage is indicative of either decreased plasma volume

or increased cellular components in the blood, and would thus indicate a more









dehydrated state (Kent and Ewbank, 1983). There are multiple proteins which comprise

total protein found in the plasma. These proteins include: albumins, globulins,

fibrinogens, along with multiple other regulatory proteins (Smith and Hamlin, 1970).

Plasma proteins serve primarily as transport proteins, as well as regulating osmotic

pressure, clotting factors, and aid in immune response (Smith and Hamlin, 1970).

During periods of dehydration, acute stress, or energy deficiency, plasma protein

concentrations tend to increase due to mobilization of proteins to utilize as an energy

substrate, or a decrease in total plasma volume (Siebert and Macfarlane, 1975) (Table

2-1). The loss of blood, urine, and muscle metabolites also are an indication of

dehydration as sodium, potassium, chloride, and bicarbonate are all depleted during

fasting or while being withheld from water (Schaefer et al., 1989). This can be most

easily understood through calculation of the anionn gap" value [serum (Na+ + K+) -

(HCO-3 + Cl-)] (Schaefer et al., 1990). Lower values are an indicator of more normal

hydration levels (Schaefer et al., 1990).

During normal muscle activity, glycogen is the main carbohydrate store for

muscle energy. Glycogen is broken down by glycolysis into two glucose molecules that

can be utilized as energy in aerobic metabolism (Aberle et al., 2001). The glucose is

broken down into two pyruvic acid molecules which then enter the tricarboxylic acid

cycle to produce a net 37 ATP for energy (Aberle et al., 2001). During anaerobic

conditions, the byproduct of glycolysis is lactic acid. Lactic acid is then transported to

the liver and rephosphorylated through the Cori cycle to glucose molecules through

gluconeogenesis (Martin and Vagelos, 1962). As the intensity of muscle activity builds,

there is a tendency to shift to a greater anaerobic metabolism, thus the catabolism of









glycogen causes a build-up of lactate as a byproduct of anaerobic activity in the muscle

and blood stream (Knowles and Warris, 2000). Along with this, creatine phosphokinase

(CPK) is utilized by muscle to make ATP available for contraction. During strenuous

muscle activity, creatine kinase (CK) in the form of CK3 leaks from muscle cells and can

be detected in the blood analysis (Knowles and Warris, 2000). As such, both lactate

and CK are also commonly measured parameters to indicate muscle stress.

Adipose tissue is catabolized through lipolysis. The pancreatic hormone glucagon

stimulates adipose mobilization during periods of low blood glucose (Allen, 1970).

Adipose tissue is broken down to triglycerides, which are further catabolized into acetyl-

CoA through beta-oxidation (Allen, 1970). An acetyl-CoA molecule then undergoes

oxidative phosphorylation to produce ATP for energy utilization (Allen, 1970). The

mobilization of adipose tissue for energy can be detected in the form of free fatty acids

(FFA) and ketone bodies in the blood. When triglycerides are mobilized, they are

broken down into the glycerol and non-esterified free fatty acid (NEFA) or FFA

components (Knowles and Warris, 2000). The liver converts the FFA to ketone bodies

in the liver, particularly beta-hydroxybutyrate (3-OHB), which is utilized by the tissues

(Knowles and Warris, 2000).

Meat Quality Stress Indicators

Stress events can affect live animal physiology, which can cause meat quality

aberrations. The live animal uses glycogen as a carbohydrate source of energy for

muscle contraction and lactic acid is produced as a byproduct of glycogenolysis

(Jensen, 1954). When an animal is exanguinated, the absence of oxygen in the blood

causes a shift from aerobic to anaerobic metabolism (Aberle et al., 2001). Since the

circulatory system can no longer carry lactate to the liver to be re-synthesized into









glucose and glycogen, lactic acid begins to concentrate within the muscle and cause the

postmortem pH decline (Aberle et al., 2001). The rate of acidification is primarily

determined by the rate of muscle metabolism immediately before, during, and after

slaughter (Aberle et al., 2001; Figure 2-1). An animal which is exposed to prolonged

chronic stress, will have in-vivo glycogen depletion resulting in insufficient lactic acid

production, and ultimately elevated pH values (> 5.8; Hedrick et al., 1959). This beef

will have increased water holding capacity, and a dark lean color due to increased light

absorbency (Hedrick et al., 1959; Figure 2-2). Extreme cases of glycogen depletion

cause a dry, firm and dark (DFD) condition or a "dark cutter" (Figure 2-1). The

increased pH holds myoglobin, the primary protein responsible for muscle color, in the

ferrous state which also causes a darker lean color (Lawrie, 1958). The surface of DFD

meat appears very dry due to increased water holding capacity, caused by a pH higher

than normal beef that is further from the isoelectric point, resulting in a more open

protein lattice with more ability to bind water (Lister, 1988).

When animals are exposed to acute stress immediately prior to harvest, glycogen

is metabolized quickly while muscle temperature is high, causing rapid accumulation of

lactate and its associated decline of muscle pH (Briskey, 1964). This rapid acidification

of muscle during early post-mortem metabolism denatures the protein and results in

pale, soft, and exudative (PSE) meat (Figure 2-1). This is a significant quality defect in

species with faster metabolizing, more glycolytic muscle proteins than beef. Thus, PSE

is primarily a problem within the pork industry (Scanga et al., 2003), but also in turkeys

(Barbut, 1993) and chickens (Barbut, 1997). In contrast to normal or DFD meat, PSE

meat has less ability to bind water (Figure 2-2), causing greater surface moisture, and









denatured myofibrils resulting in greater surface light reflectance and a soft texture

(Briskey, 1964)

Other factors contributing to the rate of pH decline include: in vivo temperature,

chilling rate, and conditions at the onset of rigor mortis (Aberle et al., 2001).

Considering the conversion of muscle to meat has a sizeable impact on water holding

capacity, color, texture, and shelf life, determining muscle pH is of primary importance

for quantifying fresh meat quality.

Color can be quantified objectively using a Hunter or Minolta colorimeter. The

majority of domestic research uses a colorimeter to evaluate black to white (lightness;

L* value; range = 0 to 100), green to red (redness; a* value; range = -60 to 60), and

blue to yellow yellownesss, b* value; range = -60 to 60; Hunter, 2006). Objective

colorimetry is used extensively within the meat industry due to its association with other

meat quality attributes and consumer retail acceptability (Kropf, 1980). L*, a*, and b*

scores are highly correlated to muscle pH and physiological maturity in beef cattle

(Page et al., 2001). Additionally, it is well established that color is the primary driver of

fresh retail meat purchasing (Faustman and Cassens, 1990) and consumers prefer

reflective, youthful, beef products (Jeremiah et al., 1972).

Ultimate pH has a dramatic impact on fresh meat shelf life. Beef with a higher

pH than normal has increased water holding capacity and thus allows for increased

microbial growth, odors, and surface discoloration (Hood and Tarrent, 1981).

Furthermore, DFD beef is associated with poor sensory attributes and is identified by

increased instances of off-flavors (Wulf et al., 2002). As such, dark cutting beef has

little appeal to the consumer. Naumann et al. (1957) determined that consumers









evaluate meat purchases based on visual appearance and palatability. When

purchasing fresh meat from the retail case, consumers must rely on their visual

appraisal to aid in purchasing decisions. Therefore, beef that exhibits the

aforementioned quality defects will be consistently passed over by the consumer.

Beef from cattle with an older chronological age will tend to have a darker color

than young beef, regardless of stress. Beef from older animals has a higher

concentration of myoglobin, which are the proteins responsible for muscle color (Aberle

et al., 2001). Beef from older cattle is also characterized as tougher, with higher

Warner-Bratzler shear force (WBSF), as there is a strengthening of connective

structures within the muscle (Aberle et al., 2001). There is little change in the

concentration of connective tissue within the muscle, however collagen and elastin

cross-links increase, which reduce the solubility of the fibers (Aberle et al., 2001). Berry

et al. (1974) reported steaks from carcasses B maturity and younger to have

significantly less connective tissue scores by a trained sensory panel than from C

maturity or older carcasses, as well as more desirable overall palatability. Breidenstein

et al. (1968) also reported that steaks from E maturity carcasses had higher shear force

values than those from A and B maturity carcasses. Values for meat quality properties

of beef from aged cattle are indicated in Table 2-2.

Livestock Marketing and Stress Attenuation

Stress During the Pre-Slaughter Period

Livestock are subject to numerous stressors. However, the pre-slaughter period,

including transportation and lairage, might be as stressful an experience as any in

production. The specific effects of transportation itself have been poorly defined;









however, the literature suggests that when transportation and lairage is combined with

fasting and elimination of water availability, it exacerbates stress effects (Jones, 1988).

During transportation animals can often be withdrawn from feed for hours at a

time. According to the 2007 NFBQA (NCBA, 2007), all loads of non-fed cattle traveled

an average of 5.9 h and 454.6 km. With tractor-trailer loads, these values increased to

8.6 h and 658.5 km respectively (NCBA, 2007). Typically these cattle are withheld from

water during transport, and withheld from feed after leaving the farm, unless spending

more than 24 h prior to being slaughtered at the packing facility.

Jones et al. (1988) reported that steers and heifers fasted 24 or 48 h and

transported 320 km tended to have greater live weight losses and lighter carcasses than

those fasted 24 h with no transport. Similar results have been found in a follow up by

Jones et al. (1990) reporting increased weight loss with an increase in fasting time.

These significant weight losses affect both producers and packers by reducing carcass

weight and red meat yield. Also, literature has shown that increased time off feed

causes increased cooler shrink (Jones et al., 1988; 1990). Additionally, less desirable

hide dryness scores and increased difficulty of separating the hide form subcutaneous

fat were observed by Jones et al. (1990). Both of these findings indicate that

dehydration was the leading culprit for weight losses.

Any stressor can increase metabolic rate, and since transported livestock have

been withdrawn from feed, a negative energy balance can occur. The negative energy

balance of the animal gives precedent for livestock to mobilize body tissues to utilize as

energy (Moe et al., 1971). This can be detected through the release of metabolites in

the blood and urine during and after times of prolonged stress exposure. Most notable









are increases in urine osmolarity, which suggest increases in blood metabolites

released in the urine and is an additional measure of dehydration (Schaefer et al.,

1990). Studies done by Ruppanner et al. (1978) have reported shifts in sodium,

potassium and other fluid levels as a competent indicator of stress in feedlot cattle, as

well as decreased saliva sodium concentrations (Post, 1965) and decreased potassium

within the perspiration of fasted, transported dairy cattle (Schaefer et al., 1990). In a

review by Knowles and Warris (2000), slaughter cattle have exhibited increases in FFA,

13-OHB, plasma protein, serum albumin, PCV, CK, and lactate, decreased glucose, and

altered blood urea nitrogen concentrations, compared with control cattle (Knowles and

Warris, 2000). Jones et al. (1988) reported carcasses from fasted and transported

animals had a higher proportion of bone to lean and fat compared to carcasses from

control animals. This would be attributed to a chronic stress response affecting protein

and adipose catabolism.

Meat quality also suffers when animals are exposed to prolonged stress. Studies

have shown that bulls subject to increased transport stress have higher postmortem pH

at 45 min, and 24 and 48 h postmortem (Schaefer et al., 1990). These bulls also

tended to have darker (lower L* value) and less red (lower a* values) lean color, and

less drip loss due to a higher postmortem pH (Schaefer et al., 1990). Schaefer et al.

(2006) suggested that by decreasing stress by using an intervention, it is possible to

decrease instances of dark cutting beef.

Attenuation of Transport and Handling Stress

Livestock will experience a stress response during the normal activities

associated with marketing. The magnitude of the effects of stress during marketing has

an impact on economically important traits, making it a valued research topic. There









have been numerous studies using various methods to mitigate transport and handling

stress in young calves and finishing cattle, but very little evaluating cull cows

(Hutcheson et al., 1984; Cole and Hutcheson, 1985; Schaefer et al., 1990; Gortel et al.,

1992; Schaefer et al., 1992). The two interventions most commonly researched have

been the use of electrolyte supplementation and pre-slaughter conditioning prior to

transport (Fike and Spire, 2006).

Electrolyte supplementation has the ability to replenish blood metabolites and

return acid-base balance in the body to more acceptable levels (Schaefer et al., 1997).

Typically, most electrolyte solutions are comprised of a carbohydrate source, such as

glucose, dextrose or sucrose; a bicarbonate derivative, such as sodium bicarbonate or

potassium bicarbonate; an agent to aid in water absorption, such as sodium chloride or

magnesium sulfate; as well as other additives to restore body metabolites and balance

ion and electrolyte charges. Research has shown that electrolyte supplementation is

successful at decreasing body weight loss during transport and improving hot carcass

weight and carcass yield (Schaefer et al., 1990; Gortel et al., 1992; Schaefer et al.,

2006). Gortel at al. (1992) observed that crossbred bulls given electrolyte during lairage

tended to exhibit better recovery from transport stress by having lower live weight

decreases during lairage and had heavier hot carcass weights and greater carcass

yields than non-supplemented bulls. Gortel et al. (1992) reported that the increase in

hot carcass weight and carcass yield was attributed to great intracellular fluid retention

by treated bulls. In the same study, bulls that were supplemented electrolyte tended to

lose more live weight than bulls supplemented with only water (Gortel et al., 1992).

However, electrolyte treated bulls had greater hot carcass weights and carcass yields









than water treated bulls (Gortel et al., 1992) Gortel et al. (1992) suggested that this

could be attributed to electrolyte treated bulls losing more "drop weight" consisting of fill,

blood, pluck, and hide, but retaining more carcass tissue than control bulls. Numerous

other studies have reported similar effects on carcass yield and weight loss in bulls,

steers, and heifers (Jacobson et al., 1993; Schaefer et al., 1993; Scott et al., 1993).

Electrolyte supplementation has been shown to have impact on meat quality

through the restoration of acid-base balance and replenishment of body metabolites.

Schaefer et al. (1990) found that bulls supplemented with electrolyte tended to have

lower serum Na, K, and Cl- concentrations, as well as significantly lower urine Na and

K concentrations and higher muscle Na levels than control bulls. These researchers

reported bulls supplemented with electrolyte had lower, more normal initial pH, a lighter,

more reflective color, and lower Warner-Bratzler shear force values than control bulls

(Schaefer et al., 1990). Electrolyte therapy of transported cattle also showed to

decrease the instances of dark cutters compared to cattle offered only water (Schaefer

et al., 1997).

The use of altering the feed regimen of livestock prior to transport has also been

used to mitigate stress response. This intervention is used as supplemental energy pre-

transport to increase blood glucose to prevent mobilization of adipose and protein tissue

during the pre-slaughter period. Cole and Hutcheson (1985) reported that calves

offered a concentrate diet ad libitum prior to fasting lost more weight during deprivation,

but regained weight quicker after 3 days of refeeding than those given a restricted feed

regimen. It also showed that increased pre-fasting feed intake offers a larger reserve of

energy, water, and electrolytes in the body during deprivation, and thus allows the









animal to return to a their optimal level of intake more quickly after transport (Cole and

Hutcheson, 1985). Research also shows that cattle fed a high energy pre-slaughter

conditioning supplement tend to have a greater carcass yield, fewer instances of dark-

cutting beef, a greater proportion of USDA Prime and Choice carcasses, and fewer

USDA Select and No-Roll carcasses (Schaefer et al., 1999; 2006). Also, considering

the relationship of dark-cutting beef with increased stress, the use of pre-slaughter

conditioning or electrolyte utilization can markedly improve indicators of stress and

welfare (Schaefer et al., 2006).

Specific diet constituents can also be identified to improve certain other

responses. Supplementation of specific amino acids can improve meat quality as

physiological regulators of stress, substrates for amino acid metabolism, or substrates

for gluconeogenesis (Schaefer et al., 2001). Tyrosine is a precursor for epinephrine,

norepinephrine, and dopamine release, while tryptophan stimulates serotonin which

stimulates sedation in mammals (Schaefer et al., 2001; Leathwood, 1987; as cited in

Schaefer et al., 2001). Amino acid supplementation (alanine, glutamine, and glycine) is

also shown to provide a source for gluconeogenesis as an energy substrate during

times of low nutrient status (Schaefer et al., 2001). However, given the complexities of

nutrient, energy, protein, and ion depletion, single nutrient supplementation will often not

address the entirety of the stress response. Schaefer (1995) found that the use of

vitamin, mineral, and amino acid complexes were more effective in improving meat

quality rather than a single nutrient alone.









Table 2-1. Physiological assessment of stress in transported cattle


Variable
Basal packed cell volume, %


Value
33.8
34.0


Post transport/handling packed cell volume, %


51.3
42.5
37.1


Basal plasma protein concentration, g/100 mL


Post transport/handling plasma protein concentration, g/100 mL


Basal plasma cortisol concentration, ng/mL


Post transport/handling plasma cortisol concentration, ng/mL


13.0
21.5


Source
Lane and Campbell, 1969
Wohlt et al., 1984

Gortel et al., 1992
Parker et al., 2007
Tadich et al., 2004

Parker et al., 2003
Knowles et al., 1999

Parker et al., 2003
Knowles et al., 1999

Elvinger et al., 1992
Mitchell et al., 1988
Alam and Dobson, 1986

Lay et al., 1992
Knowles et al., 1999









Table 2-2. Normal muscle quality characteristics of advanced maturity beef
Variable Value Source
Normal pH 5.5-5.7 Aberle et al,, 2001
Dry, Firm, Dark pH > 5.8 Aberle et al., 2001
Lightness (L*)1'2 35.0 Cranwell et al., 1996
Redness (a*)1'2 23.7 Cranwell et al., 1996
Yellowness (b*)1'2 9.6 Cranwell et al., 1996
Drip Loss, %3 1.3-1.6 Davis et al., 1979
Warner-Bratzler Shear Force, kg 4.9 Cranwell et al., 19962,4
7.5 Davis et al., 19795
1 L* = measure of darkness to lightness (larger value indicates a lighter color); a* = measure of redness (larger value
indicates a redder color); b* = measure of yellowness (larger value indicates more yellow color).
Data from cattle with mean skeletal maturity = E33 and lean maturity = B05
3Data from C-maturity cattle with average USDA quality grade = Commercial0.
4Cows received feed last 56 d prior to harvest.
5Random sampling from C-maturity carcasses from six U.S. packing plants.













7


6.5

T"s


S- -------------


a. -- Normal

----- DFPD
----- -....----PSE

5


4.5 ..
0 5 10 15 20 25

Time Post Mortem (h)


Figure 2-1. The relationship of postmortem pH decline with characteristics of beef
muscle, adapted from Aberle (2001)


Isoelectric Point


4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6
4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6


5.8 6 6.2 6.4


Figure 2-2. The relationship of beef muscle pH to water holding capacity, adapted from
Wismer-Pedersen (1987)











CHAPTER 3
EFFECT OF ON FARM ELECTROLYTE SUPPLEMENTATION ON WEIGHT LOSS,
HYDRATION, STRESS, AND MUSCLE QUALITY


Materials and Methods

Animals and Management

Experiment and data sampling on farm

Sixty culled, lactating dairy cows were used for this study, which was conducted

over 4 d in mid-August, 2009. Ambient temperature ranged from 22 to 320C, with an

average relative humidity of 75% for the live animal portions of the study. Cows ranged

from 17 to 989 days in lactation.

Cows were housed in an open-sided free-stall barn with concrete flooring with

fans and misters for cooling. Test animals originated from two separate locations (Farm

5 and 8) of a 10,000-cow commercial dairy farm in Okeechobee County, Florida (270

12'N, 800 46'W). Cows from both locations had the same genetic base, were milked

three times daily, and were fed a total mixed ration ad libitum.

Cows were milked for the final time 18 h prior to the start of the study. Following

milking, farm management at both locations selected and sorted cull cows from the

lactating herd for use on the trial. Cows were selected based on low milk production,

reproductive inefficiency, and lameness. Cows from farm 8 (n = 30) were loaded by

farm personnel on to 8.5 x 2.13 m livestock trailers at a stocking density of 509 kg/m2

and transported 10 min. Cows were unloaded, comingled with cows from farm 5 and

allowed to rest within the unused free-stall barn with ad libitum access to feed. Cows

were allowed access to water for the entirety of the trial, except while being transported.









At 12 h prior to initiation of the trial, cows were withheld from feed, moved 100 m

to a livestock working area, and processed through a commercial squeeze chute to

determine initial weight, then moved back to the vacant barn. Breed type (Holstein;

Holstein x Jersey) and structural soundness were subjectively evaluated (Scale = 1 to 5;

1 = severe mobility issues; 5 = sound). Cows were randomly placed into two different

holding pens for the duration of the on-farm portion of the study. Initial weight, days in

lactation, and farm of origin was used to stratify cows into two treatment groups; control

(CON) or on-farm electrolyte supplemented (PRE).

At 0500 h on day 1 of the study, all cows were secured in a squeeze chute, ear

tagged, and blood sampled via coccygeal veinipuncture. Blood samples were collected

in 10 mL BD Vacutainer tubes (BD Medical Supplies, Franklin Lakes, NJ) containing

lithium heparin as an anti-coagulant. A portion of the chilled blood sample was

immediately placed into two 70 pL capillary tubes and centrifuged at 1500 rpm for 15

min. The percent solids versus plasma in the capillary tubes was then measured using

a Micro-capillary Reader (Damon/IEC Division, Needham Heights, MA) and averaged

between the two samples to determine packed cell volume (PCV; Bull et al., 2000). The

remaining blood samples were placed on ice and after approximately 30 min, were

centrifuged at 1500 rpm for 15 min. Following centrifugation, two plasma samples were

harvested into 1.5 mL micro-centrifuge tubes and placed on dry ice for immediate

freezing. Samples were transported to the University of Florida laboratory and stored at

-200C until utilized for analysis.

Cows (PRE; n = 30) were orally drenched with an electrolyte solution using a 1000

mL drenching gun. A dry electrolyte powder consisting of dextrose, sodium









bicarbonate, magnesium sulfate, and potassium chloride was diluted in 1.5 L of water

and was administered at a level of 2.4 g per kg of initial body weight (Table 3-1). Cows

(CON; n = 30) were given a placebo volume of 1.5 L of water to simulate stress

associated with drenching activity.

Cows were moved to the livestock working area, and back to the vacant barn in

two randomized groups (n = 30) with the first group being processed from 0500 to 0930

h and the second from 1000 to 1400 h. The area leading to and including the livestock

working chute was shaded, but cows were not shaded following processing and prior to

returning to the vacant barn.

Transport, harvest, antemortem and postmortem data sampling

At 1700 h on day 1, cows (n = 60) were loaded randomly onto two (30 cows in

each) 15.24 x 2.5 m pot-belly trailers and transported 3 h to a commercial beef

processing facility. Cows were unloaded and randomly placed into three well-bedded

holding pens with twenty cows in each and allowed 11 h lairage time with ad libitum

access to water prior to harvest.

At 0330 h on day 2 of the trial, cows were processed through a squeeze chute,

weighed and blood samples collected as described earlier. Cattle were stunned and

humanely harvested according to USDA-FSIS accepted procedures.

All carcass measurements were taken from the left carcass sides at 24 h

postmortem. Fat thickness and LM area was measured at the 12th and 13th rib interface.

Internal fat was removed by plant personnel on the kill floor, thus KPH percentage was

assumed to be 2.5% for all carcasses. Fat thickness, LM area, KPH percentage and

hot carcass weight was used to calculate USDA yield grade (USDA-AMS, 1997).

Skeletal maturity, lean color maturity, and marbling score were evaluated by trained









University of Florida personnel. A 5 cm thick section of LM originating from the 13th rib

interface and inside round, cap off (NAMP 169A) was collected.

Following a 30 min bloom time, objective lean color analysis (L*, a*, and b*) were

collected from the anterior LM end of the removed section and from three

measurements on the medial side of the SM using a Hunterlab Miniscan XE Plus

(Hunter Laboratory, Reston, VA) with an illuminant setting of D65/10 calibrated to a

black tile and white tile. Intramuscular pH was measured from the same location of

respective muscles using a portable self-equilibrating pH meter (HI 99163, Hannah

Instruments U.S.A., Woonsocket, RI). One 2.54 cm steak was cut from the anterior LM

end of the removed section for Warner-Bratzler shear force (WBSF) analysis, vacuum

packaged, stored at 4 2C for 14 d, and frozen at -400C.

From the remaining LM portion, a section of LM trimmed free of external fat (12.24

g 1.55) was removed for drip loss analysis. The LM samples were weighed, identified

and placed in 50 g Whirl-pak bags (Nasco International, Fort Atkinson, WI) and

suspended at 4 2C for 24 h. After 24 h, each sample was reweighed and drip loss

was calculated by dividing the weight difference by initial weight x 100.

Blood Plasma Analysis

Plasma samples were thawed at room temperature for 30 min, and 100 pL of

plasma was utilized to analyze plasma protein (PP) concentration. Concentrations were

measured using a temperature compensated hand-held refractometer (Reichert, Inc.,

Depew, NY).

Warner-Bratzler Shear Force

Frozen steaks were removed, weighed, and thawed for 24 h at 4 2C. Steaks

were then cooked on Hamilton Beach HealthSmart indoor/outdoor grills (Hamilton









Beach, Proctor-Silex, Inc., Southern Pines, NC) that were preheated for 20 min. Steaks

were turned once when an internal temperature of 350C was achieved, and continued

cooking until they reached an internal temperature of 71 C (AMSA, 1995). Internal

temperatures were monitored using a copper-constantan thermocouple (Omega

Engineering Inc., Stamford, CT) placed in the geometric center of each steak, and were

recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc.,

Middleboro, MA). Steaks were then chilled for 24 h at 4 20C. After steaks were

allowed to tempter to room temperature, 6 cores, 1.27 cm in diameter were removed

parallel to the longitudinal orientation of the muscle fibers. The cores were then

sheared perpendicular to the longitudinal orientation of the muscle fibers, using an

Instron Universal Testing machine, Model 1011 (Instron Corportaion, Canton, MA) with

a Warner-Bratzler shear head at a cross-head speed of 200 mm/min.

Statistical Analysis

All results were analyzed as a completely randomized design with individual cow

as the experimental unit for all variables measured. The GLM procedure of Statistical

Analysis System V. 9.2 (2008, SAS Inst. Inc., Cary, NC) was used to test the model.

Farm of origin, soundness score, days in lactation, breed, and the numerical order at

initial processing were used as covariates in the model. Least square means were

calculated for main effect of electrolyte treatment, and separated statistically using pair

wise t-tests (P-DIFF option of SAS) when a significant (P < 0.05) F-test was detected.

Results and Discussion

Weight Loss and Hydration

On-farm electrolyte treatment did not affect absolute body weight loss (P = 0.84)

or weight loss percentage (P = 0.35) during the pre-slaughter period (Table 3-2).









Shorthose and Wythes (1988) estimated that cattle lose approximately .75% of their

body weight per day when feed and water is restricted, and it can be expected that

shrink will increase sevenfold during transport (Jones et al., 1988). In the present study,

percent shrink was considerably greater in both groups than normal transport shrink.

There are multiple factors that could have influenced transport weight loss, such as

water intake prior to transport, gastrointestinal emptying during transit and lairage, and

water intake overnight prior to the second weight measurement (Phillips et al., 1985;

Jones et al., 1988; Warris, 1990). There were 8 h between when cows were unloaded

at the processing facility and when the second weight was taken. Therefore, cows were

allowed ample time to regain a portion of the transport shrink over the 8 h period, which

could alter weight loss results.

Results for PCV as an indication of hydration are reported in Table 3-3. Lane and

Campbell (1969) reported that normal PCV for lactating dairy cows is 33.8% when

ambient temperature averaged 24.0C, suggesting cows within the current study had

elevated, but near normal values when the trial began. The pre-slaughter PCV values

of PRE cows decreased from the initial values and tended (P = 0.06) to differ from CON

cows whose values increased (Table 3-3). This indicates that cows receiving an

electrolyte supplementation stayed more hydrated during transport. This is likely an

effect of increased extracellular and intracellular water retention through the

replenishment of sodium and potassium (Tasker, 1980). These cations play a major

role in maintaining osmotic equilibrium amongst major fluid compartments, and are

diminished when an animal undergoes prolonged stress through salivary, urinary and

fecal excretion, and evaporative water loss through respiration. With increased water









retention and absorption, it restores plasma volume, which is reflected in a lower

percent solids in the blood and a lower packed cell volume.

Plasma Protein Concentration

The PP concentration change did not differ (P = 0.18) between PRE and CON

cows (Table 3-4). However, the PRE cows had a numerically lower increase in the PP

concentration change than CON cows. Initial PP concentrations were elevated for both

PRE and CON cows compared to reports by Knowles et al. (1999) and Parker et al.

(2003) who reported basal PP levels as 7.9 and 6.4 g/100 mL, respectively for lactating

dairy cows, suggesting the stress of initial sampling. These are consistent with findings

by Siebert and Macfarlane (1975) that cattle under stress from heat and dehydration will

have higher PP concentrations due to either decreased plasma volume or mobilization

of protein tissues.

Carcass Traits

Descriptive statistics of carcass traits by treatment are presented in Table 3-5.

There was no effect of electrolyte supplementation on carcass characteristics (P 2 0.32)

with the exception of PRE cows having a lower lean color maturity score (P = 0.02).

Cows utilized for the study exhibited comparable carcass traits to dairy cow carcass

characteristics reported in the 2007 National Market Cow and Bull Beef Quality Audit

(NFBQA; NCBA, 2007). Carcasses from PRE cows tended (P = 0.06) to have a lower

LM pH than CON carcasses (Table 3-6). During normal muscle metabolism, glycogen

is used as a substrate to be converted to lactic acid, thus causing a steady pH decline

following harvest (Lister, 1988). Antemortem depletion of muscle glycogen will result in

insufficient lactic acid production for normal pH decline postmortem. On-farm

electrolyte supplementation likely restored glycogen within the muscle resulting in lower









LM pH. Beef with pH values exceeding 5.8 have greater water holding capacity and a

darker color than normal beef, but is not defined as a classic dark cutter (pH > 6.0)

(Hedrick et al., 1959; Lister, 1988; Immonen, et al., 2000). The pH values for carcasses

in this study were greater than 5.8, a substantially higher value for ultimate pH of normal

beef tissue (Hedrick et al., 1959). The higher than normal pH values were possibly

driven by the stress created by high ambient temperature during the study, handling

cows multiple times during blood collection, weighing, and transportation.

Longissimus muscle from PRE cows had a greater (P = 0.04) drip loss percentage

than like samples from CON cows (Table 3-6). Davis et al. (1979) suggested normal

drip loss for C-maturity beef with a normal 24 h postmortem pH to be between 1.3 to

1.6%. Values in Table 3-6 show that LM from PRE cows had closer to normal drip loss

values than CON cows due to an ultimate pH further from the isoelectric point (Aberle et

al., 2001). However, both groups had below normal drip loss percentages, likely due to

a pH that was above normal.

Hunter L*, a*, and b* values did not differ (P 2 0.11) between treatments at

traditional probability levels for both LM and SM (Table 3-6). However, PRE cows

exhibited a trend of higher L* and a* values, exhibiting lighter and redder LM and SM

than CON cows, suggesting a relationship to the lower, more normal pH exhibited by

PRE cows. Literature suggests that culls cows on feed have LM Hunter L*, a*, and b*

values that range from approximately 35.0 to 36.0, 23.0 to 32.0, and 10.0 to 23.0,

respectively (Cranwell et al., 1996; Patten et al., 2008). Values for LM in Table 3-6

indicate a darker, less red, more yellow color from both CON and PRE cows in the









current study. The darker color can be attributed to the greater light absorbance

associated with elevated postmortem pH.

Warner-Bratzler Shear Force

Warner-Bratzler shear force values were similar (P = 0.23) between LM steaks

from CON and PRE cows (Table 3-7). The measurements in the current study are

indicative of average WBSF values from C-maturity beef of 7.5 kg reported by Davis et

al. (1979). However, Cranwell et al., (1996) documented D-maturity cows on feed for

56 d had an average shear force 4.9 kg. This is more indicative of the cows utilized for

the study as they have been fed a high energy total mixed ration throughout the

lactation period. Shackelford et al. (1991) reported that the threshold to classify young

maturity LM steaks as "slightly tender" by a trained sensory panel is 3.9 kg. The shear

force values recorded in the study were much higher than that of younger maturity beef

(Davis et al., 1979). As chronological age increases collagen becomes less soluble

resulting in cooked meat toughness (Mitchell, et al., 1928).

Steaks from PRE cows tended (P = 0.07) to lose less weight during cooking than

steaks from CON cows (Table 3-7). This was surprising considering steaks from PRE

cows had a lower ultimate pH and a greater drip loss percentage than steaks from CON

cows.

Implications

On-farm electrolyte supplementation has potential to attenuate pre-slaughter

dehydration of cull dairy cows. Cows receiving electrolyte supplementation prior to pre-

slaughter stressors showed a tendency to be more hydrated prior to slaughter. Treated

cows also exhibited a lower postmortem pH, and had a more normal muscle water

holding capacity. The environment animals were exposed to resulted in a very









significant stressor. All cattle in this study displayed greater transport shrink, increased

dehydration, elevated postmortem pH, darker muscle color, and less desirable water

holding capacity than what is expected for cattle during normal marketing conditions.

However, it suggests that electrolyte supplementation, has the ability to mitigate a

portion of the aforementioned effects. Decreasing transport shrink can translate to

increased profits to the producer when cattle are marketed to the processor, and more

acceptable muscle quality will provide a more desirable product to the consumer.



Table 3-1. Ingredients of electrolyte supplement
Ingredient Percent
Dextrose 94.8
Sodium Bicarbonate 2.7
Potassium Chloride 1.5
Magnesium Sulfate 1.0





Table 3-2. Effect of on-farm electrolyte supplementation on pre-slaughter body weight
loss
Treatment1
Item CON PRE SEM2 P-Value
Initial Weight, kg 654.7 636.0 19.2 0.51
Post Transport Weight, kg 593.3 573.7 17.8 0.43
Weight Change, kg -62.0 -63.5 5.0 0.84
Weight loss, % -9.2 -10.2 0.7 0.35
1CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW
2SE of the least squares mean.









Table 3-3. Effect of on-farm electrolyte supplementation on packed cell volume of
whole blood during pre-slaughter period
Treatment1
Item CON PRE SEM2 P-Value
Initial PCV, % 35.85 35.34 0.70 0.62
Pre-slaughter PCV, % 36.40 34.62 0.68 0.08
PCV Change 0.55 -0.72 0.45 0.06
% Change 1.63 -1.74 1.20 0.06
CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW
2SE of the least squares mean.


Table 3-4. Effect of on-farm electrolyte supplementation on blood plasma protein
concentration
Treatment1
Item CON PRE P-Value
Initial plasma protein conc., g/100mL 8.93 0.13 8.95 0.13 0.92
Pre-slaughter plasma protein conc., 9.34 0.12 9.24 0.11 0.60
g/100mL
Concentration change, g/100mL 0.41 0.08 0.24 0.08 0.17
1CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW


Table 3-5. Carcass characteristics by treatment group
Treatment1
Item CON PRE P Value
12th-rib fat, cm 0.50 0.08 0.49 0.08 0.93
LM area, cm2 67.9 2.7 67.6 2.7 0.94
Hot carcass wt, kg 313.8 9.8 304.3 9.8 0.51
Dressing % 53.0 0.7 53.2 0.7 0.83
Calculated YG2 2.8 0.1 2.7 0.1 0.64
Marbling3 408 28 426 28 0.66
Lean Maturity4 426 12 382 12 0.02
Skeletal Maturity4 437 29 417 29 0.63
Overall Maturity4 432 18 407 18 0.32
1CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW
2YG = Yield Grade; calculated using 2.5% KPH.
3Marbling score units: 300 = slight00; 500 = modest0.
4Maturity score units: 200 = B0; 500 = E.









Table 3-6. Effect of on-farm electrolyte supplementation on LM and SM pH and
objective color measurements and LM drip loss
Treatment1
Item CON PRE SEM2 P-Value
LM pH 5.91 5.81 0.04 0.06
SM pH 5.90 5.85 0.03 0.35
LM Drip Loss, % 0.61 1.26 0.21 0.04

LM Lightness (L*)3 32.99 34.38 0.82 0.25
LM Redness (a*)4 18.43 19.25 0.60 0.35
LM Yellowness (b*)5 15.08 15.99 0.45 0.17

SM Lightness (L*)3 28.32 29.80 0.78 0.19
SM Redness (a*)4 20.40 21.95 0.66 0.11
SM Yellowness (b*)5 15.78 17.25 0.63 0.11
1CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW
2SE of the least squares mean.
3L* = measure of lightness to darkness (greater value indicates a lighter color).
4a* = measure of redness (greater value indicates redder color).
b* = measure of yellowness (greater value indicates more yellow color).


Table 3-7. Effect of on-farm electrolyte supplementation on Warner-Bratzler shear force
and cooking loss
Treatment1
Item CON PRE SEM2 P-Value
WBSF, kg 6.36 7.02 0.37 0.23
Cook loss, % -24.24 -22.47 0.66 0.07
1CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water
containing 2.4 g of dry electrolyte per kg BW
2SE of the least squares mean.









CHAPTER 4
EFFECT OF ON-FARM AND POST-TRANSPORT ELECTROLYTE
SUPPLEMENTATION ON WEIGHT LOSS, HYDRATION, STRESS, AND MUSCLE
QUALITY

Materials and Methods

Animals and Management

Experiment and data sampling on farm

Forty-eight culled, lactating Holstein-Friesian dairy cows were used for this study

which was conducted over 4 d in mid-December, 2009. Ambient temperature ranged

from 12 to 170C, with an average relative humidity of 87% for the live animal portion of

the study. Cows ranged from 20 to 439 days in lactation.

Cows were housed in an open-sided free-stall barn with concrete flooring with fans

and misters for cooling. Test animals originated from a 6,400-cow commercial dairy

operation in Gilchrist County, FL (290 45'N, 820 51'W). Cows had the same genetic

base, were milked three times daily, and were fed a total mixed ration ad libitum.

At 18 h prior to the start of the study, farm management selected and sorted cull

cows from the lactating herd for use in the trial, then moved them 50 m to a large dirt

holding pen adjacent to the livestock working area. Cows were culled based on low

milk production, reproductive inefficiency, and lameness. Cows were allowed ad libitum

access to water for the entirety of the trial.

At 12 h prior to treatment administration, cows were moved 50 m to a livestock

working area, and processed through a commercial squeeze chute to determine initial

weight, then moved back to the vacant holding pen. Structural soundness score (Scale

= 1 to 5; 1 = severe mobility issues; 5 = structurally sound) was objectively evaluated.

Initial weight and days in milk was used to stratify cows into three treatment groups;









control (CON), on-farm electrolyte supplemented (PRE), or post-transport electrolyte

supplemented (POST).

At 0500 h the following day, cows were withheld from feed. Cows were moved 50

m to the working area where they were held in an uncovered working pen bedded with

sand. Cows were moved in small groups into a covered, dirt floor working pen which

was ventilated by fans. Cows were then secured in a commercial squeeze chute, ear

tagged, and blood sampled via coccygeal veinipuncture. Blood samples were collected

in 10 mL BD Vacutainer tubes (BD Medical Supplies, Franklin Lakes, NJ) containing

lithium heparin as an anti-coagulant. A portion of the chilled blood sample was

immediately placed into two 70pL capillary tubes and centrifuged at 1500 rpm for 15

min. The percent solids versus plasma in the capillary tubes was then measured using

a micro-capillary reader (Damon/IEC Division, Needham Heights, MA) and averaged

between the two samples to determine PCV (Bull et al., 2000). The remaining blood

samples were placed on ice, and after approximately 30 min, were centrifuged at 1500

rpm for 15 min. Following centrifugation, two plasma samples were harvested into 1.5

mL micro-centrifuge tubers and placed on dry ice for immediate freezing. Samples

were transported to the University of Florida laboratory and stored at -200C until utilized

for analysis.

Cows (PRE; n = 16) were orally drenched with an electrolyte solution using a 1000

mL drenching gun. A dry electrolyte powder consisting of dextrose, sodium

bicarbonate, magnesium sulfate, and potassium chloride was diluted in 1.5 L of water

and was administered at a level of 2.4 g per kg of body weight (Table 4-1). Cows (CON









and POST; n = 16, respectively) were given a placebo volume of 1.5 L of water to

simulate stress associated with drenching activity.

After exiting the chute, cows were released into an uncovered holding pen bedded

with sand, and were moved collectively back to the vacant dirt lot at 0930 h, after all

cows were processed.

Transport and plant electrolyte treatment

At 1400 h, cows (n = 30) were loaded randomly onto a 15.24 x 2.5 m pot-belly

trailer, and the remaining cows (n = 16) were loaded onto an 8.5 x 2.13 m livestock

trailer at 574 kg/m2. Care was taken by farm management to load cows with soundness

issues in the rear compartment of the pot-belly trailer to prevent further injury, as well as

isolate lighter weight cows on the livestock trailer for ease of transport. Two cows in the

POST group were retained by farm management and not utilized for the remainder of

the study. The cows were transported 2 h to a commercial beef processing facility.

Cows were unloaded and randomly placed in two holding pens (n = 23 per pen).

At 1700 h cows were processed through a squeeze chute, weighed, and blood

samples collected as described earlier. Cows (POST; n = 14) were administered an

electrolyte treatment using the previously described procedure, with CON and PRE

cows given a placebo volume of 1.5 L of water simulate drenching associated stress.

Lairage, harvest, and postmortem sampling

Cows were allowed 8 h lairage time following post-transportation sampling. At

0400 h the following day, cows were processed through a squeeze chute, weighed, and

blood samples were collected as described earlier. At 1000 h, cattle were stunned and

humanely slaughtered according to USDA procedures.









Longissimus muscle pH was measured at 3 h postmortem and all other carcass

measurements were taken from the same side at 24 h postmortem. Fat thickness and

LM area was measured at the 12th and 13th rib interface. Internal fat was removed by

plant personnel on the kill floor, thus KPH percentage was assumed to be 2.5% for all

carcasses. Fat thickness, LM area, KPH percentage and hot carcass weight was used

to calculate USDA yield grade (USDA-AMS, 1997). Skeletal maturity, lean color

maturity, and marbling score were evaluated by trained University of Florida personnel.

A 5 cm thick section of LM originating from the 13th rib interface and inside round, cap

off (NAMP 169A) was collected.

Following a 30 min bloom time, objective lean color analysis (L*, a*, and b*) were

collected from the anterior LM end and from three measurements on the medial side of

the SM using a Hunterlab Miniscan XE Plus (Hunter Laboratory, Reston, VA) with an

illuminant setting of D65/10 calibrated to a black tile and white tile. Intramuscular pH

was measured from the same location of respective muscle using a portable self-

equilibrating pH meter (HI 99163, Hannah Instruments U.S.A., Woonsocket, RI). During

fabrication a 5 cm thick portion of the LM was removed, from which a 2.5 cm thick steak

was cut for Warner Bratzler shear force (WBSF) analysis.

From the remaining LM portion, a section of LM trimmed of external fat (12.24 g +

1.55) was removed for drip loss analysis. The LM samples were weighed, recorded and

placed in 50 g Whirl-pak bags (Nasco International, Fort Atkinson, WI) with

corresponding identifications in 4 2 C for 24 h. After 24 h, each sample was

reweighed and drip loss was calculated by dividing the weight difference by initial weight

x 100.









Blood Analysis

Plasma samples were thawed at room temperature for 30 min, and 25 pL of

plasma was used in a commercial EIA kit (Diagnostic Systems Laboratory, Webster,

TX) to determine plasma cortisol concentrations. An additional 100 pL of plasma was

utilized to analyze PP concentration. Concentrations were measured using a

temperature compensated hand-held refractometer (Reichert, Inc., Depew, NY).

Warner-Bratzler Shear Force

Shear steaks were vacuum packaged and aged for 14 d at 4 20C and then frozen

at -400C. Frozen steaks were removed, weighed, and thawed for 24 h at 4 20C.

Steaks were then cooked on Hamilton Beach HealthSmart indoor/outdoor grills

(Hamilton Beach, Proctor-Silex, Inc., Southern Pines, NC) that were preheated for 20

min. Steaks were turned once when an internal temperature of 350C was achieved, and

continued cooking until they reached an internal temperature of 71 C (AMSA, 1995).

Internal temperatures were monitored using a copper-constantan thermocouple (Omega

Engineering Inc., Stamford, CT) placed in the geometric center of each steak, and were

recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc.,

Middleboro, MA). Steaks were then chilled for 24 h at 4 20C. After chill, 6 cores, 1.27

cm in diameter were removed parallel to the longitudinal orientation of the muscle fibers.

The cores were then sheared perpendicular to the longitudinal orientation of the muscle

fibers, using an Instron Universal Testing machine, Model 3343 (Instron Corportaion,

Canton, MA) with a Warner-Bratzler shear head at a cross-head speed of 200 mm/min.

Statistical Analysis

All results were analyzed as a completely randomized design with individual cow

as the experimental unit for all variables measured. The GLM procedure of Statistical









Analysis System V. 9.2 (2008, SAS Inst. Inc., Cary, NC) was used to test the model.

Soundness score and days in lactation were used as covariates in the model.

Orthogonal contrast to compare CON and POST treatments to PRE treatment for

measurements taken immediately following transport were analyzed using a Dunnett's

test. Least square means were calculated for the main effect of electrolyte treatment,

and separated statistically using pair wise t-tests (P-DIFF option of SAS) when a

significant (P < 0.05) F-test was detected.

Results and Discussion

Weight Loss and Hydration

On-farm electrolyte treatment tended to improve absolute weight loss (P = 0.10)

and weight loss percentage (P = 0.06) during transportation for PRE cows compared to

CON and POST cows (Table 4-2). There were no differences in weight loss (P = 0.28)

and weight loss percentage (P = 0.46) during lairage between POST, CON and PRE

cows. Cows receiving POST electrolyte supplementation reported a trend of lower

actual weight loss and weight loss percentage than CON and PRE cows. Treatments

did not differ for absolute weight loss (P = 0.22) or weight loss percentage (P = 0.42)

over the duration of transport and lairage. However, CON cows had numerically greater

weight change and percentage weight loss than electrolyte treated cows. These results

are consistent with work done by Gortel et al. (1992) reporting improvements in weight

loss in beef bulls given electrolyte therapy prior to transport. Gortel et al. (1992)

attributed the lowered weight loss to the additional extracellular fluid volume found in

treated bulls in their study. It is anticipated that the sodium and potassium

supplementation increases cellular osmolarity, allowing for more fluid uptake and

retention at the cellular level. It has also been reported that cattle supplemented with









dietary sodium have increased water intake (Escobosa et al., 1984). Treated cows

could have consumed more water following respective electrolyte treatments, which

would have effects on rumen and gastrointestinal fill, as well as cellular water

absorption.

Cows from trial 2 had greater transport shrink compared to cows from trial 1. This

was in large part attributed to when cows were removed from feed prior to initiation of

the studies. Cows from trial 1 had a 12 h period in which feed was deprived, which

likely resulted in a large portion of weight loss prior to starting the study, as compared to

trial 2, in which cows had access to feed up until initial samples were taken. Thus, cows

from trial 2 had more available weight to be lost via gastric emptying over the duration of

the study. Cows from trial 1 likely excreted much of the rumen and gastrointestinal

contents during the 12 h before the study began.

Results for PCV as an indication of hydration are reported in table 4-3. The post-

transport PCV change for PRE cows did not differ (P = 0.49) from CON and POST

cows, although PRE cows exhibited a trend of a lower numerical increase in PCV

change than CON and POST groups. There were no statistical differences (P = 0.22) in

PCV change after lairage between POST cows and CON and PRE cows. However,

POST cows exhibited a trend of decreased PCV change after lairage, while both CON

and PRE groups showed a trend to increase. Over the duration of transport and

lairage, there were no differences (P = 0.29) in PCV change between treatments.

Again, however, PRE and POST cows had lower increases in PCV change than CON

cows.









Initial PCV percentage values of all cows in this study were substantially lower

than those reported in Chapter 3 (Table 3-3). Additionally, the PCV of these cows was

similar to the value of 33.8%reported by Lane and Campbell (1969) for lactating dairy

cows in a thermoneutral environment. The difference in ambient temperature impacted

the differences in initial PCV percentage value between the two trials. Cows from trial 2

also required less handling due to more appropriate working facilities, were kept on dirt

rather than concrete, and were exposed to fans during processing, compared with cows

from trial 1; all of which could have impacted physiology.

Plasma Protein and Cortisol Concentration

Following transport, PRE cows had a greater PP concentration increase (P = 0.03)

than CON and POST cows (Table 4-4). Following lairage, POST cows had a decrease

in PP concentration change which differed (P < 0.01) from CON and PRE cows. Both

CON and PRE treatments had an increase. Over the duration of transport and lairage,

POST cows had a lower (P < 0.01) PP concentration change than CON and PRE cows.

All cows had initial PP concentrations similar to basal levels reported by Knowles

et al. (1999) and Parker et al. (2003). Additionally, cows in the current trial had

markedly lower initial PP values than cows in Chapter 3 (Table 3-4), complimenting the

results for PCV suggesting cows from trial 2 were subjected to a less stressful

environment. Results from PP concentration change suggest cull dairy cows should be

supplemented after transport to the slaughter facility.

During transportation, there was no difference (P = 0.98) between PRE and CON

and POST treatments in cortisol concentration change, however PRE cows tended (P=

0.09) to have a higher initial plasma cortisol concentration prior to transport than CON

and POST cows (Table 4-5). During lairage, there was no difference (P = 0.13)









between treatments in cortisol concentration, however POST and PRE cows appeared

to have a trend of lower plasma cortisol concentration increases compared to CON

cows (Table 4-5). Over the duration of transportation and lairage, cortisol concentration

changes did not differ (P = 0.58) between treatments, however, PRE and POST treated

cows again exhibited a trend of lower numerical cortisol concentration increases (Table

4-5).

Cortisol concentrations were greater than reports for cortisol concentrations of

lactating dairy cows reported by multiple authors (Lay et al., 1992; Knowles et al.,

1999). The findings for cows from this study to have normal PCV values but greater

than normal PP concentrations are likely affected by the greater than normal plasma

cortisol concentrations (Smith and Hamlin, 1970; Siebert and Macfarlane, 1975).

Meat Quality

Descriptive statistics of carcass traits by treatment are presented in Table 4-6.

There were no differences (P 2 0.11) between treatments with carcass characteristics,

with the exception of marbling score (P = 0.03). However, results do not indicate that

electrolyte supplementation caused an improvement in marbling score. Cows utilized

for the study exhibited comparable carcass traits to dairy cow carcass characteristics

reported in the 2007 NFBQA (NCBA, 2007). Pre-slaughter electrolyte supplementation

did not affect (P 2 0.27) LM or SM pH or objective lean color (Table 4-7). Longissimus

samples from POST carcasses tended to have less drip loss (P = 0.09) than CON and

PRE carcasses (Table 4-7). Carcasses from trial 2 had markedly lower, more normal

intramuscular pH values than those from trial 1, again suggesting a less stressful

environment pre-slaughter (Table 3-6). Also, the shortened feed withdrawal period for

cows from trial 2 likely allowed for more availability of muscle glycogen, thus









contributing to less variability in lean quality attributes. The similar pH values between

treatments led to similar objective lean color values (Table 4-7; Page et al., 2001).

Warner-Bratzler Shear Force and Cooking Loss

Pre-slaughter electrolyte treatment did not effect WBSF values (P = 0.87) or

cooking loss (P = 0.17) of LM steaks (Table 4-8). Longissimus muscle steaks from trial

2 had WBSF values that would be considered very tough (Shackelford et al., 1991).

Implications

Electrolyte supplementation had a greater effect on reducing body weight shrink in

the current study than trial 1. Pre-slaughter electrolyte treatment improved the change

in packed cell volume percentage and plasma protein concentration compared to

control cows, suggesting supplemented cows were more hydrated and mobilized less

tissue protein. Specifically, cows given post-transport supplementation had better PCV

and PP results than pre-transport supplemented cows. Electrolyte treatment had no

effect on any measurement of lean quality or carcass characteristics. All treatments

exhibited normal muscle pH and water holding capacity.

The differences in ambient temperature and handing stress between trial 1 and 2

likely had a major impact on weight loss and hydration variables, as well as ultimate

intramuscular pH and water holding capacity between treatments. Consequently, it is

expected that dietary electrolyte therapy is more efficacious when supplemented during

periods of high heat stress, rather than more temperate environments.

The results from this research lead to the question, would electrolyte

supplementation both pre- and post-transport have an additive effect on results? More

research remains to be conducted on multiple supplementations for this to be proven.

The current results suggest that pre-slaughter electrolyte treatment has the potential to









reduce live weight loss during transportation and lairage when administered either prior

to transportation or lairage. If weight loss is minimized in tissues associated with the hot

carcass, there is potential for increased revenue to the producer when marketing cows

to the processor on the rail.

Table 4-1. Ingredients of electrolyte supplement
Ingredient Percent
Dextrose 94.8
Sodium Bicarbonate 2.7
Potassium Chloride 1.5
Magnesium Sulfate 1.0









Table 4-2. Effect of pre and post-transport electrolyte supplementation on weight loss during transport and lairage
Treatment1 P-Values
CON PRE POST CON + POST PRE vs.
Item (n = 16) (n = 16) (n = 14) (n = 30) Treatment Others
Initial weight, kg 726.0 27.6 730.3 33.8 0.90
Post-transport weight, kg 671.4 23.0 670.3 23.0 628.6 25.0 650.0 28.6 0.38 0.48
Pre-harvest weight, kg2 642.4 22.9 639.5 22.9 624.2 24.9 -0.85

Transport weight loss, kg 57.6 13.0 -79.6 13.0 0.10
Transport shrink, % -8.58 1.99 -12.45 1.99 0.06
Lairage weight loss, kg3 28.9 12.0 30.8 12.0 4.5 13.1 -0.28
Lairage shrink, % -4.41 1.96 -4.98 1.96 -1.52 2.12 -0.46
Total weight change, kg4 109.6 10.9 88.4 10.9 83.1 11.9 -0.22
Total shrink, % -17.07 1.89 -13.77 1.89 -14.13 2.05 0.42-
CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched with 1.5 L of water containing 2.4
g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry
electrolyte per kg BW after transport.
2Measured after 8 h lairage period, approximately 3 h prior to harvest.
3Weight loss over 8 h lairage period after second electrolyte or placebo supplementation was administered.
4Weighloss from first electrolyte or placebo treatment to approximately 3 h prior to harvest.









Table 4-3. Effect of pre and post-transport electrolyte supplementation on packed cell volume (PCV)
Treatment1 P-Values
CON PRE POST CON + POST PRE vs.
Item (n = 16) (n = 16) (n = 14) (n = 30) Treatment Others
Initial PCV, % 32.38 0.91 32.35 1.12 0.97
Post-transport PCV, % 33.83 0.83 33.09 0.83 32.90 0.90 33.37 1.03 0.72 0.79
Pre-harvest PCV, %2 34.72 0.78 33.73 0.78 32.54 0.84 0.18

Transport PCV change, 0.60 0.52 0.96 0.52 0.49
%
Lairage PCV change, %3 0.89 0.49 0.64 0.49 -0.36 0.54 0.22
Total PCV change%4 1.83 0.51 1.24 0.51 0.62 0.55 0.29
1CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched with 1.5 L of water containing
2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry
electrolyte per kg BW after transport.
2Measured after 8 h lairage period, approximately 3 h prior to harvest.
3PCV change over 8 h lairage period after second electrolyte or placebo supplementation was administered.
4PCV change from first electrolyte or placebo treatment, until approximately 3 h prior to harvest.









Table 4-4. Effect of pre and post-transport electrolyte supplementation on plasma protein (PP) concentration
Treatment1 P-Value
CON + PRE
CON PRE POST POST vs.
Item (n = 16) (n = 16) (n = 14) (n = 30) Treatment Others
Initial plasma protein conc., g/100 7.92 0.20 8.27 0.25 0.18
mL
Post transport plasma protein conc., 8.39 0.20 8.53 0.20 9.07 0.22 8.73 0.25 0.07 0.43
g/100 mL
Pre-harvest plasma protein conc., 8.54 0.22 8.70 0.22 8.81 0.23 -0.69
g/100 mL
Transport PP change, g/100 mL2 -0.61 0.07 0.45 0.07 0.03
Lairage PP change, g/100 mL3 0.15 0.08a 0.17 0.08a -0.26 0.08b < 0.01
Total PP change, g/100 mL4 0.61 0.08a 0.78 0.08a 0.19 0.09b < 0.01
CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched with 1.5 L of water containing
2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry
electrolyte per kg BW after transport.
2Measured after 8 h lairage period, approximately 3 h prior to harvest.
3Change over 8 h lairage period after second electrolyte or placebo supplementation was administered.
4Change from first electrolyte or placebo treatment, until approximately 3 h prior to harvest.
a,b,c Within a row, values lacking a common superscript letter differ (P < 0.05).











Table 4-5. Effect of pre and post-transport electrolyte supplementation on plasma cortisol concentration
Treatment1 P-Value
PRE
CON PRE POST CON + POST vs.


Item (n = 16) (n = 16) (n = 14) (n = 30) Treatment Other
Initial cortisol conc., pg/dL 7.62 1.46 5.04 1.46 0.09
Post-transport cortisol conc., 4.83 1.75 8.72 1.75 7.07 1.89 5.95 2.17 0.30 0.21
pg/dL
Pre-harvest cortisol conc., 13.12 2.12 11.02 2.12 9.12 2.30 0.45
pg/dL
Transport cortisol change, -1.07 2.70 1.00 2.70 0.9E
pg/dL 2
Lairage cortisol change, 8.29 2.34 2.31 2.34 2.06 2.54 0.13
pg/dL 3
Total cortisol change, 6.94 2.39 3.38 2.39 5.39 2.59 0.58
pg/dL 4
CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched with 1.5 L of water containing
2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry
electrolyte per kg BW after transport.
2Measured after 8 h lairage period, approximately 3 h prior to harvest.
3Change over 8 h lairage period after second electrolyte or placebo supplementation was administered.
4Change from first electrolyte or placebo treatment, until approximately 3 h prior to harvest.
a,b,c Within a row, values lacking a common superscript letter differ (P < 0.05).


rs









Table 4-6. Carcass characteristics by treatment group
Treatment1
Item Control PRE POST P Value
12th-rib fat, cm 0.27 0.07 0.30 0.07 0.13 0.07 0.22
LM area, cm2 58.4 3.3 60.2 3.3 57.3 3.6 0.84
Hot carcass wt, kg 328.7 11.9 321.2 11.9 309.0 12.9 0.53
Dress % 51.1 1.1 50.1 1.1 49.8 1.2 0.65
Calculated YG2 3.1 0.1 3.0 0.1 2.9 0.2 0.58
Marbling3 392 39 459 39 302 42 0.03
Lean Maturity4 427 26 438 26 490 28 0.23
Skeletal Maturity4 414 38 418 38 516 41 0.14
Overall Maturity4 418 30 430 30 506 32 0.11
CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally
drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to
transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte
per kg BW after transport.
2YG = Yield Grade; calculated using 2.5% average KPH.
3Marbling score units: 300 = slight00; 500 = modest0.
4Maturity score units: 200 = B0; 500 = E.










Table 4-7. Effect of pre and post-transport electrolyte supplementation on pH and objective color measurements of the
LM and semimembranosus and LM drip loss


Item
3 h postmortem LM pH
24 h postmortem LM pH
24 h postmortem SM pH
LM drip loss, %

LM Lightness (L*)2
LM Redness (a*)3
LM Yellowness (b*)4


CON
7.02 0.07
5.67 0.03
5.64 0.03
1.79 0.27

22.62 0.99
25.28 0.77
20.41 0.62


Treatment1
PRE
7.14 0.07
5.69 0.03
5.66 0.03
1.20 0.27

22.10 0.99
24.17 0.77
19.11 0.62


POST
7.03 0.07
5.68 0.03
5.67 0.03
0.91 0.30

20.63 1.07
24.51 0.83
19.17 0.67


SM Lightness (L*)2 20.42 1.30 19.95 1.30 21.48 1.41 0.72
SM Redness (a*)3 25.68 1.04 27.55 1.04 25.95 1.13 0.40
SM Yellowness (b*)4 19.67 0.80 19.96 0.80 20.23 0.87 0.89
CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched with 1.5 L of water containing 2.4
g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry
electrolyte per kg BW after transport.
2L* = measure of darkness to lightness (greater value indicates a lighter color)
3a* = measure of redness (greater value indicates a redder color);
4b* = measure of yellowness (greater value indicates more yellow color).


P-Value
0.43
0.88
0.81
0.09

0.39
0.58
0.27









Table 4-8. Effects of pre and post-transport electrolyte supplementation on Warner-
Bratzler shear force and cooking loss
Treatment1
Item CON PRE POST P-Value
WBSF, kg 9.14 0.47 9.39 0.47 9.48 0.51 0.87
Cooking loss, % -23.64 0.97 -21.49 0.97 -23.95 1.05 0.17
1CON, orally drenched with 1.5 L of water pre and post-transport; PRE, orally drenched
with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport;
POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg
BW after transport.









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BIOGRAPHICAL SKETCH

Travis Arp was born in Madison, Wisconsin in 1986, the son of Steve and Betty

Arp. He was raised, along with his older sister and younger brother, on the University of

Wisconsin Beef Cattle Research farm, which his father managed. His family also

owned and operated a small herd of purebred Gelbvieh and commercial cattle in north

central Missouri. He graduated from Poynette High School, Poynette, Wisconsin in

June 2004. While working on his undergraduate degree at the University of Missouri,

he participated on the intercollegiate meat and livestock evaluation teams, and also

worked at the University of Missouri Middlebush and South Farms, as well as the

Missouri Cattlemen's Association for three years. He received his Bachelor of Science

degree in agriculture economics in May 2008. He is currently a graduate assistant

finishing a Master of Science degree in the Department of Animal Sciences at the

University of Florida.





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1 EFFECTS OF PREHARVEST ELECTROLYTE SUPPLEMENTATION ON THE HYDRATION AND MEAT QUALITY OF CULL DAIRY COWS By TRAVIS STEVEN ARP A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Travis Steven Arp

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3 To my parents for their endless support and guidance throughout my education

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4 ACKNOWLEDGMENTS I would like to thank Dr. Chad Carr firs t and foremost for his guidance and advice throughout the duration of my graduate degree at the University of Florida. Not only has Chad acted as an outstanding advisor and mentor while working on my masters degree, but has also been a tremendous friend s ince my time as an undergraduate at the University of Missouri. He made my transition from the Midwest to Florida much more comfortable and he and his wife Cathy have become two of my closest friends in the process. I have learned so much from Chad durin g my graduate work and will continue to call upon him as a mentor and friend as I continue through graduate school and my future career, regardless of where it takes me. I would also like to thank Dr. Dwain Johnson and Dr. Todd Thrift from my graduate comm ittee as well as Mr. Larry Eubanks from the meat science department. Each has provided me with outstanding input to my research and each have a great understanding of the beef industry. That insight has given me a much better perspective in my research and a better understanding of the meat and beef industry, particularly how it associates with the industries in Florida and the Southeast. The knowledge I have gained from my entire committee has given me a more well rounded understanding of the regional difference s among beef production systems in the United States. Special thanks go to all the graduate and undergraduate students who helped me carry out both of my research projects; particularly Trey Warnock and Drew Cotton for their help during the Augus t study. Those were three of the hardest, hottest, and most miserable days of the summer, and we would not have been able to complete our first trial without their help. Also, thank you to John Michael Gonzalez, Kalyn Bischoff, Will

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5 Sapp, Richelle Miller Crystal Hale and Melissa Miller for their help during the December study. Their help made the second trial run much more smoothly and reduced the stress levels for everybody involved. I am deeply indebted to Trey Warnock, Brett Wheeler, Drew Cotton, J ohn Michael Gonzalez, Tera Loyd, and Kalyn Bischoff for their friendship over the past two years, along with the many other friendships I have developed while at UF. They have offered a great amount of support and relief during our graduate programs and h ave made the stress of class and research much more enjoyable. Finally, I would like to give the biggest thanks to my family. My parents have always been tremendously encouraging for me to follow my aspirations regardless of where they take me. It has been their constant guidance and encouragement that has ood behind my decisions and have let me shape my own future while pushing me to be the best at everything I did and helping me in whatever way possible. I am truly blessed to have such an understanding and supportive family that has allowed me to follow my goals, even though they have taken me to the opposite side of the country. I owe any amount of success to my mother and father, and app reciate the support of my brother and sister, grandparents, and the rest of my family and friends over the years.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ 4 L IST OF TABLES ................................ ................................ ................................ ........... 8 LIST OF FIGURES ................................ ................................ ................................ ........ 9 ABSTRACT ................................ ................................ ................................ .................. 10 CHAPTER 1 INTRODUC TION ................................ ................................ ................................ ... 12 2 REVIEW OF LITERATURE ................................ ................................ ................... 15 Introduction ................................ ................................ ................................ ............ 15 Animal Welfare ................................ ................................ ................................ ...... 16 Issues and Regulations ................................ ................................ ................... 16 Animal Handling ................................ ................................ .............................. 19 Stress Physiolo gy ................................ ................................ ................................ .. 21 Physiological Indicators of Stress ................................ ................................ .... 21 Meat Quality Stress Indicators ................................ ................................ ......... 24 Livestock Marketing and Stress Attenuation ................................ .......................... 27 Stress During the Pre Slaughter Period ................................ .......................... 27 Attenuation of Transport a nd Handling Stress ................................ ................. 29 3 EFFECT OF ON FARM ELECTROLYTE SUPPLEMENTATION ON WEIGHT LOSS, HYDRATION, STRESS, AND MUSCLE QUALITY ................................ ..... 36 M aterials and Methods ................................ ................................ .......................... 36 Animals and Management ................................ ................................ ............... 36 Experiment and data sampling on farm ................................ ..................... 36 Transport, harvest, antemortem and postmortem data sampling .............. 38 Blood Plasma Analysis ................................ ................................ .................... 39 Warner Bratzle r Shear Force ................................ ................................ .......... 39 Statistical Analysis ................................ ................................ .......................... 40 Results and Discussion ................................ ................................ ......................... 40 Weight Loss and Hydration ................................ ................................ ............. 40 Plasma Protein Concentration ................................ ................................ ......... 42 Carcass Traits ................................ ................................ ................................ 42 Warner Bratzler Shear Force ................................ ................................ .......... 44 Implications ................................ ................................ ................................ ........... 44

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7 4 EFFECT OF ON FARM AND POST TRANSPORT ELECTROLYTE SUPPLEMENTAT ION ON WEIGHT LOSS, HYDRATION, STRESS, AND MUSCLE QUALITY ................................ ................................ ............................... 48 Materials and Methods ................................ ................................ .......................... 48 Animals and Management ................................ ................................ ............... 48 Experiment and data sampling on farm ................................ ..................... 48 Transport and plant electrolyte treatment ................................ .................. 50 Lairage, harvest, and postmortem sampling ................................ ............. 50 Blood Analysis ................................ ................................ ................................ 52 Warner Bratzler Shear Force ................................ ................................ .......... 52 Statistical Analysis ................................ ................................ .......................... 52 Results and Discussion ................................ ................................ ......................... 53 Weight Loss and Hydration ................................ ................................ ............. 53 Plasma Protein and Cortisol Concentration ................................ ..................... 55 Meat Quality ................................ ................................ ................................ .... 56 Warner Bratzler S hear Force and Cooking Loss ................................ ............. 57 Implications ................................ ................................ ................................ ........... 57 LIST OF REFERENCES ................................ ................................ .............................. 66 BIOGRAPHICAL SKETCH ................................ ................................ ........................... 75

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8 LIST OF TABLES Table page 2 1 Physiological assessment of stress in transported cattle ................................ ... 33 2 2 Normal muscle quality characteristics of advanced maturity beef ...................... 34 3 1 Ingredients of electrolyte supplement ................................ ................................ 45 3 2 Effect of on farm electrolyte supplementa tion on pre slaughter body weight loss ................................ ................................ ................................ ................... 45 3 3 Effect of on farm electrolyte supplementation on packed cell volume of whol e blood during pre slaughter period ................................ ................................ ...... 46 3 4 Effect of on farm electrolyte supplementation on blood plasma protein concentration ................................ ................................ ................................ ..... 46 3 5 Carcass characteristics by treatment group ................................ ....................... 46 3 6 Effect of on farm electrolyte supplementation on LM and SM pH and objective color measurements and LM drip loss ................................ ................ 47 3 7 Effect of on farm el ectrolyte supplementation on Warner Bratzler shear force and cooking loss ................................ ................................ ............................... 47 4 1 Ingredients of electrolyte supplement ................................ ................................ 58 4 2 Effect of pre and post transport electrolyte supplementation on weight loss during transport and lairage ................................ ................................ ............... 59 4 3 Effect of pre and post transport electrolyte supplementation on packed cell volume (PCV) ................................ ................................ ................................ .... 60 4 4 Effect of pre and post transport electrolyte supplementation on plasma protein (PP) concentration ................................ ................................ ................. 61 4 5 Effect of pre and post transport electrolyte supplementation on plasma cortisol concentration ................................ ................................ ........................ 62 4 6 Carcass characteristics by treatment group ................................ ....................... 63 4 7 Effect of pre and post transport electrolyte supplementation on pH and objective color measurements of the LM and semimembranosus and LM drip loss ................................ ................................ ................................ ................... 64 4 8 Effects of pre and post transport electrolyte supplementation on Warner Bratzler shear force and cooking loss ................................ ................................ 65

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9 LIST OF FIGURES Figure page 2 1 The relationship of postmortem pH decline with characteristics of beef muscle, adapted from Aberle (2001) ................................ ................................ 35 2 2 The relationship of beef muscle pH to water holding capacity, adapted from Wismer Pedersen (1987) ................................ ................................ .................. 35

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10 Abstract of Thesis Presented to the Graduate Scho ol of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EFFECTS OF PREHARVEST ELECTROLYTE SUPPLEMENTATION ON THE HYDRATION AND MEAT QUALITY OF CULL DAIRY COWS By Travis Steven Arp Aug ust 2010 Chair: Chad Carr Major: Animal Science s Transportation and handling of cattle prior to slaughter are stressors which ca n impact weight change and post mortem muscle quality. Electrolyte supplementation has been evaluated extensively with growin g and finishing cattle, but little to no work has been reported with cull cows. The object ive of the two studies was to determine the effects of pre and post transport el ectrolyte supplementation on weight loss, hydration and meat quality in cull dairy c ows. In the first study, s ixty cull dairy cows (644.3 121.9 kg) were stratified by body weight, days of lactation, and farm of origin into two treatment groups (n=30). At 0500 cows were drenched with a solution of 2.4 g of dry electrolyte per kg of ini tial body weight, and diluted in approximately 1.5 L of water. Dry electrolyte was comprised of dextrose, sodium bicarbonate, magnesium sulfate and potassium chloride. Control group was given a placebo volume (1.5 L) of water. A t 1700 cows were transpor ted 3 h to a non fed beef processor, unloaded and allowed 8 h of lairage time with access to water prior to slaughter. Body weight and blood were collected from cows prior to treatment and slaughter. Treated cows tended to remain more hydrated than contr ol cows from dosage till slaughter as per a greater decrease in packed cell volume (PCV; P = 0.06). Also, LM samples from treated cows exhibited

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11 greater drip loss ( P < 0.0 5) and tended to have a lower pH ( P = 0.06 ) than samples from control cows. In the second study, forty eight cull dairy cows (712.8 120.4 kg) were stratified by weight and days of lactation into three treatments (n=16). Cows were drenched with electrolyte treatment prior to transport or following transport using the same procedures a s the first study. Weights and blood samples were taken prior to and after transport, and prior to slaughter, and meat quality evaluations were taken at 24 hr postmortem. No significant treatment effect on weight loss and hydration, indicated by PCV, was observed. However, cows treated after transport had a significantly lower plasma protein concentration change ( P < 0.01) after lairage and during the duration of transport and lairage. There were strong numerical indicators that results are consistent w ith that of the first study in regards to packed cell volume, as well as more improved weight loses after transport and lairage. Our results showed, however, that cows started and remained more hydrated over the duration of the trial compared to cows from trial 1, indicated by lower PCV and PP values; likely attributed to less environmental and handling stress during the live animal portion of the study. These results show potential for electrolyte supplementation in cull cows to mitigate transport and han dling stress to improve animal hydration and meat quality.

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12 CHAPTER 1 INTRODUCTIO N (NC BA, 1999). Of that percentage, about one third is comprised of the harvest of cull dairy cows (NCBA, 1999). Dairy cows are culled from the herd for various reasons, including: reproductive inefficiency, low milk yield, mastitis, and lameness (Hadley et a l., 2006). Many cull cows are marketed through an auction market prior to being harvested at non fed beef processing facilities. A large portion of Florida cull cows are sold directly to the processor due to their close proximity and the economy of scale The marketing of cattle can require long transport times and excessive handling. According to the 2007 National Market Cow and Bull Beef Quality Audit, loads of non fed cattle traveled an aver age of 5.9 h to beef processing facilities, with maximum transport times of up to 32 h (NCBA, 2007). Livestock often go without water or feed during transportation, and are limited to only water when held in lairage prior to slaughter. Transportation, ex posure to a new environment and novel animals, and weather extremes, all can and will induce a stress response from the animal (Grandin, 1997). The stress response is characterized by the release of the catecholamines, epinephrine and norepinephrine, from the adrenal medulla which increases heart rate and blood pressure (Knowles and Warris, 2000). The catecholamines also induce a signaling cascade along the hypothalamic pituitary adrenal axis that releases various hormones that effect the mobilization of body tissues and depletion of energy stores during times of stress through lipolysis, glycogenolysis, and protein catabolism (Selye,

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13 1939). This leads to a negative energy balance, dehydration and weight loss during transport, along with decreases in dres sing percentage and carcass yield. The autonomic stress response and its relationship with elevated postmortem pH and dark cutting beef has been well documented (Knowles et al., 1999). Multiple studies have been done to attenuate the effects of transport stress in finished cattle through the use of electrolyte supplementation and pre slaughter conditioning regimens. Providing livestock with an energy, ion, or amino acid supplement following stressful periods can aid in the recovery of muscle glycogen depl etion, which can prevent dry, firm, and dark meat quality issues (Cole and Hutcheson, 1985; Schaefer et al., 1997; Schaefer et al., 2001). Furthermore, reestablishing the sodium and potassium ion balance within the body will aid in the re absorption of in tracellular water (Tasker, 1980) and result in improved hydration, decreased weight loss and improved carcass yield during transport and harvest (Schaefer et al., 1997). A lactating dairy cow is fed a high energy diet during production; withholding a cow f rom feed prior to transportation and slaughter will result in an energy deficit. The combination of a dietary energy deficit, the stress of a full udder, and all other pre slaughter stressors makes a cull dairy cow an ideal subject for research to improve non fed beef quality through stress attenuation. The objectives of the current study were to assess the impact of dietary electrolyte supplementation on weight loss, stress, hydration, and meat quality of cull dairy cows when supplemented prior to and imm ediately following transportation to harvesting facilities. It is hypothesized that electrolyte treatment will allow cows to remain more

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14 hydrated, lose less weight during marketing, and improve muscle pH and objective color measurements.

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15 CHAPTER 2 REVIEW OF LITERATURE Introduction The 1999 National Market Cow a nd Bull Beef Quality Audit (NFBQA ) stated that culled annually; ultimately accoun ting for approximately 15 % of th e total United States beef production (NCBA, 1999). Nearly 75% of non fed beef in the U.S. is generated by culls cows; half of which is from slaughtered dairy cows, thus accounting for over 5% of all U.S. beef production (NCBA, 1999). Much of the product derived from the slaughter of non fed cattle is used for the production of ground beef, which accounts for nearly 45% of the beef consumed in the U.S. (NCBA, 1999). However, the audit also showed that non fed beef packers will market up to 75% of cow or bull carcasses as whole muscle cuts for roast beef, deli meats or steaks and roasts at low price food service facilities (NCBA, 1999). Due to the impact the cull cow industry has on beef production, ensuring the welfare of cull cows is important for catt le producers and packers. Dairy c attle in production are culled for a variety of reasons; old age, reproductive inefficiency, and lameness Specifically, Hadley et al. (2006) reported that injury, reproduction, production, and mastitis issues represent the most prevalent reasons for dairy cows leaving the herd. T hese and the other multiple culling factors potentially relate to issues that result in condemnation of the viscer a, head, hide, or whole carcass. However, less than 1% of non fed cattle are co ndemned during antemortem and postmortem inspection, respectively (NCBA, 2007). Much of the variation in carcass merit and end product quality is caused by the challenges incurred during mark et ing and transport to slaughter. From the time an

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16 animal leaves the farm until it is slaughtered, there are a multitude of stressors which are encountered. Animals can encounter psychological stress from restraint, transport, handling, and novelty, or physical stress from hunger, thirst, fatigue, injury or thermal ex tremes (Grandin 1997). All of these can affect antemortem and early postmortem muscle metabolism, ultimately impacting meat quality (Huff Lonergan and Lonergan, 2005). Feed and water restriction during the pre slaughter period can cause severe weight los s and decreases in dressing percent (Jones et al., 1988). The increasing importance of p erception of animal agriculture and the economic significance of the previously mentioned traits have led to the need for more research evaluating live stock during the pre slaughter period. The use of electrolyte supplementation and pre slaughter conditioning treatments have shown to improve several measures of stress hydration, and muscle quality in fed steers and heifers (Schaefer, 2001; Schaefer et al., 2006). However, few studies have been conducted utilizing cull cows. Animal Welfare Issues and Regulations Animal agriculture faces conti nued pressure from animal activist groups and speculation from the public on the practices involved in the packi ng industry. The majority of livestock producers provide excel lent husbandry. However, t he isolated incidents of poor stewardship that are broadcast nationally reson ate amongst the public and increase the scrutiny on all of animal agriculture. A ll packer s are required to adhere to the Humane Slaughter Act (USDA FSIS, 2009 a ), and almost all utilize humane handling guidelines set forth by the American Meat Institute (AMI, 2005). Of particular importance is that cattle are rendered

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17 insensible to pain prior to exsanguination after a proper stunning procedure has been completed. Prior to and proceeding slaughter, all livestock and carcasses are inspected for potential health problems that could affect food safety (USDA FSIS, 2009b). Livestock are observed bo th at rest and in motion before entering the plant, and a thorough inspection of the head, viscera, and carcass is conducted after exsanguination (USDA FSIS, 2009b). The Recommended Animal Handling Guidelines and Audit Guide (AMI, 2005) outlines procedure s for producers and packers to minimize welfare risk during handling and transportation of livestock. These include: facility assembly and setup, proper loading, unloading, and movement, and humane stunning and postmortem handling (AMI, 2005). All antemo rtem and postmortem measures are taken to ensure animal welfare and food safety. Broom (1991) defines welfare as Multiple studies have shown that the welfare associated with sound stockmanship p ractices allow animals to produce at optimal levels (Grandin, 2003). Therefore, livestock producers and packers have an imbedded interest in utilizing good stockmanship practices. Transportation, comingling, handling, and lairage pr ior to slaughter are all stressors which can impact animal health and meat quality (Grandin, 1997). The issue of non cull cow industry. The United States Department of Agriculture Food Safety and Inspection Ser vice (USDA FSIS, 2004) defines non ambulatory as : A nimals that cannot rise from a recumbent position or that cannot walk, including but not limited to those with broken appendages, severed tendons or ligaments, nerve paralysis, a fractured vertebral co lum n, or metabolic conditions.

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18 S tate and federal legislation has been enacted over the past two decades to prohibit the buying, selling, and receiving of downer cattle in the United States, spurred by media footage of mistreated downer cows in California in 1 993 (Stull et al., 2007). However, a federal ban on the slaughtering of all downer cows in the U.S. was not enacted until after the first confirmed case of Bovine Spongiform Encephalopathy (BSE) in the United States on December 23, 2003 (Stull et al., 200 7). These policies have been met with both praise and criticism from producers and packers as it improves the safety of our food supply, but has a negative economic impact on producers by eliminating downer cows that are simply injured and still acceptabl e for human consumption. A common criticism of the beef industry has been the treatment of downer cattle at slaughter facilities. T he American Veterinary Medical Association has established best management practices for handling downer cows (Stull et al ., 2007). However, there has continued to be cases of mistreated down cows (Stull et al., 2007). These instances are often highly publicized by national media and continue to cause skepticism of the practices of producers and packers, as well as the safe ty of the U.S. food supply. The most significant event occurred in February, 2008, when the non fed beef packer, Hallma rk/Westland Meat Packing Co. in Chino, C A was required to recall over 143 million pounds of beef products due to inhumane handling of no n ambulatory cows (USDA FSIS, 2008). This became a policy changing event in the U.S. meats industry, and resulted in the largest ever recall by FSIS as well as the only ever recall for a non food safety concern Additionally, this event led to the incre ased attention on humane handling and slaughter set forth by FSIS in 2008 (USDA FSIS, 2009a). It is crucial that all segments of the beef supply chain place the ut most importance on

PAGE 19

19 animal welfare due to the overwhelming media coverage of these cases and negative ramifications it has on the meat industry. Animal Handling Animal handling has a large impact on livestock stress. T here are multiple opportunities for an imals to be exposed to stress d uring the process of transportation from the farm to their ul timate destination Humans should handle livestock to limit anxiety responses that can cause negative physiological outcomes Handling responses can be most notably recognized through behavioral reactions (Broom, 2000). Cattle exposed to a new object s u ch as a trailer or handling facility will balk and/ or give vocaliz ed responses to the strange object (Grandin, 1997). However, as familiarity increases, livestock will become more cooperative with entering a new area (Peischel et al., 1980; as cited in G randin, 1997). Stress responses can be objectively measured by evaluating metabolic rate such as heart rate, blood pressure, respirat ion rate, and body temperature; plasma cortisol (Table 2 1); and adrenal medullary hormones, such as epinephrin e and nore pinephrine (Broom, 2000). Handling effects are compounded when animals are exposed to human handling techniques that elicit pain. Abusive practices by humans will be recollected by animals and can cause similar and exaggerated behavioral and physiologica l responses to general handling stressors (Grandin, 1997). Animals recollect negative experiences, and research has shown that calves have recognition of people they have had positive or negative interactions with (de Passille e t al., 1996; as cited by Go nyou, 2000). The use of paddles, prods, whips, and hot shots a re commonly found in livestock production facilities (NCBA, 2007) and are often times necessary to provoke efficient movement of livestock. However, it is the manner in which these tools are used that

PAGE 20

20 dictates the animal reaction. In the 2007 Non fed Beef Quality Audit (NCBA, 2007), 22.3% of all loads of cattle received applied the use of a hot shot to aid movement at the packing plant. Most plants (86.4%) reported using driving aids other t han hot shots in a passive manner, however, 13.6% of plan ts reported using driving aids, including sticks, paddles, body parts, PVC pipe, metal pipe, whips, and a flash light; in an aggressive manner (NCBA, 2007). The aggressive use of driving devices wil l evoke a stress response and can compromise an imal welfare. Thus, it is of ut most importance that animal handlers minimize aggressive handling to preserve animal welfare. An animal which incurs a slip or fall during the process of loading or unloading wi ll become stressed and exacerbate responses for the remainder of the lot. Care should be taken to ensure secure footing for livestock, especially when encountering a ramp, landing, or turning area (Tarrant and Grandin, 2000). Transport stocking density a nd the surface of the trailer floor play a major role in animal balance and the number of times an anima l slips or falls because cattle tend to stand during transport (Tarrant and Grandin, 2000). It is recommended that mature cows are allowed approximatel y 0.25 to .030 m 2 per 100 kg of body weight during transport (AMI, 2005). Tarrant et al. (1992) reported low stocking density had fewer animal struggles and falls than high stocking densities. However, it was also shown that there were less load shifts w hen stocking density was high (Tarrant et al., 1992; as cited by Tarrant and Grandin, 2000). A high transport stocking density will tend to restrict animal movement in the trailer, but cattle which do fall will be at greater risk for injury and subsequent bruising, with little room to return to a standing position. Livestock tend

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21 to be more comfortable at l ower stocking densities; but their balance is affected by driving techniques (Tarrant and Grandin, 2000). Stress Physiology Physiological Indicators of S tress The innate interactions of animal biology make stress levels challenging to quantify in vivo The initial response to stress is indicated by the release of the catecholamines epinephrine or adrenaline released from the adr enal glands, and norep inephrine or noradrenaline, released from both the adrenal glands and sympathetic nerve endings (Knowles and Warris, 2000). In tur n, both hormones increase heart rate, blood pressure and the rate of glycogenolysis, thus raising plasma glucose levels shortl y after the initial stress reaction (Knowles and Warris, 2000). Yet, due to the relatively short half lives of these hormones, they are a useful, albeit inconsistent measure of animal stress (Knowles and Warris, 2000). The hypothalamic pituitary adrenal (HPA) axis is a complex system of integrated ( Selye, 1939). Catecholamine release stimulates the release of corticotrophic releasing factor (CRF) from the hypothalamus of the brain (Plotsky et al, 1989), adrenocoricotrophic hormone (ACTH) from the anterior pituitary of the brain (Dinan, 1996), and glucocorticoids from the adrenal cortex (Dinan, 1996). Of the glucocorticoids released, cortisol is of primary interest in mammali an species. Through increases in cortisol levels, it enhances the function of gluconeogenesis, increases proteolysis, and alters CRF and ACTH release through negative feedback (Dickson, 1970). Considering this response is heavily mediated through the brai n and has a longer half life than epinephrine and norepinephrine,

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22 prolonged s tress (Knowles and Warris, 2000; Table 2 1) The release and absorption of water is control led by release of antidiuretic hormone (ADH) from the posterior pituitary (Houpt, 1970). During dehydration, a change in the osmoconcentration of plasma stimulates ADH release causing urine volume to decrease in an effort to retain water (El Nouty et al., 1980). The fluid lost during dehydration is mostly from the extracellular fluid (Houpt, 1970). There is a shift from water in the cells to the extracellular fluid, which is then lost through urine, feces, respiratory gasses, and perspiration (Houpt, 197 0). Electrolytes are also lost from the extracellular fluid during water deprivation. Sodium (Na + ), potassium (K + ), chloride (Cl ), and bicarbonate (HCO 3 ) levels in the plasma, blood, and urine often increase during periods of dehydration (Houpt, 1970). Aldosterone is the primary hormone responsible for reabsorption of Na + and K + and is regulated by ACTH from the anterior pituitary (Houpt, 1970). Dehydrated animals tend to have lower levels of plasma aldosterone associated with increased urine sodium le vels (El Nouty et al., 1980). Packed cell volume (PCV) is a measure of the percentage of cells occupying the total blood volume, and is measured by evaluating the proportion of plasma to cellular constituents in a blood sample (Knowles and Warris, 2000). PCV is a simple measurement of dehydration and is often accompanied with measurements of plasma protein and plasma albumin levels to confirm the degree of dehydration (Knowles and Warris, 2000) (Table 2 1) An increase in PCV percentage is indicative of either decreased plasma volume or increased cellular components in the blood, and would thus indicate a more

PAGE 23

23 dehydrated state (Kent and Ewbank, 1983). There are multiple proteins which comprise total protein found in the plasma. These proteins include: albumins, globulins, fibrinogens, along with multiple other regulatory proteins (Smith and Hamlin, 1970). Plasma proteins serve primarily as transport proteins, as well as regulating osmotic pressure, clotting factors, and aid in immune response (Smith an d Hamlin, 1970). During periods of dehydration, acute stress, or energy deficiency, plasma protein concentrations tend to increase due to mobilization of proteins to utilize as an energy substrate, or a decrease in total plasma volume (Siebert and Macfarl ane, 1975) (Table 2 1). The loss of blood, urine, and muscle metabolites also are an indication of dehydration as sodium, potassium, chloride, and bicarbonate are all depleted during fasting or while being withheld from water (Schaefer et al., 1989). Thi s can be most + + K + ) (HCO 3 + Cl )] (Schaefer et al., 1990 ). Lower values are an indicator of more normal hydrati on levels (Schaefer et al., 1990 ). During normal muscle activity, glycogen is the main carbohydrate store for muscle energy. Glycogen is broken down by glycolysis in to two glucose molecules that can be utilized as energy in aerobic metabolism (Aberle et al., 2001). The glucose is broken down into two p yruvic acid molec ules which then enter the tric arboxylic acid cycle to produce a net 37 ATP for energy (Aberle et al., 2001). During anaerobic conditions, the byproduct of glycolysis is lactic acid. Lactic acid is then transported to the liver a nd rephosphorylated throug h the Cori cycle to glucose molecules through gluc oneogenesis (Martin and Vagelos, 1962 ). As the intensity of muscle activity builds, there is a tendency to shift to a greater anaerobic metabolism, thus the catabolism of

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24 glycogen causes a build up of lact ate as a byproduct of anaerobic activity in the muscle and blood stream (Knowles and Warris, 2000). Along with this, creatine phosphokinase (CPK) is utilized by muscle to make ATP available for contraction. During strenuous muscle activity, creatine kina se (CK) in the form of CK3 leaks from muscle cells and can be detected in the blood analysis (Knowles and Warris, 2000). As such, both lactate and CK are also commonly measured parameters to indicate muscle stress. Adipose tissue is catabolized through lipolysis. T he pancreatic hormone glucagon stimulates adipose mobilization d uring periods of low blood glucose (Allen, 1970). Adipose tissue is broken down to triglycerides, which are further catabolized into acetyl CoA through beta oxidation (Allen, 197 0). An acetyl CoA molecule th en undergoes oxidative phosphory lation to produce ATP for energy utilization (Allen, 1970). The mobilization of adipose tissue for energy can be detected in the form of free fatty acids (FFA) and ketone bodies in the blood. When triglycerides are mobilized, they are broken down into the glycerol and non esterified free fatty acid (NEFA) or FFA components (Knowles and Warris, 2000). The liver converts the FFA to ketone bodies in the liver, particularly beta OHB), which is utilized by the tissues (Knowles and Warris, 2000). Meat Quality Stress Indicators Stress events can affec t live animal physiology, which can cause meat quality aberrations. The live animal uses glycogen as a carbohydrate source of energy for muscle contraction and lactic acid is produced as a byproduct of glycogenolysis (Jensen, 1954). When an animal is exanguinated, the absence of oxygen in the blood causes a shift from aerobic to anaerobic metabolism (Aberle et al. 2001). Since the c irculatory system can no longer carry lactate to the liver to be re synthesized into

PAGE 25

25 glucose and glycogen, lactic acid begins to concentrate within the muscle and cause the postmortem pH decline (Aberle et al. 2001). The rate of acidification is primarily determined by the rate of muscle metabolism immediately before, during, a nd after slaughter (Aberle et al., 2001; Figure 2 1) A n animal which is exposed to prolonged chronic stress, will have in vivo glycogen depletion resulting in insufficient lactic a cid production, and ultimately elevated pH values (> 5.8; Hedrick et al., 1959). This beef will have increased water holding capacity, and a dark lean color due to increased light absorbency (Hedrick et al., 1959; Figure 2 2). E xtreme cases o f glycogen d epletion cause a dry, firm and dark (D (Figure 2 1). T he increased pH holds myoglobin, the primary protein responsible for muscle color, in the ferrous state which also causes a darker lean color (Lawrie, 1958) The surfac e of DFD meat appears very dry due to increased water holding capacity, caused by a pH higher than normal beef that is further from the isoelectric point, resulting in a more open protein lattice with more ability to bind water (Lister, 1988) When anima ls are exposed to acute stress immediately prior to harvest, glycogen is metabolized quickly while muscle temperature is high, causing rapid accumulation of lactate and its associated decline of muscle pH (Briskey, 1964). This rapid acidification of muscl e during early post mortem metabolism denatures the protein and results in pale, soft, and exudative (PSE) meat (Figure 2 1). This is a significant quality defect in species with faster metabolizing, more glycolytic muscle proteins than beef. Thus, PSE i s primarily a problem within the pork industry (Scanga et al., 2003 ), but also in turkeys (Barbut, 1993) and chickens (Barbut, 1997). In contrast to normal or DFD meat, PSE meat has less ability to bind water (Figure 2 2), causing greater surface moisture and

PAGE 26

26 denatured myofibrils resulting in greater surface light reflectance and a soft texture ( Briskey, 1964) Other factors contributing to the rate of pH decline include: in vivo temperature, chilling rate, and conditions at the onset of rigor mortis (Aber le et al., 2001). Considering the conversion of muscle to meat has a sizeable impact on water holding capacity, color, texture, and shelf life, determining muscle pH is of primary importance for quantifying fresh meat quality. Color can be quantified obje ctively using a Hunter or Minolta colorimeter. The majority of domestic research uses a colorimeter to evaluate black to white (lightness; L* value; range = 0 to 100), green to red ( redness; a* value; range = 60 to 60), and blue to yellow (yellown ess, b* value; range = 60 to 60; Hunter, 2006). O bjective color imetry is used extensively within the meat industry due to its association with other meat quality attributes and consumer retail acceptability (Kropf, 1980) L a and b scores are highly corre lated to musc le pH and physiological maturity in beef cattle (Page et al., 2001). Additionally, it is well established that color is the primary driver of fresh retail meat purchasing ( Faustman and Cassens 1990) and consumers prefer reflective, youthful, beef products (Jeremiah et al., 1972). Ultimate pH has a dramatic impact on fresh meat shelf life. Beef with a higher pH than normal has increased water holding capacity and thus allows for increased microbia l growth, odors, and surface discoloration (Ho od and Tarrent, 1981 ). Furthermore, DFD beef is associated with poor sensory attributes and is identified by increased instances of off flavors (Wulf et al., 2002). As such, d ark cutting beef has little appeal to the consumer. Naumann et al. (1957) dete rmined that consumers

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27 evaluate meat purchases based on visual appearance and palatability. When purchasing fresh meat from the retail case, consumers must rely on their visual appraisal to aid in purchasing decisions. Therefore, beef that exhibits the af orementioned quality defects will be consistently passed over by the consumer. Beef from cattle with an older chronological age will tend to have a darker color than young beef, regardless of stress. Beef from older animals has a higher concentration of m yoglobin, which are the proteins responsible for muscle color (Aberle et al., 2001). Beef from older cattle is also characterized as tougher, with higher Warner Bratzler shear force (WBSF), as there is a strengthening of connective structures within the m uscle (Aberle et al., 2001). There is little change in the concentration of connective tissue within the muscle, however collagen and elastin cross links increase, which reduce the solubility of the fibers (Aberle et al., 2001). Berry et al. (1974) repor ted steaks from carcasses B maturity and younger to have significantly less connective tissue scores by a trained sensory panel than from C maturity or older carcasses, as well as more desirable overall palatability. Breidenstein et al. (1968) also report ed that steaks from E maturity carcasses had higher shear force values than those from A and B maturity carcasses. Values for meat quality properties of beef from aged cattle are indicated in Table 2 2. Livestock Marketing and Stress Attenuation Stress Du ring the Pre Slaughter Period Livestock are subject to numerous stressors. However, the pre slaughter period, including transportation and lairage, might be as stressful an experience as any in production. T he specific effects of transportation itself h ave been poorly defined;

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28 however, the l iterature suggests that when transport ation and lairage is combined with fasting and elimin ation of water availability, it exacerbates stress effects (Jones, 1988). During transportation animals can often be withdr awn f rom feed for hours at a time. According to the 2007 NFBQA (NCBA, 2007), all loads of non fed cattle traveled an average of 5.9 h and 454.6 km. With tractor trailer loads, these values increased to 8.6 h and 658.5 km respectively (NCBA, 2007). Typic ally these cattle are withheld from water during transport, and withheld from feed after leaving the farm, unless spending more than 24 h prior to being slaughtered at the packing f acility. Jones et al. (1988) reported that steers and heifers fasted 24 or 48 h and transported 320 km tended to have greater live weight losses and lighter carcasses than those fasted 24 h with no transport. Similar results have been found in a follow up b y Jones et al. (1990) reporting increased weight loss with an increase in fasting time. These significant weight losses affect both producers and packers by reducing carcass weight and red meat yield. Also, literature has shown that increased time off feed causes increased cooler shrink (Jones et al., 1988; 1990). Additional ly, less desirable hide dryness scores and increased difficulty of separating the hide form subcutaneous fat were observed by Jones et al. (1990). Both of these findings indicate that dehydration was the leading culprit for weight losses. Any stressor ca n increase metabolic rate, and since transported livestock have been withdrawn from feed, a negative energy balance can occur. T he negative energy balance of the animal gives precedent for livestock to mobilize body tissues to utilize as energy (Moe et al ., 1971) This can be detected through the release of metabolites in the blood and urine during and after times of prolonged stress exposure. Most notable

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29 are increases in urine osmolarity, which suggest increases in blood metabolites released in the uri ne and is an additional measure of dehydration (Schaefer et al. 1990). Studies done by Ru ppanner et al. (1978) have reported shifts in sodium, potassium and othe r fluid levels a s a competent indicator of stress in feedlot cattle, as well as decreased sal iva sodium concentrations (Post, 1965) and decreased potassium within the perspiration of fasted, transported dairy cattle (Schaefer et al., 1990). In a review by Knowles and Warris (2000), slaughter cattle have exhibited increases in FFA, OHB plasma p rotein, serum albumin, PCV, CK, and lactate, decreased glucose, and altered blood urea nitrogen concentrations compared with control cattle (Kno wles and Warris, 2000). Jones et al. (1988) reported carcasses from fasted and transported animals had a highe r proportion of bone to lean and fat compared to carcasses from control animals. This would be attributed to a chronic stress response affecting protein and adipose catabolism. Meat quality also suffers when animals are exposed to prolonged stress Studi es have shown that bulls subject to increased transport stress have higher postmortem pH at 45 min, and 24 and 48 h postmortem (Schaefer et al., 1990). These bulls also tended to have darker (lower L* value) and less red (lower a* values) lean color a nd less drip loss due to a higher postmortem pH (Schaefer et al., 1990). Schaefer et al. (2006) suggested that by decreasing stress by using an intervention, it is possible to decrease instances of dark cutting beef. Attenuation of Transport and Handling Str ess Livestock will experience a stress response during the normal activities a ssociated with marketing The magnitude of the effects of stress during marketing has an impact on economically important traits making it a valued research topic There

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30 have been numerous studies using various methods to mitigate transport and handling stress in young calves and finishi ng cattle, but very little evaluating cull cows (Hutcheson et al., 1984; Cole and Hutcheson, 1985; Schaefer et al., 1990; Gortel et al., 1992; Schaefer et al., 1992) The two interventions most commonly researched have been the use of electrolyte supplementation and pre slaughter conditioning prior to transport (Fike and Spire, 2006). Electrolyte supplementation has the ability to replenish bl ood metabolites and return acid base balance in the body to more acceptable levels (Schaefer et al., 1997) Typically, most electrolyte solutions are comprised of a carbohydrate source such as glucose, dextrose or sucrose; a bicarbonate derivative such as sodium bic arbonate or potassium bicarbonate; an agent to aid in water absorption such as sod ium chloride or magnesium sulfate; as well as other additives to restore body metabolites and balance ion and electrolyte charges. Research has shown that elec trolyte supplementation is successful at decreasing body weight loss during transport and improving hot carcass weight and carcass yield (Schaefer et al ., 1990; Gortel et al., 1992 ; Schaefer et al., 2006). Gortel at al. (1992 ) observed that crossbred bull s given electrolyte during lairage tended to exhibit better recovery from transport stress by having lower live weight decreases during lairage and had heavier hot carcass weights and greater carcass yields than non supplemented bulls. Gortel et al. (1992 ) reported that the increase in hot carcass weight and carcass yield was attributed to great intracellular fluid retention by treated bulls In the same study, bulls that were supplemented electrolyte tended to lose more live weight than bulls supplemente d with only water (Gortel et al., 1992). However, electrolyte treated bulls had greater hot carcass weights and carcass yields

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31 than water treated bulls (Gortel et al., 1992) Gortel et al. (1992) suggested that this could be attributed to electrolyte trea blood, pluck, and hide, but retaining more carcass tissue than control bulls. N umerous other studies have reported similar effects on carcass yield and weight loss in bulls, steers, and heifers (Jaco bson et al., 1993; Schaefer et al., 1993; Scott et al., 1993) Electrolyte supplementation has been shown to have impact on meat quality through the restoration of acid base balance and replenishment of body metabolites. Schaefer et al. (1990) found that bulls supplemented with electrolyte tended to have lower serum Na + K + and Cl concentrations, as well as significantly lower urine Na + and K + concentrations and higher muscle Na + levels than control bulls These researchers reported bulls supplemented w ith electrolyte had lower, more normal initial pH, a lighter, more reflective color, and lower Warner Bratzler shear force values than control bulls (Schaefer et al., 1990). Electrolyte therapy of transported cattle also showed to decrease the instances o f dark cutters compared to cattle offered only water (Schaefer et al., 1997). The use of altering the feed regimen of livestock prior to transport has also been used to mitigate stress response. This intervention is u sed as supplemental energy pre transp ort to increase blood glucose to prevent mobilization of adipose and protein tissue during the pre slaughter period Cole and Hutcheson (1985) reported that calves offered a concentrate diet ad libitum prior to fasting lost more weight during deprivation, but regained weight quicker after 3 days of refeeding than those given a restricted feed regimen. It also showed that increased pre fasting feed intake offers a larger reserve of energy, water, and electrolytes in the body during deprivation, and thus al lows the

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32 animal to return to a their optimal level of intake more quickly after transport (Cole and Hutcheson, 1985). Research also shows that cattle fed a high energy pre slaughter conditioning supplement tend to have a greater carca ss yield, fewer insta nces of dark cutting beef a greater proportion of USDA Prime and Choice carcasses, and fewer USDA Select and No Roll carcasses (Schaefer et al., 1999; 2006). Also, considering the relation ship of dark cutting beef with increased stress, the use of pre sl aughter conditioning or electrolyte utilization can markedly improve indicators of stress and welfare (Schaefer et al., 2006). Specific diet constituents can also be identified to improve certain other responses. Supplementation of specific amino acid s c an improve meat quality as physiological regulators of stress, substrates for amino acid metabolism, or substrates for gluconeogenesis (Schaefer et al., 2001). Tyrosine is a precursor for epinephrine, norepinephrine, and dopamine release, while tryptophan stimulates serotonin which stimulates sedation in mammals (Schaefer et al., 2001; Leathwood, 1987; as cited in Schaefer et al., 2001). Amino acid supplementation (alanine, glutamine, and glycine) is also shown to provide a source for gluconeogenesis as a n energy substrate during times of low nutrient status (Schaefer et al., 2001). However, given the complexities of nutrient, energy, protein, and ion depletion, single nutrient supplementation will often not address the entirety of the stress response. S chaefer (1995) found that the use of vitamin, mineral, and amino acid complexes were more effective in improving meat quality rather than a single nutrient alone.

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33 T able 2 1. Physi o logical assessment of stress in transported cattle Variable Value Source Basal packed cell volume, % 33.8 Lane and Ca mpbell, 1969 34.0 Wohlt et al., 1984 Post transport/handling packed cell volume, % 51.3 Gortel et al., 1992 42.5 Parker et al., 2007 37.1 Tadich et al., 2004 Basal plasma protein concentration, g/100 mL 6.4 Parker et al., 2003 7.9 Knowles et al., 1999 Post transport/handling plasma pro tein concentration, g/100 mL 7.9 Parker et al., 2003 8.6 Knowles et al., 1999 Basal plasma cortisol concentration, ng/mL 9.4 Elvinger et al., 1992 9.0 Mitchell et al., 1988 2.0 Alam and Dobson, 1986 Post transport/handling plasma cortisol concentration, ng/mL 13.0 Lay et al., 1992 21.5 Knowles et al., 1999

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34 Table 2 2. Normal muscle quality characteristics of advanced maturity beef Variable Value Source Normal pH 5.5 5.7 Aberle et al,, 2001 Dry, Firm, Dark pH > 5.8 Aberle et al., 2001 Lightness (L*) 1,2 35.0 Cranwell et al., 1996 Redness (a*) 1,2 23.7 Cranwell et al., 1996 Yellowness (b*) 1,2 9.6 Cranwell et al., 1996 Drip Loss, % 3 1.3 1. 6 Davis et al., 1979 Warner Bratzler Shear Force, kg 4.9 Cranwell et al., 1996 2,4 7.5 Davis et al., 1979 5 1 L* = measure of darkness to lightness (larger value indicates a lighter color); a* = measure of redness (larger value indicates a redder color); b* = measure of yellowness (larger value indicates more yellow color) 2 Data from cattle with mean skeletal maturity = E 33 and lean maturity = B 0 5 3 Data from C maturity cattle with average USDA quality grade = Commercial 4 Cows received feed last 56 d prior to harvest 5 Random sampling from C maturity carcasses from six U.S. packing plants.

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35 Figure 2 1. The relationship of postmortem pH decline with characteristics of beef muscle, adapted from Aberle (2001) Figure 2 2 The relationsh ip of beef muscle pH to water holding capacity, adapted from Wismer Pedersen (1987)

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36 CHAPTER 3 EFFECT OF ON FARM EL ECTROLYTE SUPPLEMENT ATION ON WEIGHT LOSS HYDRATION, STRESS, A ND MUSCLE QUALITY Materials and Methods Animals and Managemen t Experiment and data sampling on farm Sixty culled, lactating dairy cows were used for this study, which was conducted over 4 d in mid August, 2009. Ambient temperature ranged from 22 to 32C, with an average relative humidity of 75% for the live animal portions of the study. Cows ranged from 17 to 989 days in lactation. Cows were housed in an open sided free stall barn with concrete flooring with fans and misters for cooling. Test animals originated from two separate locations (Farm 5 and 8) of a 10,00 0 cow commercial dairy farm in Okeechobee County, Florida (27 three times daily, and were fed a total mixed ration ad libitum. Cows were milked for the final time 18 h prior to the start of the study. Following milking, farm management at both locations selected and sorted cull cows from the lactating herd for use on the trial. Cows were selected based on low milk production, reproductive inefficiency, and lameness. Cows f rom farm 8 (n = 30) were loaded by farm personnel on to 8.5 x 2.13 m livestock trailers at a stocking density of 509 kg/m 2 and transported 10 min. Cows were unloaded, comingled with cows from farm 5 and allowed to rest within the unused free stall barn wi th ad libitum access to feed. Cows were allowed access to water for the entirety of the trial, except while being transported.

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37 At 12 h prior to initiation of the trial, cows were withheld from feed, moved 100 m to a livestock working area, and processed t hrough a commercial squeeze chute to determine initial weight, then moved back to the vacant barn. Breed type (Holstein; Holstein x Jersey) and structural soundness were subjectively evaluated (Scale = 1 to 5; 1 = severe mobility issues; 5 = sound). Cows were randomly placed into two different holding pens for the duration of the on farm portion of the study. Initial weight, days in lactation, and farm of origin was used to stratify cows into two treatment groups; control (CON) or on farm electrolyte sup plemented (PRE). At 0500 h on day 1 of the study, all cows were secured in a squeeze chute, ear tagged, and blood sampled via coccygeal veinipuncture. Blood samples were collected in 10 mL BD Vacutainer tubes (BD Medical Supplies, Franklin Lakes, NJ) cont aining lithium heparin as an anti coagulant. A portion of the chilled blood sample was immediately placed into two 70 L capillary tubes and centrifuged at 1500 rpm for 15 min. The percent solids versus plasma in the capillary tubes was then measured us ing a Micro capillary Reader (Damon/IEC Division, Needham Heights, MA) and averaged between the two samples to determine packed cell volume (PCV; Bull et al., 2000). The remaining blood samples were placed on ice and after approximately 30 min, were centr ifuged at 1500 rpm for 15 min. Following centrifugation, two plasma samples were harvested into 1.5 mL micro centrifuge tubes and placed on dry ice for immediate freezing. Samples were transported to the University of Florida laboratory and stored at 20 C until utilized for analysis. Cows (PRE; n = 30) were orally drenched with an electrolyte solution using a 1000 mL drenching gun. A dry electrolyte powder consisting of dextrose, sodium

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38 bicarbonate, magnesium sulfate, and potassium chloride was dilute d in 1.5 L of water and was administered at a level of 2.4 g per kg of initial body weight (Table 3 1). Cows (CON; n = 30) were given a placebo volume of 1.5 L of water to simulate stress associated with drenching activity. Cows were moved to the livestoc k working area, and back to the vacant barn in two randomized groups (n = 30) with the first group being processed from 0500 to 0930 h and the second from 1000 to 1400 h. The area leading to and including the livestock working chute was shaded, but cows w ere not shaded following processing and prior to returning to the vacant barn. Transport, harvest, antemortem and postmortem data sampling At 1700 h on day 1, cows (n = 60) were loaded randomly onto two (30 cows in each) 15.24 x 2.5 m pot belly trailers and transported 3 h to a commercial beef processing facility. Cows were unloaded and randomly placed into three well bedded holding pens with twenty cows in each and allowed 11 h lairage time with ad libitum access to water prior to harvest. At 0330 h on day 2 of the trial, cows were processed through a squeeze chute, weighed and blood samples collected as described earlier. Cattle were stunned and humanely harvested according to USDA FSIS accepted procedures. All carcass measurements were taken from the left carcass sides at 24 h postmortem. Fat thickness and LM area was measured at the 12 th and 13 th rib interface. Internal fat was removed by plant personnel on the kill floor, thus KPH percentage was assumed to be 2.5% for all carcasses. Fat thickness, LM area, KPH percentage and hot carcass weight was used to calculate USDA yield grade (USDA AMS, 1997). Skeletal maturity, lean color maturity, and marbling score were evaluated by trained

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39 University of Florida personnel. A 5 cm thick section of LM origi nating from the 13 th rib interface and inside round, cap off (NAMP 169A) was collected. Following a 30 min bloom time, objective lean color analysis ( L*, a*, and b* ) were collected from the anterior LM end of the removed section and from three measurements on the medial side of the SM using a Hunterlab Miniscan XE Plus (Hunter Laboratory, Reston, VA) with an illuminant setting of D65/10 calibrated to a black tile and white tile. Intramuscular pH was measured from the same location of respective muscles usi ng a portable self equilibrating pH meter (HI 99163, Hannah Instruments U.S.A., Woonsocket, RI) One 2.54 cm steak was cut from the anterior LM end of the removed section for Warner Bratzler shear force (WBSF) analysis, vacuum packaged, stored at 4 2 C for 14 d, and frozen at 40 C. From the remaining LM portion, a section of LM trimmed free of external fat (12.24 g 1.55) was removed for drip loss analysis. The LM samples were weigh ed, identified and placed in 50 g Whirl pak bags (Nasco Internationa l, Fort Atkinson, WI) and suspended at 4 2 C for 24 h. After 24 h, each sample was reweighed and drip loss was calculated by dividing the weight difference by initial weight x 100. Blood Plasma Analysis Plasma samples were thawed at room temperature for 30 min, and 100 L of plasma was utilized to analyze plasma protein (PP) concentration. Concentrations were measured using a temperature compensated hand held refractometer (Reichert, Inc., Depew, NY). Warner Bratzler Shear Force Frozen steaks were re moved, weighed, and thawed for 24 h at 4 2 C. Steaks were then cooked on Hamilton Beach HealthSmart indoor/outdoor grills (Hamilton

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40 Beach, Proctor Silex, Inc., Southern Pines, NC) that were preheated for 20 min. Steaks were turned once when an internal temperature of 35 C was achieved, and continued cooking until they reached an internal temperature of 71 C (AMSA, 1995). Internal temperatures were monitored using a copper constantan thermocouple (Omega Engineering Inc., Stamford, CT) placed in the geom etric center of each steak, and were recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc., Middleboro, MA). Steaks were then chilled for 24 h at 4 2 C. After steaks were allowed to tempter to room temperature, 6 cores, 1.27 cm in diameter were removed parallel to the longitudinal orientation of the muscle fibers. The cores were then sheared perpendicular to the longitudinal orientation of the muscle fibers, using an Instron Universal Testing machine, Model 1011 (Instron Corpor taion, Canton, MA) with a Warner Bratzler shear head at a cross head speed of 200 mm/min. Statistical Analysis All results were analyzed as a completely randomized design with individual cow as the experimental unit for all variables measured. The GLM pro cedure of Statistical Analysis System V. 9.2 (2008, SAS Inst. Inc., Cary, NC) was used to test the model. Farm of origin, soundness score, days in lactation, breed, and the numerical order at initial processing were used as covariates in the model. Least square means were calculated for main effect of electrolyte treatment, and separated statistically using pair wise t tests (P DIFF option of SAS) when a significant (P < 0.05) F test was detected. Results and Discussion Weight Loss and Hydration On farm el ectrolyte treatment did not affect absolute body weight loss ( P = 0.84) or weight loss percentage ( P = 0.35) during the pre slaughter period (Table 3 2).

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41 Shorthose and Wythes (1988) estimated that cattle lose approximately .75% of their body weight per da y when feed and water is restricted, and it can be expected that shrink will increase sevenfold during transport (Jones et al., 1988). In the present study, percent shrink was considerably greater in both groups than normal transport shrink. There are m u ltiple factors that could have influenced transport weight loss, such as water intake prior to transport, gastrointestinal emptying during transit and lairage, and water intake overnight prior to the second weight measurement (Phillips et al., 1985; Jones et al., 1988; Warris, 1990). There were 8 h between when cows were unloaded at the processing facility and when the second weight was taken. Therefore, cows were allowed ample time to regain a portion of the transport shrink over the 8 h period, which co uld alter weight loss results. Results for PCV as an indication of hydration are reported in Table 3 3. Lane and Campbell (1969) reported that normal PCV for lactating dairy cows is 33.8% when ambient temperature averaged 24.0 C, suggesting cows within th e current study had elevated, but near normal values when the trial began. The pre slaughter PCV values of PRE cows decreased from the initial values and tended ( P = 0.06) to differ from CON cows whose values increased (Table 3 3). This indicates that co ws receiving an electrolyte supplementation stayed more hydrated during transport. This is likely an effect of increased extracellular and intracellular water retention through the replenishment of sodium and potassium (Tasker, 1980). These cations play a major role in maintaining osmotic equilibrium amongst major fluid compartments, and are diminished when an animal undergoes prolonged stress through salivary, urinary and fecal excretion, and evaporative water loss through respiration. With increased wa ter

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42 retention and absorption, it restores plasma volume, which is reflected in a lower percent solids in the blood and a lower packed cell volume. Plasma Protein Concentration The PP concentration change did not differ ( P = 0.18) between PRE and CON cows (Table 3 4). However, the PRE cows had a numerically lower increase in the PP concentration change than CON cows. Initial PP concentrations were elevated for both PRE and CON cows compared to reports by Knowles et al. (1999) and Parker et al. (2003) who reported basal PP levels as 7.9 and 6.4 g/100 mL, respectively for lactating dairy cows, suggesting the stress of initial sampling. These are consistent with findings by Siebert and Macfarlane (1975) that cattle under stress from heat and dehydration will have higher PP concentrations due to either decreased plasma volume or mobilization of protein tissues. Carcass Traits Descriptive statistics of carcass traits by treatment are presented in Table 3 5. There was no effect of electrolyte supplementation on carcass characteristics ( P 0.32) with the exception of PRE cows having a lower lean color maturity score ( P = 0.02). Cows utilized for the study exhibited comparable carcass traits to dairy cow carcass characteristics reported in the 2007 National Mark et Cow and Bull Beef Quality Audit (NFBQA; NCBA, 2007). Carcasses from PRE cows tended ( P = 0.06) to have a lower LM pH than CON carcasses (Table 3 6). During normal muscle metabolism, glycogen is used as a substrate to be converted to lactic acid, thus causing a steady pH decline following harvest (Lister, 1988). Antemortem depletion of muscle glycogen will result in insufficient lactic acid production for normal pH decline postmortem. On farm electrolyte supplementation likely restored glycogen within the muscle resulting in lower

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43 LM pH. Beef with pH values exceeding 5.8 have greater water holding capacity and a darker color than normal beef, but is not defined as a classic dark cutter (pH > 6.0) (Hedrick et al., 1959; Lister, 1988; Immonen, et al., 2 000). The pH values for carcasses in this study were greater than 5.8, a substantially higher value for ultimate pH of normal beef tissue (Hedrick et al., 1959). The higher than normal pH values were possibly driven by the stress created by high ambient temperature during the study, handling cows multiple times during blood collection, weighing, and transportation. Longissimus muscle from PRE cows had a greater ( P = 0.04) drip loss percentage than like samples from CON cows (Table 3 6). Davis et al. (1 979) suggested normal drip loss for C maturity beef with a normal 24 h postmortem pH to be between 1.3 to 1.6%. Values in Table 3 6 show that LM from PRE cows had closer to normal drip loss values than CON cows due to an ultimate pH further from the isoel ectric point (Aberle et al., 2001). However, both groups had below normal drip loss percentages, likely due to a pH that was above normal. Hunter L*, a*, and b* values did not differ ( P 0.11) between treatments at traditional probability levels for both LM and SM (Table 3 6). However, PRE cows exhibited a trend of higher L* and a* values, exhibiting lighter and redder LM and SM than CON cows, suggesting a relationship to the lower, more normal pH exhibited by PRE cows. Literature suggests that culls co ws on feed have LM Hunter L*, a*, and b* values that range from approximately 35.0 to 36.0, 23.0 to 32.0, and 10.0 to 23.0, respectively (Cranwell et al., 1996; Patten et al., 2008). Values for LM in Table 3 6 indicate a darker, less red, more yellow colo r from both CON and PRE cows in the

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44 current study. The darker color can be attributed to the greater light absorbance associated with elevated postmortem pH. Warner Bratzler Shear Force Warner Bratzler shear force values were similar ( P = 0.23) between LM steaks fro m CON and PRE cows (Table 3 7 ). The measurements in the current study are indicative of average WBSF values from C maturity beef of 7.5 kg reported by Davis et al. (1979). However, Cranwell et al., (1996) documented D maturity cows on feed for 56 d had an average shear force 4.9 kg. This is more indicative of the cows utilized for the study as they have been fed a high energy total mixed ration throughout the lactation period. Shackelford et al. (1991) reported that the threshold to classify young force values recorded in the study were much higher than that of younger maturity beef (Davis et al., 1979). As chronological age increases collagen becomes les s soluble resulting in cooked meat toughness (Mitchell, et al., 1928). Steaks from PRE cows tended ( P = 0.07) to lose less weight during cooking than steaks from CON cows (Table 3 7 ). This was surprising considering steaks from PRE cows had a lower ulti mate pH and a greater drip loss percentage than steaks from CON cows. Implications On farm electrolyte supplementation has potential to attenuate pre slaughter dehydration of cull dairy cows. Cows receiving electrolyte supplementation prior to pre slaught er stressors showed a tendency to be more hydrated prior to slaughter. Treated cows also exhibited a lower postmortem pH, and had a more normal muscle water holding capacity. The environment animals were exposed to resulted in a very

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45 significant stressor All cattle in this study displayed greater transport shrink, increased dehydration, elevated postmortem pH, darker muscle color, and less desirable water holding capacity than what is expected for cattle during normal marketing conditions. However, it suggests that electrolyte supplementation, has the ability to mitigate a portion of the aforementioned effects. Decreasing transport shrink can translate to increased profits to the producer when cattle are marketed to the processor, and more acceptable m uscle quality will provide a more desirable product to the consumer. Table 3 1. Ingredients of electrolyte supplement Ingredient Percent Dextrose 94.8 Sodium Bicarbonate 2.7 Potassium Chloride 1.5 Magnesium Sulfate 1.0 Table 3 2. Effect of on farm electrolyte supplementation on pre slaughter body weight loss Treatment 1 Item CON PRE SEM 2 P Value Initial Weight, kg 654.7 636.0 19.2 0.51 Post Transport Weight, kg 593.3 573.7 17.8 0.43 Weight Change, kg 62.0 63.5 5.0 0.84 Weig ht loss, % 9.2 10.2 0.7 0.35 1 CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW 2 SE of the least squares mean.

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46 Table 3 3. Effect of on farm electrolyte supplementation on packed cell volume of whole blood during pre slaughter period Treatment 1 Item CON PRE SEM 2 P Value Initial PCV % 35.85 35.34 0.70 0.62 Pre slaughter PCV % 36.40 34.62 0.68 0.08 PCV Change 0.55 0.72 0.45 0.06 % Change 1.63 1.74 1.20 0.06 1 CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW 2 SE of the least squares mean. Table 3 4. Effect of on farm electrolyte supplementation on blood plasma protein concentrati on Treatment 1 Item C ON PRE P Value Initial plasma protein conc., g/100mL 8.93 0.13 8.95 0.13 0.92 Pre slaughter plasma protein conc., g/100mL 9.34 0.12 9.24 0.11 0.60 Concentration change, g/100mL 0.41 0.08 0 .2 4 0.0 8 0.17 1 CON; oral ly drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW Table 3 5. Carcass characteristics by treatment group Treatment 1 Item C ON PRE P Value 12 th rib fat, cm 0.50 0.08 0.49 0.08 0.93 LM area, cm 2 67.9 2.7 67.6 2.7 0.94 Hot carcass wt, kg 313.8 9.8 304 .3 9.8 0.51 Dress ing % 53.0 0.7 53.2 0.7 0.83 Calculated YG 2 2.8 0.1 2.7 0.1 0.64 Marbling 3 408 28 426 28 0.66 Lean Maturity 4 426 12 382 12 0.02 Skeletal Maturity 4 437 29 417 29 0.63 Overall Maturity 4 432 18 407 18 0.32 1 CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW 2 YG = Yield Grade; calculated using 2.5% KPH. 3 Marbling score units: 300 = slight 00 ; 500 = modest 00 4 Maturity score units: 200 = B 00 ; 500 = E 00

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47 Table 3 6. Effect of on farm electrolyte supplementation on LM and SM pH and objective color measurement s and LM drip loss Treatment 1 Item CON PRE SEM 2 P Value LM pH 5.91 5.81 0.04 0.06 SM pH 5.90 5.85 0.03 0.35 LM Drip Loss, % 0.61 1.26 0.21 0.04 LM Lightness (L*) 3 32.99 34.38 0.82 0.25 LM Redness (a*) 4 18.43 19.25 0.60 0.35 LM Yellowness (b *) 5 15.08 15.99 0.45 0.17 SM Lightness (L*) 3 28.32 29.80 0.78 0.19 SM Redness (a*) 4 20.40 21.95 0.66 0.11 SM Yellowness (b*) 5 15.78 17.25 0.63 0.11 1 CON; orally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW 2 SE of the least squares mean. 3 L* = measure of lightness to darkness (greater value indicates a lighter color) 4 a = measure of redness (greater value indicates redder color) 5 b* = measure of yellowness (greater value indicates more yellow color) Table 3 7. Effect of on farm electr olyte supplementation on Warner Bratzler shear force and cooking loss Treatment 1 Item CON PRE SEM 2 P Value WBSF, kg 6.36 7.02 0.37 0.23 Cook loss, % 24.24 22.47 0.66 0.07 1 CON; or ally drenched with 1.5 L of water. PRE; orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW 2 SE of the least squares mean.

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48 CHAPTER 4 EFFECT OF ON FARM AND POST TRANSPORT ELECTROLYT E SUPPLEMENTATION ON W EIGHT LOSS, HYD RATION, STRESS, AND MUSCLE QUALITY Materials and Methods Animals and Management Experiment and data sampling on farm Forty eight culled, lactating Holstein Friesian dairy cows were used for this study which was conducted over 4 d in mid December, 2009. Am bient temperature ranged from 12 to 17 C, with an average relative humidity of 87% for the live animal portion of the study. Cows ranged from 20 to 439 days in lactation. Cows were housed in an open sided free stall barn with concrete flooring with fans a nd misters for cooling. Test animals originated from a 6,400 cow commercial dairy operation in Gilchrist County, FL (29 base, were milked three times daily, and were fed a total mixed ration ad libitum. At 18 h prior to the start of the study, farm management selected and sorted cull cows from the lactating herd for use in the trial, then moved them 50 m to a large dirt holding pen adjacent to the livestock working area. Cows were culled based on low milk produ ction, reproductive inefficiency, and lameness. Cows were allowed ad libitum access to water for the entirety of the trial. At 12 h prior to treatment administration, cows were moved 50 m to a livestock working area, and processed through a commercial squ eeze chute to determine initial weight, then moved back to the vacant holding pen. Structural soundness score (Scale = 1 to 5; 1 = severe mobility issues; 5 = structurally sound) was objectively evaluated. Initial weight and days in milk was used to stra tify cows into three treatment groups;

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49 control (CON), on farm electrolyte supplemented (PRE), or post transport electrolyte supplemented (POST). At 05 00 h the following day cows were withheld from feed. Cows were moved 50 m to the working area where they were held in an uncovered working pen bedded with sand. Cows were moved in small groups into a covered, dirt floor working pen which was ventilated by fans. Cows were then secured in a commercial squeeze chute, ear tagged, and blood sampled via coccygea l veinipuncture. Blood samples were collected in 10 mL BD Vacutainer tubes (BD Medical Supplies, Franklin Lakes, NJ) containing lithium heparin as an anti coagulant. A portion of the chilled blood sample was immediately placed into two 70 L capillary tub es and centrifuged at 1500 rpm for 15 min. The percent solids versus plasma in the capillary tubes was then measured using a micro capillary reader (Damon/IEC Division, Needham Heights, MA) and averaged between the two samples to determine PCV (Bull et al ., 2000). The remaining blood samples were placed on ice, and after approximately 30 min, were centrifuged at 1500 rpm for 15 min. Following centrifugation, two plasma samples were harvested into 1.5 mL micro centrifuge tubers and placed on dry ice for i mmediate freezing. Samples were transported to the University of Florida laboratory and stored at 20 C until utilized for analysis. Cows (PRE; n = 16) were orally drenched with an electrolyte solution using a 1000 mL drenching gun. A dry electrolyte pow der consisting of dextrose, sodium bicarbonate, magnesium sulfate, and potassium chloride was diluted in 1.5 L of water and was administered at a level of 2.4 g per kg of body weight (Table 4 1). Cows (CON

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50 and POST; n = 16, respectively) were given a plac ebo volume of 1.5 L of water to simulate stress associated with drenching activity. After exiting the chute, cows were released into an uncovered holding pen bedded with sand, and were moved collectively back to the vacant dirt lot at 0930 h, after all cow s were processed. Transport and plant electrolyte treatment At 14 00 h cows (n = 30) were loaded randomly onto a 15.24 x 2.5 m pot belly trailer, and the remaining cows (n = 16) were loaded onto an 8.5 x 2.13 m livestock trailer at 574 kg/m 2 Care was t aken by farm management to load cows with soundness issues in the rear compartment of the pot belly trailer to prevent further injury, as well as isolate lighter weight cows on the livestock trailer for ease of transport. Two cows in the POST group were r etained by farm management and not utilized for the remainder of the study. The cows were transported 2 h to a commercial beef processing facility Cows were unloaded and randomly placed in two holding pens (n = 23 per pen). At 1700 h cows were processed through a squeeze chute, weighed, and blood samples collected as described earlier. Cows (POST; n = 14) were administered an electrolyte treatment using the previously described procedure, with CON and PRE cows given a placebo volume of 1.5 L of water si mulate drenching associated stress. Lairage, harvest, and postmortem sampling Cows were allowed 8 h lairage time following post transportation sampling. At 0400 h the following day, cows were processed through a squeeze chute, weighed, and blood samples w ere collected as described earlier. At 1000 h, cattle were stunned and humanely slaughtered according to USDA procedures.

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51 Longissimus muscle pH was measured at 3 h postmortem and all other carcass measurements were taken from the same side at 24 h postm ortem. Fat thickness and LM area was measured at the 12 th and 13 th rib interface. Internal fat was removed by plant personnel on the kill floor, thus KPH percentage was assumed to be 2.5% for all carcasses. Fat thickness, LM area, KPH percentage and hot carcass weight was used to calculate USDA yield grade (USDA AMS, 1997). Skeletal maturity, lean color maturity, and marbling score were evaluated by trained University of Florida personnel. A 5 cm thick section of LM originating from the 13 th rib interf ace and inside round, cap off (NAMP 169A) was collected Following a 30 min bloom time, objective lean color analysis (L*, a*, and b*) were collected from the anterior LM end and from three measurements on the medial side of the SM using a Hunterlab Minisc an XE Plus (Hunter Laboratory, Reston, VA) with an illuminant setting of D65/10 calibrated to a black tile and white tile. Intramuscular pH was measured from the same location of respective muscle using a portable self equilibrating pH meter (HI 99163, Ha nnah Instruments U.S.A., Woonsocket, RI). During fabrication a 5 cm thick portion of the LM was removed, from which a 2.5 cm thick steak was cut for Warner Bratzler shear force (WBSF) analysis. From the remaining LM portion, a section of LM trimmed of e xternal fat (12.24 g 1.55) was removed for drip loss analysis. The LM samples were weighed, recorded and placed in 50 g Whirl pak bags (Nasco International, Fort Atkinson, WI) with corresponding identifications in 4 2 C for 24 h. After 24 h, each sa mple was reweighed and drip loss was calculated by dividing the weight difference by initial weight x 100.

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52 Blood Analysis Plasma samples were thawed at room temperature for 30 min, and 25 L of plasma was used in a commercial EIA kit (Diagnostic Systems La boratory, Webster, TX) to determine plasma cortisol concentrations. An additional 100 L of plasma was utilized to analyze PP concentration. Concentrations were measured using a temperature compensated hand held refractometer (Reichert, Inc., Depew, NY). Warner Bratzler Shear Force Shear steaks were vacuum packaged and aged for 14 d at 4 2 C and then frozen at 40 C. Frozen steaks were removed, weighed, and thawed for 24 h at 4 2 C. Steaks were then cooked on Hamilton Beach HealthSmart indoor/outdoo r grills (Hamilton Beach, Proctor Silex, Inc., Southern Pines, NC) that were preheated for 20 min. Steaks were turned once when an internal temperature of 35 C was achieved, and continued cooking until they reached an internal temperature of 71 C (AMSA, 1 995). Internal temperatures were monitored using a copper constantan thermocouple (Omega Engineering Inc., Stamford, CT) placed in the geometric center of each steak, and were recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc., Middleboro, MA). Steaks were then chilled for 24 h at 4 2 C. After chill, 6 cores, 1.27 cm in diameter were removed parallel to the longitudinal orientation of the muscle fibers. The cores were then sheared perpendicular to the longitudinal orientati on of the muscle fibers, using an Instron Universal Testing machine, Model 3343 (Instron Corportaion, Canton, MA) with a Warner Bratzler shear head at a cross head speed of 200 mm/min. Statistical Analysis All results were analyzed as a completely randomiz ed design with individual cow as the experimental unit for all variables measured. The GLM procedure of Statistical

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53 Analysis System V. 9.2 (2008, SAS Inst. Inc., Cary, NC) was used to test the model. Soundness score and days in lactation were used as cov ariates in the model. Orthogonal contrast to compare CON and POST treatments to PRE treatment for test. Least square means were calculated for the main effect of electrolyt e treatment, and separated statistically using pair wise t tests ( P DIFF option of SAS) when a significant ( P < 0.05) F test was detected. Results and Discussion Weight Loss and Hydration On farm electrolyte treatment tended to improve absolute weight loss ( P = 0.10) and weight loss percentage ( P = 0.06) during transportation for PRE cows compared to CON and POST cows (Table 4 2). There were no differences in weight loss ( P = 0.28) and weight loss percentage ( P = 0.46) during lairage between POST, CON and PRE cows. Cows receiving POST electrolyte supplementation reported a trend of lower actual weight loss and weight loss percentage than CON and PRE cows. Treatments did not differ for absolute weight loss ( P = 0.22) or weight loss percentage ( P = 0.42) ov er the duration of transport and lairage. However, CON cows had numerically greater weight change and percentage weight loss than electrolyte treated cows. These results are consistent with work done by Gortel et al. (1992) reporting improvements in weig ht loss in beef bulls given electrolyte therapy prior to transport. Gortel et al. (1992) attributed the lowered weight loss to the additional extracellular fluid volume found in treated bulls in their study. It is anticipated that the sodium and potassiu m supplementation increases cellular osmolarity, allowing for more fluid uptake and retention at the cellular level. It has also been reported that cattle supplemented with

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54 dietary sodium have increased water intake (Escobosa et al., 1984). Treated cows could have consumed more water following respective electrolyte treatments, which would have effects on rumen and gastrointestinal fill, as well as cellular water absorption. Cows from trial 2 had greater transport shrink compared to cows from trial 1. Th is was in large part attributed to when cows were removed from feed prior to initiation of the studies. Cows from trial 1 had a 12 h period in which feed was deprived, which likely resulted in a large portion of weight loss prior to starting the study, as compared to trial 2, in which cows had access to feed up until initial samples were taken. Thus, cows from trial 2 had more available weight to be lost via gastric emptying over the duration of the study. Cows from trial 1 likely excreted much of the ru men and gastrointestinal contents during the 12 h before the study began. Results for PCV as an indication of hydration are reported in table 4 3. The post transport PCV change for PRE cows did not differ ( P = 0.49) from CON and POST cows, although PRE co ws exhibited a trend of a lower numerical increase in PCV change than CON and POST groups. There were no statistical differences ( P = 0.22) in PCV change after lairage between POST cows and CON and PRE cows. However, POST cows exhibited a trend of decrea se d PCV change after lairage, while both CON and PRE groups showed a trend to increase. Over the duration of transport and lairage, there were no differences ( P = 0.29) in PCV change between treatments. Again, however, PRE and POST cows had lower increas es in PCV change than CON cows.

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55 Initial PCV percentage values of all cows in this study were substantially lower than those reported in Chapter 3 (Table 3 3). Additionally, the PCV of these cows was similar to the value of 33.8%reported by Lane and Campbe ll (1969) for lactating dairy cows in a thermoneutral environment. The difference in ambient temperature impacted the differences in initial PCV percentage value between the two trials. Cows from trial 2 also required less handling due to more appropriat e working facilities, were kept on dirt rather than concrete, and were exposed to fans during processing, compared with cows from trial 1; all of which could have impacted physiology. Plasma Protein and Cortisol Concentration Following transport, PRE cow s had a greater PP concentration increase ( P = 0.03) than CON and POST cows (Table 4 4). Following lairage, POST cows had a decrease in PP concentration change which differed ( P 0.01) from CON and PRE cows. Both CON and PRE treatments had an increase. Over the duration of transport and lairage, POST cows had a lower ( P PP concentration change than CON and PRE cows. All cows had initial PP concentrations similar to basal levels reported by Knowles et al. (1999) and Parker et al. (2003). Additio nally, cows in the current trial had markedly lower initial PP values than cows in Chapter 3 (Table 3 4), complimenting the results for PCV suggesting cows from trial 2 were subjected to a less stressful environment. Results from PP concentration change s uggest cull dairy cows should be supplemented after transport to the slaughter facility. During transportation, there was no difference ( P = 0.98) between PRE and CON and POST treatments in cortisol concentration change, however PRE cows tended ( P = 0.09) to have a higher initial plasma cortisol concentration prior to transport than CON and POST cows (Table 4 5). During lairage, there was no difference ( P = 0.13)

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56 between treatments in cortisol concentration, however POST and PRE cows appeared to have a tre nd of lower plasma cortisol concentration increases compared to CON cows (Table 4 5). Over the duration of transportation and lairage, cortisol concentration changes did not differ ( P = 0.58) between treatments, however, PRE and POST treated cows again ex hibited a trend of lower numerical cortisol concentration increases (Table 4 5). Cortisol concentrations were greater than reports for cortisol concentrations of lactating dairy cows reported by multiple authors (Lay et al., 1992; Knowles et al., 1999). T he findings for cows from this study to have normal PCV values but greater than normal PP concentrations are likely affected by the greater than normal plasma cortisol concentrations (Smith and Hamlin, 1970; Siebert and Macfarlane, 1975). Meat Quality Desc riptive statistics of carcass traits by treatment are presented in Table 4 6. There were no differences ( P 0.11) between treatments with carcass characteristics, with the exception of marbling score ( P = 0.03). However, results do not indicate that elec trolyte supplementation caused an improvement in marbling score. Cows utilized for the study exhibited comparable carcass traits to dairy cow carcass characteristics reported in the 2007 NFBQA (NCBA, 2007). Pre slaughter electrolyte supplementation did n ot affect ( P 0.27) LM or SM pH or objective lean color (Table 4 7). Longissimus samples from POST carcasses tended to have less drip loss ( P = 0.09) than CON and PRE carcasses (Table 4 7). Carcasses from trial 2 had markedly lower, more normal intramuscular pH valu es than those from trial 1, again suggesting a less stressful environment pre slaughter (Table 3 6). Also, the shortened feed withdrawal period for cows from trial 2 likely allowed for more availability of muscle glycogen, thus

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57 contributing to less variab ility in lean quality attributes. The similar pH values between treatments led to similar objective lean color values (Table 4 7; Page et al., 2001). Warner Bratzler Shear Force and Cooking Loss Pre slaughter electrolyte treatment did not effect WBSF valu es ( P = 0.87) or cooking loss ( P = 0.17) of LM steaks (Table 4 8). Longissimus muscle steaks from trial 2 had WBSF values that would be considered very tough (Shackelford et al., 1991). Implications Electrolyte supplementation had a greater effect on redu cing body weight shrink in the current study than trial 1. Pre slaughter electrolyte treatment improved the change in packed cell volume percentage and plasma protein concentration compared to control cows, suggesting supplemented cows were more hydrated and mobilized less tissue protein. Specifically, cows given post transport supplementation had better PCV and PP results than pre transport supplemented cows. Electrolyte treatment had no effect on any measurement of lean quality or carcass characteristi cs. All treatments exhibited normal muscle pH and water holding capacity. The differences in ambient temperature and handing stress between trial 1 and 2 likely had a major impact on weight loss and hydration variables, as well as ultimate intramuscular p H and water holding capacity between treatments. Consequently, it is expected that dietary electrolyte therapy is more efficacious when supplemented during periods of high heat stress, rather than more temperate environments. The results from this resear ch lead to the question, would electrolyte supplementation both pre and post transport have an additive effect on results? More research remains to be conducted on multiple supplementations for this to be proven. The current results suggest that pre sla ughter electrolyte treatment has the potential to

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58 reduce live weight loss during transportation and lairage when administered either prior to transportation or lairage. If weight loss is minimized in tissues associated with the hot carcass, there is poten tial for increased revenue to the producer when marketing cows to the processor on the rail. Table 4 1. Ingredients of electrolyte supplement Ingredient Percent Dextrose 94.8 Sodium Bicarbonate 2.7 Potassium Chloride 1.5 Magnesium Sulfate 1.0

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59 Table 4 2. Effect of pre and post transport electrolyte supplementation on weight loss during transport and lairage Treatment 1 P Values Item CON (n = 16) PRE (n = 16) POST (n = 14) CON + POST (n = 30) Treatment PRE vs. Others Ini tial weight, kg 726.0 27.6 730.3 33.8 0.90 Post transport weight, kg 671.4 23.0 670.3 23.0 628.6 25.0 650.0 28.6 0.38 0.48 Pre harvest weight, kg 2 642.4 22.9 639.5 22.9 624.2 24.9 0.85 Transport weight loss, kg 57.6 13.0 79.6 13.0 0.10 Transport shrink, % 8.58 1.99 12.45 1.99 0.06 Lairage weight loss, kg 3 28.9 12.0 30.8 12.0 4.5 13.1 0.28 Lairage shrink, % 4.41 1.96 4.98 1.96 1.52 2.12 0.46 Total weight change, kg 4 109.6 10.9 88.4 10.9 83.1 11.9 0.22 Total shrink, % 17.07 1.89 13.77 1.89 14.13 2.05 0.42 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1 .5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport. 2 Measured after 8 h lairage period, approximately 3 h prior to harvest 3 Weight loss over 8 h lairage period after second electrolyte or placebo supplementation was administered. 4 Weighloss from first electrolyte or placebo treatment to approximately 3 h prior to harvest.

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60 Table 4 3. Effect of pre and post transport ele ctrolyte supplementation on packed cell volume (PCV) Treatment 1 P Values Item CO N (n = 16) PRE (n = 16) POST (n = 14) CON + POST (n = 30) Treatment PRE vs. Others Initial PCV, % 32.38 0.91 32.35 1.12 0.97 Post transport PCV, % 33.83 0.83 33.09 0.83 32.90 0.90 33.37 1.03 0.72 0.79 Pre harves t PCV, % 2 34.72 0.78 33.73 0.78 32.54 0.84 0.18 Transport PCV change, % 0.60 0.52 0.96 0.52 0.49 Lairage PCV change, % 3 0.89 0.49 0.64 0.49 0.36 0.54 0.22 Total PCV change% 4 1.83 0.51 1.24 0.51 0.62 0.55 0.29 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1.5 L of water containing 2.4 g of dry electroly te per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electr olyte per kg BW after transport. 2 Measured after 8 h lairage period, approximately 3 h prior to harvest. 3 PCV change over 8 h lairage period after second electrolyte or placebo supplementation was administered. 4 PCV change from first electrolyte or plac ebo treatment, until approximately 3 h prior to harvest.

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61 Table 4 4. Effect of pre and post transport electrolyte supplementation on plasma protein (PP) concentration Treatment 1 P Value Item CON (n = 16) P RE (n = 16) POST (n = 14) CON + POST (n = 30) Treatment PRE vs. Others Initial plasma protein conc., g/100 mL 7.92 0.20 8.27 0.25 0.18 Post transport plasma protein conc., g/100 mL 8.39 0.20 8.53 0.20 9.07 0.22 8.73 0.25 0.07 0.43 Pre harvest plasma protein c onc., g/100 mL 8.54 0.22 8.70 0.22 8.81 0.23 0.69 Transport PP change, g/100 mL 2 0.61 0. 07 0.45 0.07 0.03 Lairage PP change, g/100 mL 3 0.15 0.08 a 0 17 0. 08 a 0 .2 6 0. 08 b < 0.01 Total PP change, g/100 mL 4 0 61 0. 0 8 a 0 78 0. 0 8 a 0 19 0. 0 9 b < 0.01 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport; POST, orally dren ched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport. 2 Measured after 8 h lairage period, approximately 3 h prior to harvest. 3 Change over 8 h lairage period after second electrolyte or placebo supplementation was admini stered. 4 Change from first electrolyte or placebo treatment, until approximately 3 h prior to harvest. a,b,c Within a row, values lacking a common superscript letter differ (P < 0.05).

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62 Table 4 5. Effect of pre and post transport electrolyte supplemen tation on plasma cortisol concentration Treatment 1 P Value Item CON (n = 16) P RE (n = 16) POST (n = 14) CON + POST (n = 30) Treatment PRE vs. Others Initial cortisol conc., g/d L 7.62 1.46 5.04 1.46 0.09 Post transport corti sol conc., g/d L 4.83 1.75 8.72 1.75 7.07 1.89 5.95 2.17 0.30 0.21 Pre harvest cortisol conc., g/d L 13.12 2.12 11.02 2.12 9.12 2.30 0.45 Transport cortisol change, g/d L 2 1.07 2.70 1.00 2.70 0.98 Lairage cortisol change, g/d L 3 8.29 2.34 2.31 2.34 2.06 2.54 0.13 Total cortisol change, g/d L 4 6.94 2.39 3.38 2.39 5.39 2.59 0.58 1 CON, orally drenched with 1.5 L of water pre and po st transport; PRE, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport. 2 Measured after 8 h lairage p eriod, approximately 3 h prior to harvest. 3 Change over 8 h lairage period after second electrolyte or placebo supplementation was administered. 4 Change from first electrolyte or placebo treatment, until approximately 3 h prior to harvest. a,b,c Within a row, values lacking a common superscript letter differ (P < 0.05).

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63 Table 4 6. Carcass characteristics by treatment group Treatment 1 Item Control PRE P OS T P Value 12 th rib fat, cm 0.27 0.07 0.30 0.07 0.13 0.07 0.22 LM area, cm 2 58.4 3.3 60.2 3.3 57.3 3.6 0.84 Hot carcass wt, kg 328.7 11.9 321.2 11.9 309.0 12.9 0.53 Dress % 51.1 1.1 50.1 1.1 49.8 1.2 0.65 Calculated YG 2 3.1 0.1 3.0 0.1 2.9 0.2 0.58 Marbling 3 392 39 459 39 302 42 0.03 Lean Maturity 4 427 2 6 438 26 490 28 0.23 Skeletal Maturity 4 414 38 418 38 516 41 0.14 Overall Maturity 4 418 30 430 30 506 32 0.11 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport. 2 YG = Yield Grade ; calculated using 2.5% average KPH 3 Marbling score units: 300 = slight 00 ; 500 = mode st 00 4 Maturity score units: 200 = B 00 ; 500 = E 00

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64 Table 4 7. Effect of pre and post transport electrolyte supplementation on pH and objective color measurements of the LM and semimembranosus and LM drip loss Treatment 1 Item CON PRE P OS T P Value 3 h postmortem LM pH 7.02 0.07 7.14 0.07 7.03 0.07 0.43 24 h postmortem LM pH 5.67 0.03 5.69 0.03 5.68 0.03 0.88 24 h postmortem SM pH 5.64 0.03 5.66 0.03 5.67 0.03 0.81 LM drip loss, % 1.79 0.27 1.20 0.27 0.91 0.30 0.09 L M Lightness (L*) 2 22.62 0.99 22.10 0.99 20.63 1.07 0.39 LM Redness (a*) 3 25.28 0.77 24.17 0.77 24.51 0.83 0.58 LM Yellowness (b*) 4 20.41 0.62 19.11 0.62 19.17 0.67 0.27 SM Lightness (L*) 2 20.42 1.30 19.95 1.30 21.48 1.41 0. 72 SM Redness (a*) 3 25.68 1.04 27.55 1.04 25.95 1.13 0.40 SM Yellowness (b*) 4 19.67 0.80 19.96 0.80 20.23 0.87 0.89 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1.5 L of water containing 2.4 g o f dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport. 2 L* = measure of darkness to lightness (greater va lue indicates a lighter color) 3 a* = measure of re dness (greater value indicates a redder color); 4 b* = measure of yellowness (greater value indicates more yellow color).

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65 Table 4 8. Effects of pre and post transport electrolyte supplementation on Warner Bratzler shear force and cook ing loss Treat ment 1 Item CON PRE P OS T P Value WBSF, kg 9.14 0.47 9.39 0.47 9.48 0.51 0.87 Cook ing loss, % 23.64 0.97 21.49 0.97 23.95 1.05 0.17 1 CON, orally drenched with 1.5 L of water pre and post transport; PRE, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW prior to transport; POST, orally drenched with 1.5 L of water containing 2.4 g of dry electrolyte per kg BW after transport.

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66 LIST OF REFERENCES Aberle, E.D., J.C. Forrest, D.E. Gerrard, E.W. Mills, H.B. Hen drick, M.D. Judge, and R.A. Merkel. 2001. Principles of Meat Science. 4 th Edition. Kendall/Hunt Publishing Company. Dubuque, Iowa. Alam, M.G.S., and H. Dobson. 198 6. Effect of various veterinary procedures on plasma concentr ations of cortisol, luteinizing hormone and prostaglandin E2 m etabolite in the cow. Vet. Rec. 118: 7 10 Animals. Eighth Ed. Edited by M.J. Swenson. Cornell University Press. Ithaca, New York. AMI (American Meat Institute) 2007. Recommended animal handling guidelines and audit guide, 2007 edition. http://www.animalhandling.org/ht/a/GetDocumentAction/i/1774 Accessed Nov. 15, 2009. AMSA (American Meat Science Association). 1995. Research Guidelines for Cookery, Sensory Evaluation, and Instrumental Tenderness Measurements of Fresh Meat. Am. Meat Sci. Assoc., Chicago, Il. Barbut, S. 1993. Colour measurements for evaluating the pale soft exudative (PSE) occurrence in turkey meat. Food Res. Int. 26:39 43. Barbut, S. 1997 Problem of pale soft exudative meat in broiler chickens. Br. Poult. Sci. 38:355 358. Berry, B.W., G.C. Smith, and Z.L. Carpenter. 1974. Beef carcass maturity indica tors and palatability attributes. J. Anim. Sci. 38: 507 514. Breidenstein, B.B., C.C. Cooper, R.G. Cassens, G. Evans, and R.W. Bray. 1968. Influence of marbling and maturity on the palatability of beef muscle. I. Chemical and organoleptic considerations. J. Anim. Sci. 27: 1532 1541. Briskey E. J. 1964. Etiological status and associated studies of pale, soft, exudative porcine musculature. Adv. in Food Res. 13: 89 178. Broom, D.M. 1991. Animal welfare: concepts and measurements. J. Anim. Sci. 69: 4167 41 75. Broom, D.M. 2000. Welfare assessment and welfare problem areas during handling and transport. Page 43 in: Livestock Handling and Transport. 2 nd Ed. Edited by T. Grandin. CABI Publishing. Wallingford, UK and New York, New York.

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67 Bull, B.S., J.A. Koepk e, E. Simson, and O.W. van Assendelft. 2000. Procedure for determining packed cell volume by the microhematocrit method; approved standard Third Edition. http://www.clsi.org/source/orders/f ree/h7 a3.pdf Accessed May 11, 2010. Cole, N.A. and D.P. Hutcheson. 1985. Influence of prefast feed intake on recovery from feed and water deprivation by beef steers. J Anim. Sci. 60: 772 780. Cranwell, C.D., J.A. Unrah, J.R. Brethour, and D.D. Simms. 1996. Influence of steroid implants and concentrate feeding on carcass and longissimus muscle sensory and collagen characteristics in cull beef cows. J. Anim. Sci. 74: 1777 1783. Davis, G.W., G.C. Smith, Z.L. Carpenter, T.R. Dutson, and H.R. Cross. 1979. Tenderness variations among beef steaks from carcasses of the same USDA quality grade. J. Anim. Sci. 49: 103 114. de Passille, A.M., J. Rushen, J. Ladewig, and C. Petherick. 1996. Dairy c discrimination of people based on previous handling. J. Ani m. Sci. 74: 969 974. Animals. Eighth Ed. Edited by M.J. Swenson. Cornell University Press. Ithaca, New York. Dinan, T. G. 1996. Serotonin and the regulation of the hypotha lamic pituitary adrenal axis function. Life Sci. 58: 1683 1694 Doumit, M.E., C.P. Allison, E.E. Helman, N.L. Berry, and M.J. Ritter. 2003. Biological basis for pale, soft, and exudative pork. Pages 9 15 in Proc. 56 th Am. Meat Sci. Assoc. Recip. Meat Conf. Columbia, Missouri. El Nouty, F.D., I.M. Elbanna, T.P. Davis, and H.D. Johnson. 1980. Aldosterone and ADH response to heat and dehydration in cattle. J. App. Phys. 48: No 2 249 255. Elvinger, F., P.N. Roger, P.J. Hansen. 1992. Interactions of heat stre ss and bovine somatotropin affecting physiology and immunology of lactating cows. J. Dairy Sci. 75: 449 462. Escobosa, A., C.E. Coppock, L.D. Rowe, Jr., W.L. Jenkins, and C.E. Gates. 1984. Effect of dietary sodium bicarbonate and calcium chloride on physi ological response of lactating dairy cows in hot weather. J. Dairy Sci. 67: 574 584. Faustman, C. and R.G. Cassens. 1990. The biochemical basis for discoloration in meat: a review. J. Musc. Foods. 1: 217 243. Fike, K. and M.F. Spire. 2006. Transportatio n of cattle. Vet. Clin. Food Anim. 22: 305 320.

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74 Wulf, D.M., R.S. Emne tt, J.M. Leheska, and S.J. Moeller. 2002. Relationships among glycolytic potential, dark cutting (dark, firm, and dry) beef, and cooked beef palatability. J. Anim. Sci. 80: 1895 1903.

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75 B IOGRAPHICAL SKETCH Travis Arp was born in Madison, Wisconsin in 1986, the son of Steve and Betty Arp. He was raised, along with his older sister and younger brother, on the University of Wisconsin Beef Cattle Research farm, which h is father managed. His family also owned and operated a small herd of purebred Gelbvie h and commercial cattle in north central Missouri. He graduated from Poynette High School, Poynette, Wisconsin in June 2004. While working on his undergraduate degree at the University of Missouri, he participated on the intercollegiate meat and livestoc k evaluation teams, and also worked at the University of Missouri Middlebush and South Farms, as well as the Bachelor of Science degree in agriculture economics in May 2008. He is currentl y a graduate assistant finishing a Mas ter of Science degree in the D epartment of Animal Science s at the University of Florida.