The relative significance of factors affecting and/or associated with slaughter, carcass and tenderness characteristics ...

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The relative significance of factors affecting and/or associated with slaughter, carcass and tenderness characteristics of beef
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viii, 117 leaves : ill. ; 28 cm.
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Alsmeyer, Richard Harvey, 1929-
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Thesis (Ph. D.)--University of Florida, 1960.
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Includes bibliographical references (leaves 110-117).
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by Richard Harvey Alsmeyer.
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Typescript.
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Vita.

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THE RELATIVE SIGNIFICANCE OF FACTORS

AFFECTING AND/OR ASSOCIATED WITH

SLAUGHTER, CARCASS AND TENDERNESS

CHARACTERISTICS OF BEEF









By
RICHARD HARVEY ALSMEYER









A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY








UNIVERSITY OF FLORIDA
June, 1960














ACKNOWLEDGMENTS


The writer wishes to express his deep appreciation to Dr. A. Zane

Palmer for his untiring efforts, guidance and assistance in the completion

of this study and preparation of this dissertation. Also very special

thanks and gratitude are given to Dr. Marvin Koger for his assistance and

direction in the statistical analyses of these data. He would also like

to thank Drs. D. S. Anthony, T. J. Cunha, W. G. Kirk and H. D. Wallace for

their kind administration and guidance.

Special thanks are directed to Dr. J. W. Carpenter, Mr. J. A.

Emerson, Mr. R. L. Gllbreath, Mr. 0. L. Huffman and Mr. J. L. Houle and

other fellow graduate students for their assistance in obtaining these

data.

The author wishes to express his sincere thanks to Mr. F. M.

Peacock, Dr. H. L. Chapman, Jr., W. C. Burns and other personnel at the

Range Cattle Station, Ona, the Everglades Experiment Station, Belle Glade,

the West Central Florida Experiment Station, Brooksville, and the Beef

Research Unit, Galnesville, for their help in caring for the animals and

assistance in collecting data for this study.

Sincere appreciation is expressed to my wife, Helen, for her help

and encouragement in the preparation of this dissertation.

The writer desires to thank Miss Charlotte Isbill for her untiring

patience and her accurate typing of this dissertation.





ii I














TABLE OF CONTENTS


Page
ACKNOWLEDGMENTS . .. .... i

LIST OF TABLES . . ... v

LIST OF FIGURES . . .. vilf

Chapter

I INTRODUCTION . . .

Need for Improvement in Beef Tenderness .. I
Trend Toward Meatiness in Beef. . 3
Slaughter and Carcass Characteristics . 5


II REVIEW OF LITERATURE . . 6

Beef Tenderness ................. 6
Slaughter and Carcass Characteristics of
Beef Cattle . 20
Cutability of the Beef Carcass. .. ....... 26


III EXPERIMENTAL . .... .. 30

Design and Animals Used . 30
Slaughter Procedures . . 31
Carcass Measurement Procedures. . .. 32
Carcass Cutting Procedures. . 33
Methodology for Measuring the Metacarpal and
Metatarsal Bones. . ... .33
Procedures Used In Obtaining Bone Breaking
Strength Measurements . 33
Method of Measuring Hide Thickness. . 34
Tenderness Sampling Technique . 34
Measurement of Longissimus Dorsi Area . 36
Tenderness Evaluation by Subjective and
Objective Methods . .... 36
Statistical Analysis. .. . .37











TABLE OF CONTENTS--Continued


Chapter Page

IV RESULTS AND DISCUSSION . .. 40

Beef Tenderness .. ..... ... 40
Meatiness of the Beef Carcass .. ....... 79
Effect of Percentage Brahman Breeding on
Slaughter and Carcass Characteristics of Beef 85


V SUMMARY AND CONCLUSIONS. . ... 103

LITERATURE CITED. . . . 110














LIST OF TABLES


Table Page

1 Sires and Percentages of Brahman Breeding of 538
Cattle Used in Determining the Relative Significance
of Factors Influencing Beef Tenderness .. 41

2 The Relationship of Outside Finish and Marbling
to Tenderness as Shown by Simple Correlations
and Simple and Partial Regression Coefficients ... 42

3 The Relationship of Conformation and Tenderness
as Shown by Simple Correlations and Simple and
Partial Regression Coefficients. . .. 45

4 The Relationship of Animal Age at Time of Slaughter
with Tenderness as Shown by Simple Correlations
and Simple and Partial Regression Coefficients ..... 47

5 The Relationship of Carcass Grade with Tenderness
as Shown by Simple Correlations and Simple and
Partial Regression Coefficients . 49

6 Effect of Breeds of Sire, Percentage Brahman
Breeding of Progeny and Location on Tenderness
Evaluations by Panel and Shear . .... .51

7 Average Tenderness Scores by Panel and Shear for
Angus, Brahman, Hereford and Shorthorn Sires 53

8 Relationship of Breed of Sire to Tenderness
Evaluated by Panel . ... 56

9 Effect of Percentage of Brahman Breeding of
Progeny on Average Tenderness Scores .. 59

10 Heritability Estimates for Tenderness by Panel
and Shear Based on Intraclass Correlation of
Offspring by the Same Sire .. 62

11 The Relative Significance of Factors Influencing
and/or Associated with Beef Tenderness . 64

12 The Effect of Percentage of Brahman Breeding on
Averages of Tenderness Scores and Average
Tenderness Scores by Panel Members and Shear Areas. 67











LIST OF TABLES--Continued
Table Page

13 Relationships Between Two Methods of Tenderness
Evaluation and Among Panel Members and Shear
Areas of the Longissimus Dorsi Muscle and
Their Relationship to Carcass Grade. . 69

14 Partial Regression Coefficients Showing the
Effects of Tenderness Panel Evaluations and
Carcass Grade on Tenderness Shear Score. ... 71

15 Simple Correlations Between Age, Hide Thickness
and Bone Breaking Strength . ... 74

16 Average Hide Thickness, Bone Breaking Strength
and Tenderness Evaluations by Breed Group. ... .. 75

17 The Relationship of Breeding and the Combined
Effects of Age, Hide Thickness and Bone Breaking
Strengths on Beef Tenderness . 76

18 Partial Regression Coefficients of Age, Hide
Thickness and Bone Breaking Strength on
Tenderness Evaluations . . 78

19 Average Physical Measurements of Metacarpal and
Metatarsal Bones Characteristics and Longissimus
Dorsi Area by Breed Group for 100 Animals. 80

20 The Relationship of Combined Effects of Bone
Characteristics and Carcass Size and the Effect
of Percentage of Brahman Breeding of Progeny
on Longissimus Dorsi Area. ... 82

21 Partial Regression Coefficients of Carcass Size,
Bone Characteristics and Percentage of Brahman
Breeding of Progeny and Carcass Muscling ..... .. .83

22 The Effect of Percentage of Brahman Breeding of
Progeny on Slaughter Characteristics of Beef 86

23 The Effect of Slaughter Weight, Carcass Weight
and Breeding on items Removed During the
Slaughter Operation. . .. .88

24 The Effect of Percentage of Brahman Breeding of
Progeny on Percentage of Head, Feet, Hide,
Gastro-intestinal Tract and Contents, Pluck and
Liver of 222 Cattle. .. . ... .. 89











LIST OF TABLES--Continued


Table Page

25 The Effect of Percentage of Brahman Breeding
of Progeny on Certain Carcass Characteristics
of 125 Cattle . . 92

26 The Effect of Brahman Breeding of Progeny on
Certain Carcass Characteristics with Carcass
Grade and One-half Carcass Weight Held
Constant. .. . .. 93

27 The Effect of Percentage of Brahman Breeding of
Progeny on the Wholesale Cutability of the Beef
Carcass . . . 96

28 Partial Regression Coefficients for Breed Effect,
Carcass Grade and One-half Carcass Weight on
Weights of Wholesale Cuts of the Beef
Carcass .. . . 100














LIST OF FIGURES


Figure Page

1 Location of Points at Which Hide Thickness
Was Measured ................... ... 35

2 Steak Sampling Procedure for Tenderness
Evaluation by Panel and Warner-Bratzler Shear. .. 38

3 Effect of Brahman Breeding of Sire on Tenderness
of Progeny as Evaluated by Tenderness Panel. 60


viii















CHAPTER I


INTRODUCTION


Need for Improvement in Beef Tenderness

Consumer preference studies conducted over the past few years at

various locations throughout the nation indicate that consumers are pri-

marily Interested in leanness and tenderness attributes of beef. Of the

palatability attributes of beef, tenderness is one of the most important.

The meat Industry has shown marked Interest In the problem of beef ten-

derness; research in this area has Increased very materially during the

past few years.

Factors such as finish, animal age at time of slaughter and

breeding have been studied, singly, to provide a better understanding of

beef tenderness. Numerous studies have centered around the relationship

between fatness or finish and tenderness. Black et al. (1940) and

Branaman et al. (1936) in earlier studies found little or no relationship

between finish and tenderness. In 1956, Cover et al. (1956) reported a

positive association between fatness and tenderness but the reported re-

lationship was not high. With broiled loin steaks, only 10 per cent of

the variability in beef tenderness was accounted for by variations In

fatness. Inasmuch as marbling of the rib eye is indicative of fat dis-

persion within lean tissue, other workers have studied the marbling-

tenderness relationship. Stouffer and Wellington (1957, 1959) found mar-

bling to be only moderately associated with tenderness of steaks.

I











Beef tenderness long has been thought to be negatively influenced

by animal age at time of slaughter; younger carcasses were considered

more tender than older carcasses. Hiner and Hanklns (1950) studied the

effect of animal age at time of slaughter. Fifty-two animals were used

which varied widely as to age; the study was summarized to the effect

that as animal age at time of kill increased, tenderness decreased. Sim-

ilar conclusions have been reported by Brady (1937), Dunsing (1959),

Helser (1929) and Mackintosh et al. (1936) in studies involving the age

and tenderness relationship.

Two studies have Indicated tenderness differences among certain

breeds and lines of cattle. Carpenter et al. (1955) reported that as

the percentage of Brahman breeding increased, the tenderness of steaks

and roasts decreased. Cartwright (1957) found more variability in ten-

derness among Brahman sire groups sampled than among the Hereford sire

groups. Thus, there appeared to be difference within and between certain

breeds of cattle in tenderness.

Although singular effects of finish and/or marbling, age at time

of slaughter and breeding are reported in the literature, little is known

of the relative significance of the major factors influencing and/or

associated with beef tenderness. The primary objective of this research

was to study the singular effects of finish or marbling, age at time of

slaughter and breeding on beef tenderness and to determine the relative

importance of these factors influencing or associated with beef

tenderness.












Trend Toward Meatiness in Beef

Consumer research has consistently shown that consumers demand

lean beef with a minimum of fat and bone. The retailer today, forced to

trim retail cuts of excess outside fat and bone to comply with consumer

demands, must increase lean cut prices to compensate for the excess fat

and bone removed and for labor costs of the trimming process. Yet, if

beef carcasses could be produced with greater amounts of muscling and

less waste fat and possibly less bone, retail cuts would require minimum

trimming.

In a study of 459 beef carcasses reported by Pierce (1959) it was

noted that yield of major wholesale cuts (round, loin, rib and chuck)

may vary by as much as 25 per cent from low to high yielding beef car-

cass or range from 45 to 70 per cent of the carcass weight. The study

indicated that variations in cutability, or yield of preferred cuts of

the carcass, were influenced primarily by conformation and fatness of

the carcass. Unfortunately, perhaps, conformation and fatness had oppo-

site effects on the retail yields of these cuts. Superior conformation

increased cutability while the addition of finish decreased it. Since

carcasses within grades tended to be more uniform In conformation than

in per cent trimmable fat, the finish of the carcass in a particular

grade had greater influence on cutability or yield than did conformation.

The yield of major retail cuts is usually lowest in the Prime grade and

increases as grade decreases.

The Influence of Brahman breeding was reported by Carpenter

(1959) to significantly increase the yields of loin end, round, rib and

shank and decrease yields of plate of carcasses of 67 cattle. These












differences in cutability were traced directly to percentage of Brahman

breeding even though finish and conformation were not considered.

It thus being established that differences in carcass yields do

exist, the development of an accurate means of objectively or subjec-

tively determining carcass yield becomes important.

In a study involving forty animals, Cahill et al. (1956) found a

direct relationship between the edible portion of the carcass and the

area of the Longlssimus dorsi muscle at the twelfth rib. The highly sig-

nificant correlation coefficient was .853 thus indicating the measurement

to be quite reliable in predicting carcass meatiness. Although accurate,

the measurement requires slaughter of the animal for the "rib eye" meas-

urement and thus progress could be made only on a progeny testing basis.

For this reason an accurate live animal evaluation would be useful.

McMeekan (1957) stated that a definite relationship between

weight of bone and muscle exists. He concluded that a wealth of fleshing

is not possible unless there is a heavy weight of bone. The shorter and

thicker the bone, the greater the depth and thickness of muscle over that

bone. Should these statements be confirmed it might be possible to esti-

mate muscular development by objective measurements of the metacarpal or

metatarsal bones of the live animal.

Further objectives of this study were to determine the Influence

of breeding on carcass yield of the higher priced cuts and to determine

the relationship between certain weights and measurements of the meta-

carpal and metatarsal bones and area of the Longissimus dorsi muscle.








5



Slaughter and Carcass Characteristics

In the southern regions of the United States Brahman cattle and

more recently Brahman X European breeds have become rather prominent.

Their popularity was based primarily on superior heat tolerance, adapta-

bility and to take advantage of the genetic phenomenon, heterosis. Sev-

eral studies have reported advantages for Brahman and Brahman crosses in

dressing percentage, weight of hide and gastro-intestinal tract and con-

tents. Differences in breeding which significantly affect such slaughter

characteristics of economic Importance should be more firmly established

to enable the packer buyer to know what should be expected of the cattle

purchased and to aid in arriving at a fair price for those cattle.

A purpose of this study Is to determine the effect of breeding on

dressing percentage, percentage hide and percentage gastro-intestinal

tract and contents. An additional objective of this study is to deter-

mine the effects of hide thickness and breaking strengths of metatarsal

and metacarpal bones on the tenderness of beef.














CHAPTER II


REVIEW OF LITERATURE


Beef Tenderness

The Relationship of Finish or Marbling and Tenderness

The concept that increased finish and marbling enhances beef ten-

derness has been supported widely by popular opinion and researchers for

many years. Armsby (1917) wrote, "The fattening of an animal is a prac-

tice based on experience, which has shown that the tenderness and palata-

bility of the meat are materially increased thereby, so that the consumer

is willing to pay a higher price for it." In 1908 the same author stated,

"Marbling of the meat, which adds to its tenderness and perhaps to its

flavor and digestibility when cooked, increases its nutritive value."

Statements by Bull (1937) and Morrison (1950) also proclaim beneficial

tenderness results due to increased finish and marbling. Mackintosh

et al. (1936) found marbling to significantly contribute to increased

tenderness of beef.

In a study Involving twenty-four, three-year-old steers, Black

et al. (1931) noted differences in tenderness which could be attributed

to differences in finish. Tenderness differences, though slight, were

less than might be expected. Studies by Barbella et al. (1939), Hankins

and Ellis (1939), Murphey et al. (1942) Wanderstock and Miller (1948),

Husaini et al. (1950), Batterman et al. (1952), Stouffer and Wellington

(1957, Kieffer et al. (1958), Simone et al. (1958) and Saffle and

6











Bratzler (1959) Indicate that the differences in tenderness accounted for

by fatness or marbling are very small and often Insignificant. Research

by Cover et al. (1956) Indicated that tenderness scores were more closely

correlated with ether extract than with other fatness measures In a study

of thirty-eight yearling steers. When loin steaks were cooked by broil-

ing, variations in fatness, at best, accounted for about 10 per cent of

the variation in tenderness as evaluated by panel. The correlation be-

tween degree of marbling and Warner-Bratzler shear score was -.22 which

was not significant. Therefore, even though there appeared to be a posi-

tive relationship between fatness and tenderness, the relationship was

not high.

Research at Missouri by Naumann (1956) showed a very low relation-

ship between marbling and tenderness of beef. In a study of seventy-two

cattle, Branaman et al. (1936) found no relationship between marbling or

fatness and tenderness; however, it was noted that flavor and Juiciness

tended to increase with Increased marbling. Black et al. (1940) reported

that tenderness was not significantly changed due to increased finish in

a study involving 129 animals, Husainl et al. (1950) found only insig-

nificant relationships between finish or marbling and tenderness. Thus,

it appears that marbling or finish has little value In predicting tender-

ness of beef.


The Relationship of Age at Time of Slaughter and Tenderness

It has been generally accepted that older animals lack the ten-

derness of younger animals. Helser (1929) states that reddish colored,

soft bones indicate youthfulness in beef carcasses and that such carcasses











provide meat that is more tender than carcasses with more mature bones as

generally found in older carcasses. More recently, Dunsing (1959) and

Simone et al. (1959) found that cattle finished at eighteen months of age

were more tender than those finished at thirty months. In an earlier

study at Kansas, Mackintosh et al. (1936) reported meat from mature steers

to be tougher than beef from yearling steers. Similar findings were re-

ported by Brady (1937) In a comparison between yearling steers and mature

Holstein cows. Hiner and Hankins (1949, 1950) studied the effect of anlr

mal age at time of slaughter, using fifty-two animals which varied widely

as to age, calves two and one-half and seven months of age, steers six-

teen months, heifers three years and cows five and one-half years of age.

The carcass grades were not comparable due to grade being affected by

age, but the study was summarized to the effect that as animal age at

time of slaughter increased, tenderness decreased.


The Relationship of Carcass Grade and Tenderness

Though the Federal carcass grade of beef Is the consumers best

guide to palatability today, some doubt has been raised as to the accu-

racy of this evaluation Insofar as beef tenderness is concerned. Renewed

Interest in the relationship between tenderness and carcass grade began

in 1937 when Cover (1937) noted that carcass grades of twenty-four steers,

ranging from Prime to the present day Utility, were not particularly re-

lated to the tenderness of the meat as evaluated by a trained tenderness

panel. The tenderness scores were widely scattered over the tenderness

scale which indicated that the meat from some carcasses in lower grades

was as tender as meat from carcasses in higher grades. The author states,












Apparently, tender meat was not limited to beef from the higher grade

carcasses," Even though certain conditions in the test were quite vari-

able, the data nevertheless aroused doubt and curiosity about this grade

and tenderness relationship.

A recent California study by Dunsing (1959) In which consumers

rated steaks of different grade for tenderness as well as other eating

characteristics indicated that steaks of the Choice grade were preferred

over those of the Good grade. It is interesting that selection on visual

appearance and palatability by the participants were in agreement only

about one-half the time, thus indicating that meat which appeared to be

tender, Juicy and tasty to the participant was not necessarily so by eat-

ing tests.

Trowbridge and Moffet (1932) noted a slight increase in tender-

ness for meat from carcasses of higher grade. Similar findings were re-

ported by Cole et al. (1957) whose data indicated that a trained taste

panel and household consumer testing showed a preference for meat from

the higher grades of beef. Blakeslee and Miller (1948) used six Choice

carcasses, six Good carcasses, three Commercial and three Utility car-

casses to test for differences in tenderness by the Warner-Bratzler shear

technique. The results showed a significant difference in tenderness in

favor of the higher carcass grades. In a study of nineteen steers test-

ing the effect of full feeding in drylot versus feeding corn on pasture,

Pearson and Miller (1949) found the steers fed in drylot to grade higher

and steaks from the carcasses more tender than the lower grading steers.

Wisconsin workers, Batterman et al. (1952) reported a significant Improve-

ment in tenderness of meat from Cutter cows that were later fed to the











Utility grade. The technique of sampling used was similar to that de-

scribed by Wilson et al. (1955). Paul and Bratzler (1955a, 1955b) re-

ported that meat from Prime carcasses was significantly more tender than

meat from carcasses of the Good and Commercial grades.

A California report, Simone et al. (1958), summarizing a three-

year study on forty-eight steers of the Hereford breed, states, "As re-

gards tenderness, the taste panel preferred meat from rounds and ribs of

carcasses grading Choice, twice as frequently as meat from carcasses

grading Standard." The correlations between grade, ether extract and

tenderness, Juiciness and flavor were relatively low and only the corre-

lation between flavor and ether extract was significant. Sleeth (1957)

reported tenderness values on twenty-four Good and twenty-two Choice car-

casses indicating no apparent differences in tenderness between the two

grades.

An Oklahoma report by Kieffer et al. (1958) Indicated little re-

lationship between carcass grade and tenderness as measured by Warner-

Bratzler shear since both correlations on an intra-sire and total basis

were .00. Similar findings were reported by Texas workers, Cover at al.

(1958).

It seems that carcass grade bears a limited relationship in ten-

derness, but in most studies carcass grade was only slightly effective in

predicting tenderness and in two reports there was no relationship at

all. Therefore, researchers must turn elsewhere for a more reliable

indicator of beef tenderness.











Effects of Breeding on Beef Tenderness

Many differences in cattle can be traced to breeding and breeds.

These differences are often of economic importance and must be taken into

account in conducting research studies with cattle. The earliest report

associating tenderness differences with breeding was published by Black

et al. (1934). The report noted that meat from Brahman crossbred cattle

was significantly less tender than meat from Hereford and Shorthorn

cattle. Later research by Yao and Hiner (1953) showed tenderness to be

30.3 per cent heritable among 298 beef and dual-purpose Shorthorn steers

and a heritability of 76.6 per cent with the Warner-Bratzler shear score.

It is Interesting that the heritability for palatability was much higher

among dual-purpose Shorthorns than among the beef type; however, shear

score heritabilitles were 93.8 and 52.0 per cent, respectively, for beef

type and dual-purpose Shorthorns. These coefficients of heritability

indicate that progress through breeding for tenderness could be moderately

effective.

A comparison of various percentages of Brahman and Shorthorn

breeding by Carpenter (1955) suggested a decrease in tenderness with an

increase in percentage of Brahman breeding. Additional evidence indicat-

ing Brahman cattle to be less tender was presented by Cartwright (1957)

who states, "There was more variability among the Brahman sire groups

sampled than among the Hereford sire groups. Progeny of some Brahman

sires equaled or excelled in tenderness those of some Hereford sires, but

this was not true for all Brahman sires." In the Cartwrlght (1957) study,

Brahman progeny were less tender than Hereford progeny with the cattle of

Brahman and Hereford breeding being generally intermediate. Due to the











greater variability among the Brahman sire groups, progress in tenderness

breeding could be more rapid within the Brahman breed than within the

Hereford.

Kincaid (1957),summarizing studies involving different breeds of

cattle, states that a decrease in carcass grade was noted among Brahman

cattle and animals with a high percentage of Brahman breeding when com-

pared with cattle of European breeding. The author also found a decrease

in tenderness of meat with increases in the proportion of Brahman breed-

ing. In research Involving forty-nine progeny by five Hereford and six

Brahman sires, Cartwrlght et al. (1957), finding significant differences

due to breed of sire and also sires within breeds, stated, "Work contin-

ues to indicate that heritablllty of certain eating quality characters

may be of a magnitude to allow effective selection. There was again more

variability among the Brahman sire groups than among the Hereford sire

groups."

Work at the Louisiana Station by Damon (1957) showed the follow-

ing average tenderness scores as measured by Warner-Bratzler shear:

Angus crosses, 11.0; Brahman crosses, 15.0; Brangus crosses, 11.2;

Charolaise crosses, 10.3; Hereford crosses, 11.6; Shorthorn crosses, 11.8.

These data indicate that Brahman crosses are significantly less tender

than cattle of other breeds. In a Florida study involving steers of

Angus, Hereford, Brangus, Santa Gertrudis and Brahman breeding, Burns

et al. (1958) found a highly significant difference in carcass grade and

a significant difference in tenderness between Angus and Hereford and

Brahman steers. Animals of British breeding were more tender than Brahman

while the Brahman cross breeds were Intermediate in tenderness. Similar











findings were reported by Cole et al. (1958) in a study involving Angus,

Hereford, Jersey, Guernsey, Brahman and Brahman crossbred steers which

indicated that British breeds were significantly more tender than Brahman

and Brahman crosses with the dairy breeds having shear test ratings In-

termediate between these two groups. Warwick (1958) noted tenderness

differences between two breeds of beef cattle; one breed averaged 8.0 in

shear test and 5.9 in panel rating while another breed averaged 12.6 and

5.2, respectively, for the two methods of evaluation. In a study of loin

steaks from 101 steers sired by nineteen sires, Means and King (1959) re-

ported ratings by a forty-family household panel of 6.4 and 8.1 for sire

averages. The findings of the household panel were substantiated by

Warner-Bratzler shear values of from 6.3 to 22.3. The authors found dif-

ferences between sire progeny groups within breed to be highly significant

thus indicating that tenderness is probably quite heritable even though

no heritabllity estimates were given.

An Oklamona study of sixty Angus steers and heifers produced by

seven different Angus sires and reported by Kieffer et al. (1958) gave an

estimate of 92 per cent for heritability of tenderness as measured by

Warner-Bratzler shear and an estimate for unadjusted rib eye area of 56

per cent. Research by Knapp and Knodskog (1946) gives heritability esti-

mates of 84 per cent for carcass grade and 59 per cent for area of rib

eye. In 1950, Knapp and Clark (1950) published revised estimates for

carcass grade and loin eye area of 33 and 68 per cent, respectively.

Similar findings were reported by Woodward et al. (1954). Clark (1954)

obtained heritability estimates of 16.4 per cent for carcass grade, 72.7

per cent for dressing percentage, 31.5 per cent for thickness of fat over











the rib eye and 67.0 per cent for area of rib eye. These calculations

indicate that more rapid progress could be made in breeding for increased

area of the rib eye than in breeding for carcass grade.

Yao et al. (1950) reported heritability estimates of 19.8 per

cent for tenderness evaluation by panel and 161.8 per cent for Warner-

Bratzler shear value. Knowing it impossible to have a heritability of

over 100 per cent, the authors stated, "The latter value may be affected

by the segregation of factors or the dominance and epistatsis of the

genes." Warwick (1958) gives Shelby's 1958 estimate of 72 per cent for

area of rib eye as a further indication that selection for variation in

carcass composition should be effective.


Meatiness of the Beef Carcass

Evaluating Meatiness

Numerous consumer surveys Indicate that the housewife demands

leanness. With this in mind, research efforts have concentrated on the

production of carcasses with superior muscling, minimum waste fat and

only a moderate amount of bone. The latter factor is of questionable

attainment since the ratio of lean to bone appears to be somewhat con-

stant. With the aim of producing meatier carcasses, evaluation methods

are needed to select those carcasses which actually possess more lean

meat. Since physically separating the beef carcass into lean, bone and

fat is costly and time consuming, other means of improved indicators of

superior muscling are needed for accurate carcass evaluation.

The Ohio work by Cahill et al. (1956),involving forty Hereford

cattle, indicated a direct relationship between the edible portion of











the carcass and the area of Longissimus dorsl muscle at the twelfth rib.

A highly significant correlation of 0.85 was obtained between these two

measurements. The relationship was substantiated by Orme et al. (1957).

In a later report Cahill et al. (1959) noted a positive correlation of

0.68 between the rib eye area and the edible portion of the carcass.

These reports and others have served to justify the use of rib eye area

or Longissimus dorsi muscle area at the twelfth rib as a measure of the

muscling or meatiness of the beef carcass.

Very recently, Cole et al. (1960) reported that area of the

Longissimus dorsi muscle was somewhat inadequate as an indicator of car-

cass lean. The correlation between rib eye area and carcass lean was

only 0.43; correlations between rib eye area and other measures of the

carcass accounted for only 5 to 30 per cent of the variability In carcass

lean. Cole et al. (1960) reported close relationships to exist between

separable carcass lean and separable lean of the round, separable lean of

the chuck and separable foreshank lean with correlations of 0.95, 0.93

and 0.81, respectively. The separable lean of the round, chuck and fore-

shank accounted for 90, 87 and 66 per cent of the variation In total sep-

arable lean of the carcass, respectively.

Several studies Indicate that breed and type influences the area

of rib eye. Damon (1957) noted that Brangus cross steer carcasses had

significantly larger rib eye area than Brahman cross steers. A report by

Stonaker et al. (1952) at the Colorado Station indicated that the rib eye

area of conventional type cattle was significantly larger than rib eye

areas of comprest type Hereford cattle. In a study of various breeds of

cattle, Cole et al. (1958) noted a highly significant difference in area











of rib eye between Angus, Hereford, dairy breeds, Brahman and Brahman

cross steers; further, similar differences between breeds in the percent-

age of separable lean, fat and bone were obtained.

In another study, Cole et al. (1957) noted that the percentage

of separable lean increased and fat decreased as grade changed from Choice

to Standard. Although this finding is not unusual, it might explain the

findings by Robinson (1957) that packers and retailers in Tennessee prefer

to feature cattle of grades lower than Prime. In summarizing consumer

research reports of studies In Arizona, California, Colorado and Texas,

Birmingham (1957) reported that consumers preferred U.S. Good over U.S.

Choice and U.S. Prime cuts at the same price and that of the top four

grades of beef, Prime was least In demand of all grades, even If priced

the same per pound as the lower grades.

A number of reports have Indicated the possibility of progress

through breeding for meatiness, as measured by rib eye area. Shelby

et al. (1955) reported the heritability of area of rib eye to be 72 per

cent; estimates by Knapp and Clark (1950) show area of rib eye muscle to

be 68 per cent heritable. Knapp and Nordskog (1946) reported a herita-

bility estimate of 59 per cent for area of rib eye. A similar estimate

of 67 per cent was reported by Clark (1954) in a study of 635 steers

sired by eighty-eight Hereford sires. Woodward et al. (19541 reporting

on the same group of steers, found that the heavier calves had larger rib

eyes with less external fat and that the area of rib eye was associated

quite closely with the faster gaining calves. Thus selection for in-

creased area of rib eye would compliment selection for faster rate of

gain.












The Relationship of Bone and Meatiness

The U.S.D.A. workers, Hankins et alo (1943), found that muscle-

bone ratio of cattle is a rather definitely inherited character; the

ratio for beef cattle was 2.55:1 while for dual purpose cattle the ratio

was 2.28:1 or indicating that beef cattle have a greater yield of lean

meat per unit weight of bone than dual purpose type cattle.

McMeekan (1956) wrote concerning the relationship of the weight

of cannon bones to muscling, "So strong is this relationship that the

weight (of muscle) could be determined within one per cent if the weight

of the cannon bones are known." He further stated that the finer boned

animals have a smaller amount of lean tissue and a larger amount of fat

than the heavier boned animals on a percentage basis. Hirzel (1939) found

that long bones were detrimental to quality and that bone length had very

little relationship to carcass weight.

Lush (1926) concluded that the most practical Indicator of the

percentage of bone in dressed carcasses was the weight of the four legs

below the knees and hocks. Callow (1940),working with weights of bone

and muscles reported that the ratio between the weight of muscular tissue

and that of bone increases with an increase of percentage of fatty tissue

in a carcass, because during fattening muscular tissue grows more rapidly

than bone. He observed nearly three times as much muscle as bone in a

very lean carcass and in carcasses with 20 per cent fatty tissue there

was nearly four times as much muscle as bone. From these observations,

Callow concluded that carcasses containing 20 per cent fatty tissue, have

slightly more fatty tissue than bone; with very fat carcasses (40 per

cent fatty tissue) there was actually shown four times as much fatty tis-

sue as bone.










These reports, suggesting a pronounced relationship between the

cannon bones (metacarpal and metatarsal bones) and meatiness, gave rea-

son for later investigations concerning muscle-bone relationships. Market

et al. (1958) found little relationship between metacarpal circumference

and rib eye area. The Biceps femoris, Semitendinous and Semlmembranous

muscles of the round were traced and areas correlated with the front

cannon circumference; partial correlation coefficients lacked signifi-

cance in both steers and heifers.

Wesili et al. (1958) reported a simple correlation of .22 and a

partial correlation of .11 between trimmed cannon circumference and rib

eye of 153 Angus, Hereford and Shorthorn steers of similar weight. Sig-

nificant but small correlations were found when live bone score, based on

a I to 9 scale varying from light bone to heavy bone, and live measure-

ments of circumference of left metacarpal and frontal and lateral measure-

ments midway between the knee and pastern joint were correlated with clean

metacarpal measurements. These workers concluded that live measurements

are not too useful for predicting actual bone measurements.

Butler et al. (1956) concluded that bones tend to develop pro-

portionally in beef animals. This finding has been supported by work

conducted by Wythe et al. (1958). These high correlations indicate that

bones develop proportionately both in length and weight. Highly signifi-

cant coefficients of correlation were found between trimmed bone weights

and weights of the sum of loin plus rib plus round, the sum of retail

trimmed rib, chuck, loin and trimmed boneless cushion round, as well as

the area of rib eye. The bones used In this study were the trimmed meta-

carpal, metatarsal, tibia, femur and radius ulna. Length of bones also











correlated with the previously listed wholesale cuts and were found to be

highly significant. In this study, highly significant coefficients of

correlation between bone thickness (weight-length ratio) and the above

named cuts. These coefficients of correlation indicated that a strong

positive relationship between bone thickness and muscling existed in the

twenty-eight steers studied.

Another Texas report by Orts (1959) indicated that cannon bone

weight, area, weight-length ratio and specific gravity hold a high rela-

tionship to wholesale cut weight and rib eye area. Although the corre-

lation coefficients were highly significant, when submitted to a partial

calculation holding chilled carcass weight constant all significance was

lost except for weight of rib which was negatively related to cannon bone

measurement. This indicated an inverse relationship, with carcass weight

constant, between bone characteristics and wholesale rib weight. Data

indicate that bones develop proportionally with age since no change in re-

lationship was noted when age was held constant.

To determine the relationship of muscle to bone, King (1959) made

a study of 132 steers that ranged in age from 150 to 600 days. Carcass

grades ranged from U.S. Standard to U.S. Choice with carcasses weighing

from 215 to 786 pounds. Weights of metacarpal and metatarsal bones cor-

related with rib eye area gave coefficients of .49 and .48, respectively.

Higher correlations were obtained between weights of the two bones and

weights of cushion round, loin, rib, sum of loin, rib and round and

chilled carcass weight. With age held constant, the metacarpal and meta-

tarsal bones from cattle within a breed, weight and age classification

were found reliable indicators of muscling.












Dawson et al. (1955) found a moderately high estimate of herita-

bility of 33.5 per cent for circumference of cannon bone among fifty-

eight milking Shorthorn steers. Thus if increased muscling is associated

with increased size of cannon bones, It would be possible to increase

muscling through breeding for increased size of cannon bones. Hammond

(1952) feels that improvement for beef conformation and muscling consists

in shortening the bones, particularly the extremities and so In thicken-

ing the muscles which lie over them.

Cahill et al. (1959) found a highly significant correlation coef-

ficient of .93 between weight of femur and weight of edible portion of

the carcasses sired by short bodied bulls. Weights of other long bones

correlated positively with edible portion data as did separable muscle of

the 9-11 rib cut and total edible portion of the side.

Although many reports have shown relatively high correlations be-

tween bone weights and lengths with areas of rib eye and total lean of

the carcass, reliability of these indicators when adjusted for carcass

weight is only fair to poor.


Slaughter and Carcass Characteristics of Beef Cattle

Some Factors that Affect Slaughter and Carcass Characteristics
of Beef

Even though slaughter characteristics include dressing percentage,

weights of items removed during slaughter such as feet, head, liver,

gastro-intestlnal tract and contents, pluck (heart, lungs, esophogus and

trachea) and hide, the literature is almost devoid of Information con-

cerning these characteristics except for considerations of the effects of

breeding. Thus slaughter and carcass characteristics will be discussed

primarily in the next section which concerns the effect of breeding.










Dressing percentage is a major consideration in the evaluation of

slaughter cattle since the dressed carcass represents most of the value of

the live animal. Research by the U.S.D.A. by Clark (1954) Indicated that

it may be possible to breed for increased dressing percentage. In a study

involving 635 steers sired by Hereford bulls, Clark (1954) obtained an

estimate of heritability for dressing percentage of 72.7 per cent. An

estimate for the same characteristic by Dawson et al. (1955) of 69.1 per

cent substantiates the finding of Clark (1954) that dressing percentage

heritability is quite high. Warwick (1958) reported the heritability of

dressing percentage to be 73 per cent. Thus it appears that dressing per-

centage would lend itself to effective breeding selection.

Nelson et al. (1930) noted that cattle with higher degrees of fin-

ish tend to have higher dressing percentages. The relationships between

dressing percentage and several slaughter and carcass characteristics was

studied by Woodward et al. (1954) and it was found that dressing percent-

age was slightly related to length of carcass with a correlation coeffi-

cient of .18 which was highly significant. It was noted that dressing

percentage was moderately related to area of rib eye with a correlation

coefficient of .39 which indicates that selection for higher dressing per-

centages would tend to increase the area of rib eye. Woodward et al.

(1954) also found a strong relationship between the length of leg and

length of carcass with a highly significant correlation coefficient of

.77. This Is not too unusual since other workers have found that animals

develop proportionally throughout the entire carcass. It is interesting

to note that area of rib eye was moderately related to length of carcass

and length of leg with correlation coefficients of .38 and .40,










respectively. This finding tends to refute the theory that shorter

bodied cattle would have larger rib eyes and heavier muscling. Woodward

et al. (1954) also stated that contrary to prevailing opinion, it is ap-

parently not possible to estimate accurately individual dressing percent-

ages prior to slaughter in groups of animals of fairly similar quality.

Carpenter (1959) found a highly significant correlation of .45

between carcass grade and dressing percentage. Cole et al. (1957) noted

significant differences between grades in carcass length, length of leg,

circumference of round, depth of sirloin, length and depth of chest.

Knapp and Nordskog (1946) found carcass grade highly heritable with an

estimate of 84 per cent. Clark (1954), however, reported a heritability

for carcass grade of only 16.4 per cent.


Significance of Percentage of Brahman Breeding on Slaughter
and Carcass Characteristics of Beef

A study by Butler et al. (1956) involving Brahman X Hereford and

Hereford steers showed a difference in shrinkage (drift) in holding ani-

mals overnight with Brahman crossbreds showing less loss in weight than

Herefords. Shelby et al. (1955) obtained a heritability estimate of 91

per cent for shrinkage. Carpenter (1959) found no significant difference

in the shrinkage of Brahman and Brahman cross steers. Although Black

et al. (1934) found no significant difference in intransit shrink among

Brahman crossbred and British breeds of cattle, shrinkages were slightly

In favor of Brahman crosses.

Dressing percentage has been found to be strongly influenced by

Brahman breeding and Butler et al. (1956) noted a significant difference

of 2.73 per cent in dressing percentage between Hereford and Brahman X










British crossbreds. The differences were in favor of the Brahman cross-

breds; 1.69 per cent of the difference in dressing percentage was ac-

counted for by weight of contents of the gastro-intestinal tract (fill)

and the remaining 0.68 per cent was attributed to differences in weight

of the empty digestive tract. Pearson et al. (1953) also noted Brahmans

having a significantly higher dressing percentage than British breeds

with dressing per cents of 60.01 and 59.68, respectively. The difference

in dressing percentage was mainly attributed to lighter digestive tracts

from Brahman steers. King (1954) noted similar findings in dressing per-

centage in a study of forty-four steers. Damon (1957) reported a breed

difference in dressing percentage that favored Brahman cross steers which

dressed an average of 59.9 per cent. Cole et al. (1958) found highly

significant differences In dressing percentage favoring Brahman and

Brahman crossbred steers as compared with dressing percentages for Angus,

Hereford, Jersey, Guernsey and Holstein steers.

Several studies have shown differences between animals of pre-

dominantly Brahman breeding and animals of British breeding in weights

of certain items removed during slaughtering. Carpenter (1959) found

heavier feet and hide and lighter weights of gastro-Intestinal tract for

cattle of predominantly Brahman breeding than for cattle of primarily

Shorthorn breeding. Cole et al. (1958) found significant differences in

percentage of hide, caul fat, ruffle fat, visera and gastro-intestlnal

tract between cattle of dairy, Brahman, Brahman cross, Angus and Hereford

breeds. In an earlier U.S.D.A. study, Black et al. (1934) found that

Brahman crossbreds had heavier hides, tails, warm carcass weights and

greater hide surfaces while non-Brahman cattle had heavier heads, tongues,










full stomachs and full intestines. No differences were found in hide

thickness, length of intestines, weights of heart, lungs, spleen, brain,

leg bones and feet, caul or ruffle fats. It was noted that differences

in weight and capacity of the digestive tract could explain the higher

carcass yields of the Brahman cattle.

In 1925, Tomhave (1925) stated, "Among fat cattle, Herefords and

Aberdeen-Angus throw the heaviest hides, with Holstein-Friesians a close

third." Also, Aiegler (1949) states, "The weight of the hide varies with

the breed of cattle. Herefords carry the heaviest hides, followed by the

Aberdeen-Angus, Holsteins and Brown Swiss. Shorthorns and the dairy

breeds carry the lightest hides. Hides from the average run of cattle

slaughtered by the large packing concerns average 7 per cent of the live

weight of the animals. Slaughter records of the purebred steers killed

and dressed in the meats laboratory of the Pennsylvania State College

show that Hereford hides average 8.5%, Angus 7.5% and Shorthorn 6.5% of

the live weight of the animals." Although these reports fail to show the

effect of Brahman breeding on hide weights, they indicate a pronounced

effect of breeding on hide percentage.

Differences in carcass characteristics between Brahman and Brahman

crossbreds and British breeds of cattle have been found in several studies

recently. King (1954) noted that Brahman cross steers had slightly higher

percentages of hind quarter than carcasses from steers of Hereford or

Hereford X Santa Gertrudis breeding. Carpenter (1959) found cattle with

a high percentage of Brahman breeding to have greater lengths of leg and

less thickness of chuck than cattle of lesser amounts of Brahman breeding,

but little differences In length of carcass was noted.










Kleffer et al. (1958) noted significant differences among Angus

sire groups for marbling score, carcass grade and area of rib eye. While

Black et al. (1934) found no significant differences in carcass grade be-

tween Brahman crossbred cattle and Hereford and Shorthorn cattle. Burns

et al. (1958) reported highly significant differences In carcass grade

favoring Angus steers over Brahman steers in a study of Angus, Hereford,

Brahman and Brahman cross steers and also a highly significant difference

between Angus steers and Brahman steers in degree of marbling. Marbling

scores of Angus were 3.6 and for Brahman 2.3 with Hereford and Brahman

cross steers being intermediate in marbling. Damon (1957) noted that

Brahman sired steers had slightly higher carcass grades thah Brangus or

Charolaise sired steers. However, Kincaid (1957) reported that carcasses

from steers of straight-bred British or crosses of British breeds averaged

low Choice; British-Zebu and Zebu-British crosses averaged high Good;

while Brahman, Brangus, Charolaise and their crosses averaged low Good.

Carpenter (1959) found steers of more than one-half Brahman breeding had

lower carcass grades than steers of one-half or more Shorthorn breeding;

the steers have been fed and managed similarly.

Thus It has been found in numerous studies that Brahman or Zebu

animals have significantly higher dressing percentages, greater weights

of feet and hides and lower weights of gastro-intestinal tract either

with or without contents. These cattle often have longer hind legs, less

thickness of chuck, less marbling and lower grading carcasses than animals

of British breeding.










Cutability of the Beef Carcass

The Effect of Finish and Conformation on Beef Cutability

Consumer surveys continually reflect the feeling of housewives

that meatiness and high cutability are of utmost importance. Since

steaks and roasts are in more demand than other cuts of beef, the price

demanded for steak is substantially higher than that for less desirable

cuts of beef. Therefore, carcasses yielding a higher percentage of the

carcass in wholesale cuts such as round, short loin, loin end, rump and

rib would be more desirable and command a higher price per pound for the

carcass than one with low yields of these higher priced cuts.

Finish or fatness of the carcass decreases the yield of higher

priced cuts and total lean meat while superior conformation or shape of

the carcass tends to increase the higher price cut yield. A U.S.D.A.

study of beef cutability by Pierce (1957) showed that higher finish grade

and greater depth of fat Increased the percentages of short loin, rib,

flank, brisket, plate and hindquarter while decreasing the percentages of

round, loin end, chuck and foreshank. The study further indicated that

carcasses with-superior conformation cut larger percentages of round,

short loin, rib, brisket and foreshank and lower percentages of loin end,

chuck, flank, plate and hindquarter. Heavier carcasses had more chuck,

rib, flank, brisket and plate--in other words higher percentages of the

less desirable, lower priced cuts of the carcass. Pierce (1957) also

found that beef carcasses may vary in cutability, or yield of major retail

cuts, by as much as 25 per cent between low and high yielding beef car-

casses or range from 45 to 70 per cent of the carcass weight. Cole et al.

(1957) noted that within the range of Choice through Standard grades,











percentages of round and chuck decreased significantly with grade while

percentages of plate, brisket, kidney knob and flank showed a significant

increase associated with increase in carcass grade.

Pierce (1957) reported that finish Influenced cut-out value much

more than does conformation. Since superior conformation and finish

grade have opposite effects on yield, the net difference In yield from

five wholesale cuts from one grade to another might be calculated to be

slightly less than 1 per cent on a wholesale basis or slightly over 1 per

cent on a retail basis. It was also found that a subjective evaluation

of the carcass was superior to objective methods studied for predicting

yields of lean cuts.

Stonaker et al. (1952) compared Hereford steers of conventional

types with those of the comprest type and found almost no difference in

the percentage of high priced cuts.


Effects of Brahman Breeding on Beef Carcass Cutability

Butler et al. (1956) compared Hereford steers with Brahman X

Hereford steers, the two groups differing greatly in external appearance.

Again only very small and mostly insignificant differences in the per-

centages of high priced cuts were noted between these two groups. An-

other Texas study, King (1954), involving Hereford, Brahman X Hereford

and Hereford X Santa Gertrudis steers indicated that the percentage of

rib, chuck, short loin, loin end and round was slightly lower in carcasses

from the Hereford X Santa Gertrudis steers; however, differences in cut-

out percentages were very slight. In this study, Brahman cross steers had

no significant difference in cut-out values from those of Hereford steers.











Cole et al. (1958), in a study of Jersey, Guernsey, Holstein,

Angus, Hereford, Brahman and Brahman crosses, found differences In cut-

ting yields of the various cuts (wholesale) to be small, although the

dairy breeds had the highest total percentage of round, loin, rib and the

lowest total percentage of thin cuts.

In a study involving sixty-seven steers that varied from as high

as 3/4 Shorthorn-1/4 Brahman blood down through purebred Brahman breed-

ing, Carpenter (1959) found significantly larger percentages of foreshank,

rib, round and loin end and a significantly smaller percentage of plate

among steers of predominantly Brahman breeding. Differences in weight of

chuck, short loin, rump, brisket and flank were small and insignificant.

Connective tissue surrounding the muscle and muscle fibers of meat

has been suggested by Mackintosh et al. (1936) and Brady (1937) to Influ-

ence beef tenderness. These workers feel that large amounts of connective

tissue decrease the tenderness of beef. The greatest concentration of

connective tissue in the animal is in the hide. If the amount of inter-

muscular and Intra-muscular connective tissue is proportional to that

found in the hide, then the question arises as to the relationship between

hide thickness and tenderness. An additional objective of this study was

to determine the relationship between hide thickness and tenderness and

the possible value of hide thickness in predicting tenderness.

Breaking strength of the metacarpal and metatarsal bones was used

by Becker et al. (1953) to determine the effect of different mineral sup-

plements on bone characteristics. Bone breaking strengths of 165 leg

bones from Florida dairy cows indicated wide differences that could be

traced to minerals received by the animals. Chapman et al. (1955) used











bone breaking strength of femur bones as a criteria to determine value of

different sources of phosphorus in swine rations. Carpenter (1959) com-

pared breaking strength of metacarpal and metatarsal bones with tenderness

of steaks evaluated by an organoleptic panel to test for possible rela-

tionships. The correlations of -.04 and -.07 obtained by Carpenter (1959)

between tenderness and breaking strengths leave only slight possibility of

any relationship existing between tenderness and breaking strength of the

cannon bones of cattle. A further objective of this research was to deter-

mine relationships between bone breaking strengths and beef tenderness.














CHAPTER III


EXPERIMENTAL


Design and Animals Used

The 538 animals used in this study were produced at four locations

within the State of Florida. Three hundred and sixteen calves, steers,

heifers, bulls and cows were obtained from the Range Cattle Station, Ona,

and 95 steers and heifers were produced at the Beef Research Unit, Gaines-

ville. The West Central Florida Experiment Station, Brooksville, supplied

85 steers and 40 steers were raised at the Everglades Experiment Station,

Belle Glade.

Over a three-year period, 102 steers from the Range Cattle Station

were divided into four groups and either slaughtered at weaning or fed In

dry-lot for 70, 140 or 210 days and then slaughtered. The steers in dry-

lot were fed to maintain the same carcass grade which they held at weaning.

This feeding-management program provided steers of varying grades and ages

throughout the three-year period. These animals were the nucleus for this

study to which additional animals of other breeds, a wider range of car-

cass grades and a much wider sampling of animal ages, were added. Only 222

of the 538 animals were slaughtered at the University Meat Products Labo-

ratory, Gainesville. The remainder were slaughtered at commercial packing

houses throughout the state.

Only animals of known breeding and calving dates were used in this

study. The breeding of the animals used were Angus, Brahman, Brangus,

30










Devon, Hereford, Shorthorn and Santa Gertrudis and various crosses of

these breeds. The cattle ranged in age from five months to over ninety-

nine months with an average age of slightly over nineteen months. The

carcass grades ranged from low Canner to low Prime and averaged between

high Standard and low Good. Marbling scores of the carcasses ranged from

devoid to abundant with an average slightly above traces.


Slaughter Procedures
Animals raised at the Range Cattle Station and slaughtered at the

University Meat Laboratory were weighed prior to being trucked 225 miles

to Gainesville. Upon arrival, animals were weighed as they were unloaded.

The steers were held overnight with access to water, but feed was with-

held. The following morning the weight of each steer was recorded. This

weight for each animal was used as the slaughter liveweight for computa-

tion of dressing percentages and for a variable used to adjust weights of

slaughter items.

Animals were slaughtered by routine slaughter procedures and

weights recorded for the following items removed from the carcass: weight

of head, feet, hide, gastro-intestinal tract and contents, liver and pluck.

Following slaughter, carcasses were shrouded and placed in a cooler with a

temperature of 340-360F. for forty-eight hours. After the chilling period,

carcasses were weighed to the nearest one-half pound. Carcass grades were

assigned by a Federal meat grader to the nearest one-third of a grade for

conformation, outside finish, inside quality, degree of marbling and over-

all carcass grade.











Carcass Measurement Procedures

Four measurements were made on 125 beef carcasses of animals

slaughtered at the University Meat Laboratory. The carcass measurements

were carcass length, length of leg, circumference of round and thickness

of chuck. Length of carcass was determined by measuring from the anterior

edge of the altch bone to the anterior edge of the first rib. The length

of leg was taken from the anterior edge of the altch bone to the highest

point on the tarsal bones in the hock Joint. Measurement of round circum-

ference was made by computing 60 per cent of the leg length measurement

and Inserting a shroud pin In the inside round that 60 per cent of the

distance measuring down from the highest point on the hock Joint to the

altch bone. Another pin was placed in the outside round the same distance

from the hock joint and an additional pin placed in the bulge of the round

at a point horizontal between the other two pins. A flexible steel tape

measure was placed tightly and in a horizontal plane around the round just

beneath the positioned pins. This measurement was recorded as the circum-

ference of round. The final measurement was thickness of chuck. To ob-

tain this measurement, a beef needle was inserted through the chuck from

inside the carcass Just anterior to the first rib and equidistant from the

first thoracic vertebra and the sternum. The point of the beef needle was

pushed through to the outside of the chuck and with the thumb held tightly

on the beef needle to mark the depth of penetration, the needle was re-

moved and the penetration depth recorded as thickness of chuck. All car-

cass measurements were made to the nearest one-tenth of an Inch.











Carcass Cutting Procedures

The left side of 125 carcasses was cut into wholesale cuts accord-

ing to the detailed procedures outlined by Wellington (1953). Each whole-

sale cut was weighed to the nearest one-tenth pound. The hindquarter was

cut by "Chicago style" and the forequarter by "National style." Details

concerning method of analysis and adjustment factors will be presented in

the statistical analysis section and in discussion of results.


Methodology for Measuring the Metacarpal and Metatarsal Bones

The following measurements were made on cleaned and trimmed meta-

carpal and metatarsal bones of 100 cattle: length of entire bone, width

of bone at center of shaft, depth of bone at same position. An apparatus

with a stationary and a movable, sliding end plate was used to measure the

total length of the bone. With the bone in the apparatus, the distance

from the proximal end of the bone to the epiphyseal Joint at the distal

end was also measured and one-half of this distance was marked on the

shaft as a reference point for measurement of width and depth. Width and

depth of the bone shaft at the reference point was made with a millimeter

caliper to the nearest millimeter.


Procedures Used in Obtaining Bone Breaking Strength Measurements

Metacarpal and metatarsal bones from 100 cattle cleaned of all

muscular and connective tissue were marked with a line at the mid-point of

the shaft. At this point pressure was applied to each bone until maximum

resistance to breaking had been reached. Bones were placed on two metal

fulcrums that were spaced six inches apart from the crest of one Iron to

the other. To measure the breaking strength, a universal testing machine











(Riehle Stress and Tensile Strength testing machine) was used at its

lowest setting to enable accuracy to the nearest five pounds. The testing

machine was placed In low gear and moderate speed maintained and slowly

decreased as pressure increased up to approximately 1000 to 1200 pounds.

At this time speed was reduced to give an Increase in load of 100 pounds

in five seconds. This speed was maintained by varying the speed increase

since as a bone approaches maximum resistance to breakage, only very slow

increases in total load are made. Thus, it was necessary to increase the

speed to insure a continuous rate increase in load. Each bone was broken

and total resistance to breaking recorded to the nearest five pounds.

Breaking strengths of metacarpal and metatarsal bones were compared with

tenderness values of the meat to determine if breaking strength of bones

can be used to predict tenderness of beef.


Method of Measuring Hide Thickness

The thickness of hide of 165 cattle was measured at nine locations.

Locations of measurement were as follows: back of shoulder, middle of

back and just anterior to the tallhead. Three measurements were made on

each side, each being in line with the three positions on the top line and

a point half way to the ventral side of the hide. The points of measure-

ment are as shown in Figure 1.


Tenderness Sampling Technique

After forty-eight hours of chilling, a sample of short loin, ap-

proximately six inches in length measured from anterior edge of short loin,

was removed from the left side of each carcass and immediately wrapped for

freezer storage. Short loin samples were frozen at OOF. until tests were











































































Figure 1

Location of Points at Which Hide Thickness Was Measured

.0










made. Steaks one inch in thickness were cut using a band saw from frozen

short loin sections.


Measurement of Lonqissimus Dorsi Area

The anterior surface of the anterior steak at the thirteenth rib

was used an an Indication of meatiness as well as tenderness and the

Longissimus dorsi muscle (rib eye) was traced with a soft pencil on opaque

tracing paper. The area of this muscle was then traced using a compensat-

ing polar planimeter to determine the area of rib eye to the nearest one-

hundredth of a square inch.


Tenderness Evaluation by Subjective and Objective Methods

After thawing at 36F. for twenty-four hours, steaks were broiled

in electric ovens to a uniform "medium well" degree of doneness (approxi-

mately 1640F. internal temperature). During the first two years of the

study, adjacent steaks were used for taste panel and Warner-Bratzler shear

evaluations; however, the third year to enable the tenderness panel to

evaluate the same sample tested by Warner-Bratzler shear, cores for shear

were taken from the same steak that was later tested by taste panel. Usu-

ally eight steaks, representing eight animals, were tested at one panel

session and duplicate steaks from these animals were tested later that day

to give replication of the taste panel ratings and Warner-Bratzler shear

scores.

A trained four member tenderness panel was used consistently

throughout the entire study. To avoid possible variation in tenderness

within the muscle, panel members consistently received samples from the

same area of the steak. Panel member 1 received sample 1; panel member 2,











sample 2; panel member 3, sample 3 and panel member 4, sample 4, as shown

in Figure 2. Samples for panel evaluation were obtained by cutting across

the Longissimus dorsi muscle perpendicular to its long axis as illustrated

in Figure 2. Samples were coded alphabetically, served to the panel and

rated using a tenderness scale from one to six with one being Inedible;

two, extremely tough; three, slightly tough; four, average in tenderness;

five, above average in tenderness; and six, excellent in tenderness.

Three cores, one-half inch in diameter, were removed from the

Longissimus dorsi muscle after it was removed from the broiled steak and

trimmed of external fat and connective tissue. The shear core areas were

held constant in all steaks and cores were identified by area from which

removed as well as by animal. Areas of core removal were designated 1, 2

and 3 numbering from top to bottom of the steak as shown in Figure 2. An

objective evaluation for tenderness, the Warner-Bratzler shear apparatus,

was used to give an additional determination of beef tenderness. Warner-

Bratzler shear values were recorded by area of the steak from which the

cores were removed. Each one-half inch core was sheared twice and with

three cores per steak and two steaks per animal, the total number of shear

values used in computing the shear average was twelve.


Statistical Analysis

All data were punched on IBM cards and analysis accomplished by

use of the least squares method of analysis of a multiple regression

system. The analysis was completed on an IBM 650 magnetic drum computer.

Analysis was according to Snedecor (1956) and Brandt (1949). To obtain

simple relationships between certain variables, simple correlation
















































Figure 2

Steak Sampling Procedure for Tenderness Evaluation
by Panel and Warner-Bratzler Shear







39


coefficients were computed from sums of squares and cross products of data

prior to matrix inversion. The multiple regression analyses and partial

regression coefficients were computed by the IBM 650 computer.

Estimates of heritability for tenderness were computed and sug-

gested by Dawson et al. (1955).














CHAPTER IV


RESULTS AND DISCUSSION


Beef Tenderness

Animals Used to Determine the Relative Significance of
Factors Affecting Beef Tenderness

Tenderness evaluations and carcass grade components for 538 cattle

from four locations within the State of Florida were analyzed to determine

the relationships between those certain carcass grade factors and tender-

ness. The cattle were of known breeding and age and were sired by Angus,

Brahman, Brangus, Brahman X Devon, Devon, Hereford, Brahman X Shorthorn,

Shorthorn and Santa Gertrudis bulls. Table 1 shows the numbers of animals

sired by each of these breed, the number of sires in each breed as well as

the number of cattle grouped into five percentages of Brahman breeding.


The Relationship of Finish and Marbling to Tenderness

The degree of carcass outside finish had a similar relationship to

tenderness evaluations as marbling. The simple correlations between finish

and tenderness of .12 and -.11 were highly significant indicating a defi-

nite relationship with tenderness. Simple correlations shown in Table 2,

however, indicate that outside finish accounted for only 1.5 and 1.2 per

cent of the variability in tenderness by panel and shear, respectively.

The magnitude of the relationship of marbling with tenderness was

quite low although highly significant, as shown by the correlation coeffi-

clents of .12 and -.13 between marbling and tenderness measurements by

40
















TABLE 1

SIRES AND PERCENTAGES OF BRAHMAN BREEDING OF 538 CATTLE USED IN
DETERMINING THE RELATIVE SIGNIFICANCE OF FACTORS INFLUENCING
BEEF TENDERNESS


Breed of
Sire

Angus

Brahman

Brangus

Brahman X
Devon

Devon

Hereford

Brahman X
Shorthorn

Shorthorn

Santa
Gertrud s

Total


No.
Sires

15

21

5


2

2

12


8

11


No.
Progeny

84

196

18


14

12

48


22

122


22

538


Percentage of Brahman Breeding in Progeny
1 2 3 4 5
(more than (less than
75%) (75%) (50%) (25%) 25%)

-- -- 25 13 46

108 75 13 -- -

-- -- 1 17


14

6

1


18

122


108
















TABLE 2

THE RELATIONSHIP OF OUTSIDE FINISH AND MARBLING TO TENDERNESS AS
SHOWN BY SIMPLE CORRELATIONS AND SIMPLE AND PARTIAL
REGRESSION COEFFICIENTS

Variability Accounted
Coefficients for Per Cent
Item Panel Shear Panel Shear

Simple correlations
Outside finish and
tenderness .12** -.11** 1.5 1.2

Marbling and tenderness .12** -.13** 1.5 1.8


Simple regressions
Outside finish and
tenderness .116** -.281** -- -

Marbling and tenderness .232** -.617** --- --


Partial regressions
Tenderness on outside
finish with age and
percent Brahman breeding
held constant -.014 -.008

Tenderness on marbling
with age and per cent
Brahman breeding held
constant .115** -.193 --


**Significant at .01 level of probability.











panel and shear, respectively. Marbling accounted for 1.5 and 1.8 per

cent of the variability in tenderness by panel and shear.

The largest simple regression coefficient was tenderness on mar-

bling and shows a coefficient of .23. The reciprocal of this value is

4.31 and thus increasing the average marbling score from 3.40 to 7.71

would Increase the panel tenderness score from 4.09 to 5.09. An increase

in one variable,such as marbling, would move with increase in other highly

correlated variables,such as per cent of Brahman breeding, which in them-

selves might be associated with tenderness; thus simple regression coeffi-

cients lack in reliability in predicting tenderness. Therefore, partial

regression coefficients which show the effect of an independent variable

on a dependent variable are more reliable since other independent variables

have been held constant.

It is interesting that even though the partial regression coeffi-

clents of tenderness on outside finish were not significant, the coeffi-

cient for panel tenderness was negative, Indicating that increased outside

finish had a depressing effect on panel tenderness scores.

Marbling had a highly significant positive partial regression co-

efficient of .115 on panel score and would require an Increase of 8.7

degrees of marbling to increase the average panel score one unit. Since

marbling averaged 3.3, all carcasses would have to possess extremely abun-

dant marbling to increase the panel score from 4.09 to 5.09. The partial

regression coefficient for marbling on shear was an insignificant -.193.











The Relationship of Conformation to Tenderness

Carcass conformation or desirability of carcass shape Indicated a

modest relationship with tenderness evaluations with highly significant

correlation coefficients of .16 and -.21 for tenderness measured by panel

and shear, respectively. The relationship between conformation and ten-

derness is shown in Table 3 by simple correlations, simple and partial

regression coefficients. Although the simple correlations indicated slight

relationships with tenderness, conformation variations accounted for only

2.6 and 4.5 per cent of the variability In tenderness by panel and by

Warner-Bratzler shear force, respectively. Even though simple regression

coefficients for the effect of conformation on tenderness are substantially

higher than partial regression coefficients with age and percentage Brahman

breeding held constant, the significant partial regression coefficients of

.068 and -.260, respectively, for panel and shear evaluations indicate a

positive but modest relationship between carcass conformation and tender-

ness. Although holding percentage of Brahman breeding constant caused a

reduction in partial regression coefficients, the effect of desirable beef

type continued to demonstrate a significant relationship with tenderness

of beef.

The partial regression coefficients for the relationship of con-

formation with tenderness indicate that carcass conformation would only

need to be increased 3.7 units, or from low Good to average Choice, to de-

crease the average shear score one unit. However, to increase the

panel tenderness score one unit would require an increase of 14.7 units in

conformation. Therefore if all carcasses had a conformation score of high

Prime, panel tenderness scores would only be increased about .50 on the


















TABLE 3

THE RELATIONSHIP OF CONFORMATION AND TENDERNESS AS SHOWN BY
SIMPLE CORRELATIONS AND SIMPLE AND PARTIAL
REGRESSION COEFFICIENTS

Variability Accounted
Coefficients for Per cent
Item Panel Shear Panel Shear

Simple correlation
Conformation and
tenderness .16** -.21** 2.6 4.5

Simple regression
Tenderness on
conformation .144** -.421** -- --

Partial regression
Tenderness on con-
formation with age
and per cent Brahman
breeding held
constant .068* -.260** -- --


**Significant at the .01 level of probability.

* Significant at the .05 level of probability.











panel tenderness scale. Carcass conformation was found to be significantly

related to tenderness evaluations by panel and shear, but like other car-

cass grade components, the relationship was not high.


The Relationship of Animal Age at Time of Slaughter and Tenderness

It may be noted in Table 4 that the correlations between tender-

ness and animal age at time of slaughter were quite low with correlation

coefficients of -.05 and .05 for tenderness evaluation by panel and shear,

respectively. In this study, age accounted for only 0.3 per cent of the

variability in tenderness evaluations by either method. Thus increasing

age at time of slaughter had a negative effect on tenderness but the re-

lationship was extremely low and not statistically significant. Animal

age showed a simple regression coefficient of -.017 for panel tenderness

indicating that a decrease of 47.5 months in the average age of the animals

at time of slaughter would increase the panel tenderness score from an

average of 4.09 to an average of 5.09. But when conformation, outside

finish, marbling and percentage Brahman breeding were held constant, the

relationship of age with tenderness as shown by the partial regression co-

efficients of -.009 and .015, respectively, for panel and shear indicated

that the average slaughter age would have to be reduced 107.5 months to

Increase the panel average from 4.09 to 5.09. Further, the average age at

time of slaughter could lower the average shear value one unit by decreas-

ing the average slaughter age 65.3 months. Therefore it appears that

slaughter age was not even slightly related to tenderness and that increas-

ing or decreasing the age at slaughter within practical limits would have

little effect on the tenderness scores by panel and shear.




















TABLE 4

THE RELATIONSHIP OF ANIMAL AGE AT TIME OF SLAUGHTER WITH TENDERNESS
AS SHOWN BY SIMPLE CORRELATIONS AND SIMPLE AND PARTIAL
REGRESSION COEFFICIENTS

Variability Accounted
Coefficients for Per Cent
Item Panel Shear Panel Shear

Simple correlation
Age and tenderness -.05 .05 0.3 0.3

Simple regression
Tenderness on age -.017 .046 -- --

Partial regression
Tenderness on age with
conformation, outside
finish, marbling and
per cent Brahman
breeding held
constant -.009* .015 -


*Significant at the .05 level of probability.










These results do not substantiate the findings of Miner and

Hankins (1950) and Mackintosh et al. (1936) who reported that tenderness

was markedly decreased by Increased animal age at time of slaughter. This

could have resulted from other variables not being controlled when the re-

lationship of age and tenderness was studied.


The Relationship of Carcass Grade and Tenderness

Carcass grade showed a highly significant relationship with ten-

derness evaluations with correlation coefficients of .18 and -.22 for

panel and shear score, respectively. These correlations are slightly

higher than correlations between finish, marbling, conformation, age at

slaughter and tenderness evaluations. However, variations in carcass

grade explained Just 3.2 and 4.8 per cent of the variability in panel and

shear evaluations, respectively. Similar results were reported by

Brannaman et al. (1936) and Barbella et al. (1939); however, Cover et al.

(1958) reported a significant correlation of -.226 between carcass grade

and shear evaluation. Carpenter (1959) found no significant relationship

between carcass grade and tenderness with correlation coefficients of .15

and -.08 between carcass grade and tenderness by panel and shear,

respectively.

In Table 5 simple correlation, simple and partial regression co-

efficients are shown between carcass grade and tenderness evaluations.

Simple regression coefficients of .153 and -.431 for carcass grade on ten-

derness by panel and shear, respectively, indicate that increases of 6.5

units in carcass grade, or for example from low Good to low Prime, would

produce an increase of one unit in tenderness score by panel and 2.3 units






















TABLE 5

THE RELATIONSHIP OF CARCASS GRADE WITH TENDERNESS AS SHOWN BY SIMPLE
CORRELATIONS AND SIMPLE AND PARTIAL REGRESSION COEFFICIENTS

Variability Accounted
Coefficients for Per Cent
Item Panel Shear Panel Shear

Simple correlation
Grade and tenderness .180** -.219k* 3.2 4.8

Simple regression
Tenderness on grade .153** -.431** -- --

Partial regression
Tenderness on grade
with age and per cent
Brahman breeding held
constant .118** -.367**


**Significant at the .01 level of probability.











increase in grade would decrease the average shear score one unit. When

percentage of Brahman breeding and animal slaughter age were held con-

stant, the partial regression coefficients of tenderness on carcass

grade showed that an increase in carcass grade of 9.3 units would in-

crease the average panel score from 4.09 to 5.09. Partial regression

coefficients for tenderness on carcass grade were highly significant

with coefficients of .118 and -.367 for panel and shear, respectively.

Further, an increase of only 2.7 units In carcass grade, almost a full

carcass grade, would show a decrease of one unit In the average shear

value. Thus carcass grade was significantly related to tenderness by

both methods of evaluation; however, the relationship was relatively low

as has been found in many previous studies.

Relationship of Breeding to Tenderness

The effect of breed of sire on tenderness as evaluated by panel

Indicated that progeny sired by Brahman and Brahman X Shorthorn bulls

were significantly less tender than progeny by Devon bulls. The effect

of breed of sire, percentage Brahman breeding of progeny and location

are shown in Table 6. It may be noted that animals of 50 par cent or

more Brahman breeding were significantly less tender by panel than anle

mals of less than 25 per cent Brahman breeding while animals of 75 per

cent or more Brahman breeding were significantly less tender than progeny

of less than 25 per cent Brahman breeding when evaluated by shear method.

Location also showed a pronounced effect on tenderness with ani-

mals produced at the West Central Florida Experiment Station and at the

Range Cattle Station being significantly less tender by panel and shear

than animals produced at the Everglades Experiment Station.










TABLE 6

EFFECT OF BREEDS OF SIRE, PERCENTAGE BRAHMAN BREEDING OF PROGENY
AND LOCATION ON TENDERNESS EVALUATIONS BY PANEL AND SHEAR

Panel Tenderness Shear Tenderness
Unadjusted Partial Unadjusted Partial
Means Regression Means Regression
I term CoefficientI Coeffic ient'

Breed of Sire2
Angus 4.92 -.0339 8.77 .0378
Brahman 3.60 -1.0467* 11.53 2.1701
Brangus 4.06 -.4295 9.84 .7472
Brahman X Devon 4.39 -.5299 9.01 .8537
Devon 5.13 0.00 8.14 0.00
Hereford 4.69 -.3456 8.93 .0927
Brahman X Shorthorn 3.49 -1.0434* 11.89 2.4881
Shorthorn 4.11 -.4164 10.70 1.3826
Santa Gertrudis 3.76 -.8680 10.41 1.1233

A3 19.92 -.0155* 19.92 .0444*

Percentae Brahmen
Breding of Pr aonv3
More than 75 per cent 3.61 -.6330** 11.25 .9211*
75 per cent 3.60 -.7061** 11.95 1.1650**
50 per cent 4.10 -.4450** 10.28 .6538
25 per cent 4.38 -.2107 9.87 .3748
Less than 25 per cent 4.59 0.00 9.41 0.00

LWut n3
Beef Research Unit 4.95 .1416 8.95 .4390
Everglades Exp. Stat. 4.64 0.00 8.78 0.00
W. Central Fla. Stat. 4.09 -.7106** 9.78 1.2764*
Range Cattle Stat. 3.75 -.7419** 11.31 2.1465**

Partial Regression Coefficient Least squares effect expressed
as partial regression coefficient (Age) or deviation from standard (Devon
sires, Less than 25 per cent Brahman breeding of progeny and Everglades
Experiment Station, Belle Glade).
2Breed of Sire The effect of breed of sire was adjusted for age
and location, i.e. percentage Brahman breeding in progeny not included.
3Age, location and Percentage Brahman breeding of progeny were con-
sidered simultaneously.
**Departure from standard significant at .01 level of probability.
Departure from standard significant at .05 level of probability.










In Table 7 are given the average panel and shear scores for sire

groups of Angus, Brahman, Hereford and Shorthorn breeds. It may be seen

that average panel scores and shear scores vary widely within certain sire

breeds, particularly within the Brahman sires. The range among Angus sire

groups is from 5.88 for sire 116 and 4.68 for sire 113; however, panel

scores among Brahman sires cover a range from 4.50 for sire 205 down to

1.75 for sire 299 and the next lowest average score was 2.75 for sire 200.

Even though Brahman progeny were decidedly less tender than other sire

breeds, variations between sires of the Brahman breed were quite pronounced

and Indicated the possibility for more rapid improvement of tenderness

among Brahman sires than among sires of other breeds.

Among Hereford sire groups the range in panel scores was from 5.63

for sire 617 to 4.00 for sire 604 while among Shorthorn sires, average

panel scores ranged from 4.56 for progeny by sire 707 to 3.25 for progeny

by sire 702 and with the next lowest panel average of 3.54 for offspring

of sire 717. Average shear scores for sire breed groups reflected similar

variations in tenderness with the greatest variation in shear scores among

sire groups of the Brahman breed.

The effect of breed of sire on progeny tenderness as evaluated by

panel is shown In Table 8. It may be noted that 86.7 per cent of Angus

progeny studied had tenderness scores of average or above while Brahman

progeny were predominantly below average in tenderness with only 36.3 per

cent of these carcasses having scores of average or above. Brangus sired

progeny were slightly above average in tenderness with 57.2 per cent of

the carcasses having panel scores of average or higher. Brahman X Devon

sired carcasses had 63.7 per cent of panel scores average or above and










TABLE 7

AVERAGE TENDERNESS SCORES BY PANEL AND SHEAR FOR ANGUS, BRAHMAN,
HEREFORD AND SHORTHORN SIRES

Number Tenderness
Sire Number Progeny Panel Shear


Angus Sires


4.94

4.71

5.30

5.63

4.68

5.75

4.88

5.88

4.83

5.10

5.25


Brahman Sires

4


7.48

9.76

8.21

7.25

9.64

7.43

10.10

6.98

9.50

7.58

8.50


14.95

10.97

13.00

12.60

8.65

12.10

14.30

12.11


200

204

205

206

206

208

210

212


2.75

3.04

3.50

3.67

4.50

4.00

3.25

3.38













Sire Number Pr


603

604

605

607

609

612

613


TABLE 7--Continued

Number Tenderness


ogeny Panel

Brahman Sires (cont.)

37 3.31

1 4.25

1 4.00

4 3.69

15 3.62

7 4.18

6 4.25

27 4.21

29 3.55

16 3.31

3 3.67

3 3.92

1 1.75


Hereford Sires

3

7

9

5

1

4

8


5.00

4.00

4.44

4.95

5.50

5.25

4.53


Shear


11.78

7.00

8.70

11.40

12.03

10.80

10.07

10.06

11.43

12.99

10.73

9.53

16.20


7.07

9.96

9.28

8.88

8.10

7.90

9.81


--











TABLE 7--Continued

Number Tenderness
Sire Number Progeny Panel Shear


Hereford Sires (cont.)

4 4.81


5.13

5.63

5.25

4.75


Shorthorn Sires

1



4

2

31

13

6

20

28

10

7


3.25

4.50

4.56

4.25

4.08

3.98

3.54

4.21

4.15

4.33

3.89


8.30

8.25

7.45

9.00

6.40


16.40

7.80

10.78

11.30

10.30

10.38

12.25

9.61

11.01

10.56

13.26


614

615

617

618

699


702

703

707

708

714

716

717

718

720

722

725




















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only 36.3 per cent below average. Devon progeny were the most tender on

the average with all carcasses having tenderness panel scores above aver-

age. Devon and Angus progeny also had more than 50 per cent of their car-

casses receiving panel scores of above average to excellent. Hereford

progeny also had a high percentage, 87.4 per cent, of carcasses receiving

panel scores of 4 or above. Progeny sired by Brahman X Shorthorn bulls

had only 36.2 per cent of carcasses with tenderness scores of 4 or better

while 63.8 per cent of their carcasses were below average in tenderness.

Low panel scores were found for 43.2 per cent of progeny sired by Shorthorn

bulls while less than one-half the Santa Gertrudis sired carcasses received

panel scores of average or higher and 56.7 per cent were below average in

tenderness by panel.

Brahman and Brahman X Shorthorn progeny had scores of less than

average for two-thirds of their carcasses while Shorthorn, Santa Gertrudis

and Brangus sired progeny showed tenderness scores of average or above for

about one-half the carcasses. Angus, Devon and Hereford progeny had car-

casses with more than 85 per cent receiving panel scores of average to

excellent in tenderness as evaluated by panel. These data suggest a pro-

nounced relationship of breed of sire with tenderness.

The 538 animals in this study were grouped by percentage of Brahman

breeding to study the effect of Brahman breeding on beef tenderness. Breed

group 1 contained animals with more than 75 per cent Brahman breeding while

breed group 2 had animals with 75 per cent Brahman breeding. Breed group

3 was composed of animals with approximately 50 per cent Brahman breeding.

Group 4 contained animals of 25 per cent Brahman breeding and the 5 group

had animals with less than 25 per cent Brahman breeding. Average












tenderness scores by panel and sheer for each breed group are given In

Table 9. All breed groups were compared to breed group 5 and tenderness

differences shown are between this group and the other four groups.

The average panel and sheer scores in this study were 4.09 and

10.45, respectively. Breed group I and breed group 2 were similar in

tenderness but otherwise tenderness by panel increased and shear force

values decreased as percentage of Brahman breeding decreased. Average

panel scores were 3.96, 3.88, 4.14, 4.38 and 4.59 for breed groups I

through 5, respectively, when adjusted for age and location. Carcasses

from animals of groups I, 2 and 3 were significantly less tender than

carcasses of breed group 5. No difference in tenderness was found be-

tween breed groups 4 and 5 by either method of tenderness measurement.

Breed group 2 was slightly less tender than I by shear evaluation.

It may be noted in Table 9 that breed groups I and 2 were significantly

less tender than group 5. Average shear scores were 10.33, 11.06,

10.06, 9.79 and 9.41 for breed groups I through 5, respectively. In

this study, carcasses with higher percentages of Brahman breeding were

significantly less tender than animals of primarily European breeding.

Figure 3 compares the tenderness of Brahmen, Brahman X

European crossbred and European progeny. Among progeny by Brahman

sires tenderness scores by panel were largely below average in tender-

ness. Yet progeny by European sires showed a large percentage of panel

scores above average to excellent. It may be noted further that progeny

by Brahman X European sires were intermediate in tenderness between

Brahman sired progeny and European sired progeny.























TABLE 9

EFFECT OF PERCENTAGE OF BRAHMAN BREEDING OF PROGENY ON
AVERAGE TENDERNESS SCORES


Percentage Brahman Breeding of Proaenv
I 2 3 4 5
(more than (less than
Ten.dernearm 751) (751,) 501) (25 251)

Panel averageI 3.96** 3.88** 4.14** 4.38 4.59

Shear averageI 10.33 11.06** 10.06 9.79 9.41


Tenderness average* adjusted for age and location.

*DeNparture from group 5 significant at .01 level of probability.

Departure from group 5 significant at .05 level of probability.
























40o




>.

I.



20-
4-
.! 20
4-




I10


Figure 3

Effect of Brahman Breeding of Sire on Tenderness of Progeny
As Evaluated by Tenderness Panel


"- Brahman progeny 196
Brahman X European progeny 76
.. European progeny 266


2 to 3 3 to 4 4 to 5 5 through 6
Panel Scores


1 to 2












Tenderness ieritabiliti-es

Estimates of heritability are indicative of the rates of progress

which could be expected in breeding and selecting for a particular

trait. Clark (1954) commenting on heritability states, "The herit-

ability of a characteristic is the fraction of the phenotypic variance

which is due to difference in the heredity of the individual members of

the population Methods used to estimate heritability are based on the

fact that related individuals resemble each other more closely than

unrelated individuals."

Estimates of heritability for tenderness were computed from the

within breed correlation of half-sibs and the resulting correlation

multiplied by four. Estimates of heritability computed by this method

were 67.12 and 27.60 per cent for tenderness evaluate n by panel and

sheer, respectively. These estimates indicate that tenderness is moder-

ately to highly heritatle and that selecting and breeding for tenderness

would be effective.

The intraclass correlation of offspring by the same breed of sire

was .1712 and .0540 for panel and shear, respectively. If the assump-

tion is made that the genetic relationship between calves by the same

breed of sire is 25, heritability estimates of 68.5 and 21 6 per cent

are obtained for panel and shear, respectively. It may be noted that

estimates of tenderness by these two methods produce very similar

heritability estimates. These estimates are lower than those obtained

by Kieffer et al. (1958) working with Angus steers and heifers; the

Oklahoma workers reported a heritability estimate of 92.0 per cent for

tenderness evaluation using the Warner-Bratzler shear method.























TABLE 10

HERITABILITY ESTIMATES FOR TENDERNESS BY PANEL AND SHEAR BASED
ON INTRACLASS CORRELATION OF OFFSPRING BY THE SAME SIREI


Her tabi I ity
Pane Sheer
Method of Estimate Per Cent Per Cent

Within breed correlation of
half-sibs x 4 67.12 27.60
(64 sires 525 progeny)


IThe intracless correlation of offspring by the same breed of
sire was .1712 and 0540 for panel and shear, respectively. If the
assumption is made that the genetic relationship between calves by
the same breed of sire is .25, heritability estimates of 68 5 and 21.6
per cent, respectively, for panel and shear are obtained. This method
of estimating heritability has not been reported previously.










The Relative Significance of Factors Influencing
and/or Associated with Beef-Tenderness

The relative significance of factors Influencing and/or associated

with beef tenderness is shown in Table 11. The greatest percentage of

variance of tenderness by panel accounted for was by percentage of Brahman

breeding of progeny. This variable explained 12.05 per cent of panel va-

riability while carcass grade variations accounted for 9.24 per cent of

panel variance. Percentage of Brahman breeding of progeny was able to

account for more variability in panel scores than slaughter age, conforma-

tion, outside finish and marbling combined. Also breeding accounted for

almost as much variability in shear values as the combined effects of

slaughter age, conformation, outside finish and marbling. Carcass grade

ranked second in importance for tenderness as measured by panel; however,

grade accounted for more variability in shear value than any other variable.

Outside finish, conformation and marbling accounted for only 3.13,

2.55 and 1.06 per cent of the variability in tenderness as measured by

panel. The lowest in importance for tenderness was animal age at time of

slaughter which only explained 0.26 per cent of panel tenderness variabil-

ity. It is interesting that carcass grade was able to account for more

variability in panel tenderness scores than the combined effects of age at

slaughter, conformation, outside finish and marbling. This suggests the

possibility that the Federal meat grader is more reliable in predicting

tenderness through the carcass grade assigned than the separate factors

determining carcass grade.

Carcass grade accounted for 10.40 per cent of the variability In

shear values and was the greatest single factor influencing evaluation of



















TABLE 11

THE RELATIVE SIGNIFICANCE OF FACTORS INFLUENCING AND/OR
ASSOCIATED WITH BEEF TENDERNESS


Factor

Percentage of Brahman breeding

Carcass grade

Outside finish

Carcass conformation

Marbling

Slaughter age of animal


Percentage of Variance Accounted
for by Factor'
Panel Shear
Tenderness Tenderness

12.05 5.41

9.24 10.40

3.13 2.25

2.55 0.47

1.06 2.93

0.26 0.29


IPercentage of variance in tenderness accounted for derived by
partitioning the respective variances for the factors considered.


~ _I~__ ~_ _~_ _______ ___ _____ _I _~ _____ _I~_ ____1_ ___ ___I~_ ____ _____ I__ __











tenderness by Warner-Bratzler shear technique. Percentage of Brahman

breeding explained 5.41 per cent of the shear variability and was able to

account for as much shear variation as the combined effects of outside

finish, conformation, marbling and slaughter age of the animal. Outside

finish, carcass conformation, marbling and animal slaughter age accounted

for 2.25, 0.47, 2.93 and 0.29 per cent, respectively, of the variability

in shear values.

The apparent minor roles of marbling and animal age at slaughter

indicated in this study question the concepts that these two factors are

effected in predicting beef tenderness. Further, these data indicate that

breeding techniques could be employed to improve beef tenderness and also

that breeding could offset advantages in tenderness gained through decreased

age and increased marbling, conformation and outside finish.


Tenderness Variations Within the Longissimus
Dorsi Muscle

Tenderness variations within a single muscle have been reported by

Weir (1953) and Ramsbotton et al. (1944). Further, Ginger and Weir (1958)

noted that within a muscle, Warner-Bratzler shear was less sensitive in

detecting differences in tenderness than a trained sensory panel. The

latter finding substantiates the assumption that a trained tenderness panel

reflects more accurately the true tenderness of beef.

In attempting to control variations in tenderness within the

Longissimus dorsi muscle, each panel member received steak samples, as in-

dicated in Figure 2, from a particular location of the muscle and cores

for Warner-Bratzler shear were taken, as indicated in Figure 2, from three

different locations within the muscle. Thus, direct comparisons between











panel members and shear cores from these locations within the steak were

made to determine if the panel member's score was more related to the shear

score for his respective area of the muscle than to shear scores of other

areas. Table 12 shows the average scores for panel members and shear area

by percentage of Brahman breeding. The average score for panel members

indicated that tenderness values by panel member 2 were the highest fol-

lowed closely by values by panel member I. Lower tenderness scores by

panelists 3 and 4 Indicated either that the lower portion of the loin eye

muscle was less tender than the upper portion or that a real difference in

evaluating tenderness existed among the panel. However, these same trends

were also noticed among average shear areas since average shear area score

tended to increase from area 1 with an average value of 10.28 to area 3

with an average of 11.59.

It may be noted that each panel member was able to detect a sig-

nificant tenderness difference between the three groups with the highest

percentage Brahman breeding and breed groups. Panel member 4 was also able

to detect that carcasses from breed group 4 were significantly less tender

than carcasses of breed group 5. Warner-Bratzler shear values Indicated

significant breed differences in tenderness between i, 2 and 5 breed groups

with the latter group being more tender. Each shear area showed these

differences except for shear area 2, the center of the Longissimus dorsi

muscle, which found a tenderness difference only between groups 2 and 5.

Thus the panel seemed slightly more sensitive In detecting tenderness dif-

ferences between breed groups than the shear method. Average tenderness

scores also indicated that the Longissimus dorsi muscle was more tender in

the center and top of the muscle, the portion nearest the dorsal process

of the vertebra, than the lower portion of the muscle.














TABLE 12
THE EFFECT OF PERCENTAGE OF BRAHMAN BREEDING ON AVERAGES OF
TENDERNESS SCORES AND AVERAGE TENDERNESS SCORES BY
PANEL MEMBERS AND SHEAR AREAS


Percentage of Brahman Breeding
1 2 3 4 5
(more than (less than
Item Average 75%) (75%) (50%) (25%) 25%)

Panel Ave. 3.93 3.61** 3.60** 4.10* 4.38 4.59

Member 1 3.92 3.60** 3.60** 4.07** 4.34 4.58

Member 2 4.18 3.98** 3.87** 4.27** 4.56 4.64

Member 3 3.84 3.53** 3.49** 4.11* 4.39 4.54

Member 4 3.78 3.44** 3.42** 3.91* 4.22* 4.57

Shear Ave. 10.88 11.25** 11.95** 10.28 9.87 9.41

Area 1 10.28 10.64** 11.33** 9.78 9.29 8.76

Area 2 10.76 10.89 11.83** 10.18 9.96 9.65

Area 3 11.59 12.33* 12.59** 10.96 10.38 9.80


**Significantly different at .01 level from breed group 5.

* Significantly different at .05 level from breed group 5.











Relationships between panel tenderness scores and shear area

scores are shown in Table 13. Panel member's scores correlated with

average panel scores with correlation coefficients of .68, .78, .81 and

.78 for panel members 1 through 5, respectively. Correlation coefficients

between panel member scores were of lower magnitude but all were highly

significant. Carcass grade correlated significantly with average panel

score and panel member's scores with coefficients of correlation of .18,

.11, .12, .17 and .18 for panel average and scores for members I through

4, respectively. There was a trend for higher correlations between car-

cass grade and panel member as the panel member sample area neared the

lower end of the steak. Therefore, it appeared that the influence of car-

cass grade on tenderness as measured by tenderness panel was of greater

magnitude In the less tender areas of the muscle--the lower portion away

from the dorsal process of the vertebra. The average panel score corre-

lated with shear average and shear areas with highly significant correla-

tions of -.58, -.90, -.44 and -.49 for shear average and areas 1, 2 and

3, respectively. Shear area 1, the uppermost portion of the muscle,

showed a remarkably high correlation with the average of the tenderness

panel while the lowest correlation between panel average and shear area 2

indicated this location to be only moderately effective in predicting ten-

derness as evaluated by panel. It will be noted that panel member 1 corre-

lated more closely with shear area 1 than other panel members with a highly

significant correlation coefficient of -.55. The further removed the panel

member from location shear area 1, the lower the correlation coefficient.

Panel member 2 correlated with shear area 2 with a significant correlation

coefficient of -.36 while panel member 3 correlated with this shear area















TABLE 13

RELATIONSHIPS BETWEEN TWO METHODS OF TENDERNESS EVALUATION AND AMONG
PANEL MEMBERS AND SHEAF AREAS OF THE LONGISSIMUS DORSI MUSCLE
AND THEIR RELATIONSHIP TO CARCASS GRADE

Tenderness Panel
Carcass Member Member Member Member
Item Grade Average 1 2 3 4
r r r r r r

Tenderness by:
Panel, ave. .18** -- .68** .78** .81** .78**

Member 1 .11* --- --- .56** .53** .49**

Member 2 .1i2** --- -- .53** .47**

Member 3 .17** --- --- .55**

Member 4 .18** -

Tenderness by:
Shear ave. and -.17** -.58** -.54** -.41** -.46** -.45**

Shear area I and -.15** -.90** -.55** -.39** -.37** -.34**

Shear area 2 and -.10* -.44** -.41** -.36** -.36** -.28**

Shear area 3 and -.19** -.49** -.41** -.28** -.40** -.47**


**S gniflcant

* Significant


at the

at the


.01 level

.05 level


of probabi

of probabi


lity.

lity.











with a correlation coefficient of -.36; however, panel member 1 gave a

correlation coefficient of -.41. Thus panel members 2 and 3 apparently

are related to shear area 2 equally well, but panel member I showed a

slightly higher relationship to this area. Panel member 4 sampled the

same meat as shear area 3 and a highly significant correlation coefficient

of -.47 was noted between member 4 and shear area 3. Panel member 4

showed the highest correlation with this shear area, and thus suggests

that tenderness varied within the Longissimus dorsi muscle of beef and

that sampling tenderness from one location within the muscle is not a

sound practice. Perhaps the area showing the most pronounced tenderness

differences was shear area 3; however, shear area 1 gave a surprisingly

high correlation with the average panel tenderness score and this area

would be the preferred sampling area for shear if only one shear core was

to be taken. These data tend to indicate that a panel member's score is

more closely related to his respective shear area than to any other shear

area; except for panel member 4, the panel members scores were more closely

related to the average shear score than to any single shear area score.

The relationships between average panel tenderness and panel mem-

ber scores with shear values are given by partial regression coefficients

shown in Table 14. This table also gives the relationship between carcass

grade and shear evaluation with panel tenderness score held constant. It

may be noted that carcass grade Is the only variable that showed a signif-

icant partial regression coefficient with tenderness evaluation by Warner-

Bratzler shear technique, thus, the relationship between carcass grade and

shear is very pronounced even with panel tenderness evaluations held con-

stant. So close is the relationship between panel and shear that when




















TABLE 14

PARTIAL REGRESSION COEFFICIENTS SHOWING THE EFFECTS OF TENDERNESS
PANEL EVALUATIONS AND CARCASS GRADE ON
TENDERNESS SHEAR SCORE

Partial Regression Coefficients
Tenderness Panel
Dependent Carcass Member Member Mber ember Member
Variable Grade Average 1 2 3 4

Tenderness by
Shear ave. on -.130**l -2.6632 -.416 .530 .270 .299

Area I on -.139**1 -4.9912 -.269 .941 1.124 1.193

Area 2 on -.081*1 -1.8882 -.491 -.055 -.052 .493

Area 3 on -.172**l -.11592 -.527 .680 -.174 -.778


**Significant at the .01 level

* Significant at the .05 level


of probability.

of probability.


With all panel tenderness values held constant.


2With carcass grade and individual panel members held constant.











carcass grade and other panel scores are constant, only the panel observa-

tions that are highly correlated with that particular shear score show a

negative partial regression coefficient. It will be seen that average

panel score gave the following partial regression coefficients: -2.663,

-4.991, -1.888 and -1.159 for shear average and shear areas 1 through 3,

respectively. The relationship between average panel score and shear area

1 showed a correlating coefficient of -.90 in Table 13 and the relation-

ship between these two evaluations had the highest negative partial re-

gression coefficient. Panel member 1 had a high relationship to all shear

evaluations and, therefore, the highest negative partial regression coef-

ficients were found between panel member 1 and shear evaluations except

for shear area 3 In which panel member 4 was slightly more related to

shear than panel member I. The remaining panel members showed the highest

negative partial regression coefficients for their respective shear areas.

This suggests that there are tenderness variations within the Longissimus

dorsl muscle as reflected by the higher relationship between panel member

scores and their respective shear area evaluations.


Hide Thickness and Bone Breaking Strength as
Related to Tenderness

Collagen or connective tissue has been thought by early researchers

to have a marked Influence on beef tenderness. The animal's hide Is pri-

marily connective tissue and if the internal or intermuscular connective

tissue were proportional to the great amount found in the hide, perhaps

hide thickness would be an aid in determining or predicting tenderness.

Based on these assumptions, the thickness of hide was compared with ten-

derness of the meat as evaluated by tenderness panel and shear score. It










was felt that age might be affecting the thickness of hide as well as ten-

derness evaluations and therefore this variable was held constant. In

Table 15 it may be noted that age bears a pronounced relationship with

hide thickness and breaking strengths of metacarpal and metatarsal bones.

The thickness of the hide was highly significantly correlated with bone

breaking strengths. These correlations indicate that as the animal in-

creases in age, the thickness of hide and breaking strength of the meta-

carpal and metatarsal bones increases.

Carcass maturity is determined by the Federal meat grader by eval-

uating the hardness and other characteristics of bones in the carcass.

Thus if it is logical to assume that bone hardness of carcass maturity and

breaking strength are related, perhaps bone breaking strength could be used

to predict beef tenderness. Table 16 gives the average hide thickness,

breaking strength of metacarpal and metatarsal bones and tenderness evalu-

ations by panel and shear for each of the five percentages of Brahman

breeding. Hide thickness was greatest for breed group 3, slightly less

for group 2 and lowest for group 5. Bone breaking strength appears to

follow the same pattern; however, group 2 breaking strength was slightly

higher than group 3.

Table 17 shows the effect of hide thickness, age and bone breaking

strength on beef tenderness. It may be seen that the combined effects of

age, hide thickness and bone breaking strength showed a highly significant

effect on tenderness and also the effect of breeding indicated a highly

significant relationship with tenderness. Although the grouping of age,

hide thickness and bone breaking strength did not show the particular

variables that affected tenderness; however, it will be noted that in this



















TABLE 15

SIMPLE CORRELATIONS BETWEEN AGE, HIDE THICKNESS AND
BONE BREAKING STRENGTH


Breaking Strengths
Item Age Hide Thickness Metacarpal Metatarsal

Age --- .873** .780** .731**

Hide Thickness --- .923** .938**

Breaking Strength,
Metacarpal --- .985*

Breaking Strength,
Metatarsal ---


**Signlficant at .01 level of probability

















TABLE 16

AVERAGE HIDE THICKNESS, BONE BREAKING STRENGTH AND
TENDERNESS EVALUATIONS BY BREED GROUP

Percentage Brahman Breeding of Proqeny
1 2 3 4 5
(more than (less than
Item 75%) (75%) (50%) (25%) 25%)

Number of animals 38 43 36 23 25

Hide thickness, In. .193 .203 .208 .189 .170

Breaking strength,
Metacarpal, Ibs. 2107 2525 2461 2270 1747

Metatarsal, Ibs. 2669 3147 3078 2989 2283

Tenderness, panel1 3.66 3.36 3.58 4.37 4.19

Tenderness, shear2 11.73 12.83 11.48 10.01 10.77


ITenderness panel ranged from 1 to 6 with 1 being inedible; 2,
very tough; 3, slightly tough; 4, average tenderness; 5, above average;
6, excellent.


2Tenderness, shear lower scores Indicate more tender.

























TABLE 17

THE RELATIONSHIP OF BREEDING AND THE COMBINED EFFECTS OF AGE,
HIDE THICKNESS AND BONE BREAKING STRENGTHS ON
BEEF TENDERNESS


Mean Squares for Tenderness
Source df Panel Shear

Total 164 --- ----

BreedI 4 3.28** 37.85**

Residual 156 0.80 9.86


IBreed grouped into the five percentages of Brahman breeding.

**Significant at the .01 level of probability.











group of 165 animals, the effect of percentage of Brahman breeding showed

a highly significant effect on tenderness evaluations.

In Table 18 are shown the partial regression coefficients and the

significance of each variable on tenderness evaluations by panel and shear.

Although age again showed a highly significant effect on tenderness, the

partial regression coefficients are rather small. The partial regression

coefficient of -.045 indicates that an increase of 22.1 months over the

average age of 16.7 months would decrease the panel score from an average

of 3.75 to 2.75. Further, an increase in the average age from 16.7 months

to an average of 22.9 months, with all other conditions constant, would

increase the average shear score from 11.58 to 12.58. Hide thickness with

a partial regression coefficient of 5.26 was found to affect tenderness by

tenderness panel but no significant relationship was noted between hide

thickness and shear score. This effect was adjusted for percentage Brahman

breeding of progeny, age and breaking strength and yet was significant at

the .05 level of probability. The tenderness evaluation by tenderness

panel showed no significant relationship to breaking strength of the meta-

carpal bones, but a highly significant regression coefficient of -.0028

indicates a pronounced relationship between breaking strength of the meta-

carpal bones and tenderness evaluation by Warner-Bratzler shear apparatus.

The negative coefficient indicates that as bone breaking strength increases

the shear score decreases. Thus higher breaking strengths of the meta-

carpal bones indicated slightly more tender beef. No significant effect

of metatarsal bone breaking strength was noted on either methods of tender-

ness evaluation.



















TABLE 18

PARTIAL REGRESSION COEFFICIENTS OF AGE, HIDE THICKNESS AND BONE
BREAKING STRENGTH ON TENDERNESS EVALUATIONS

Tenderness


Item

Age

Hide thickness

Breaking strength,
Metacarpal

Hetatarsal

Breed group
Al


Pa el
bo

-.0453**

-5.2555*


.0004

-.00006


-.6462**

-.7000**

-.4987*

.0251


Shear
bo

.1605**

-.3233


-.0028**

.0007


2.1341*

2.8300**

1.6158

.4985


**Significant at the .01 level of probability.

* Significant at the .05 level of probability.


--











It seems that hide thickness and bone breaking strength have only

a slight relationship with tenderness and their use in predicting tender-

ness would be of little value.


Meatiness of the Beef Carcass

Muscling as Related to Various Measurements of the
Metacarpal and Metatarsal Bones

Certain characteristics of metacarpal and metatarsal bones have

been reported to bear a strong relationship with muscling or meatiness of

the carcass. Some physical measurements of these bones from 100 cattle

have been compared with areas of Longissimus dorsi muscle to determine the

relationship between bone characteristics and muscling.

Table 19 shows the average weight, length, weight/length ratio,

width and depth of metacarpal and metatarsal bones and the average area of

rib eye by breed group for 100 cattle slaughtered at the University Meat

Laboratory. It may be noted that breed groups 2 and 3 had heavier and

larger cannon bones than other breed groups. Average weights of meta-

carpal bones were 316, 341, 331, 263 and 275 grams for breed groups I

through 5, respectively, while metatarsal weights were 364, 409, 396, 372

and 320 grams for the five breed groups. Length of metacarpal bones was

greatest among the groups 1, 2 and 3 while bone width of metacarpals was

greatest among cattle with one-half or less Brahman breeding. Width and

depth of metatarsal bones was higher among cattle of groups 2, 3 and 4

than among groups 1 and 5.

In a Texas study by King (1959) it was noted that bone weight and

length showed a slight relationship to area of Longissimus dorsi, but when

the weight was divided by length to give a weight/length ratio, a more

pronounced relation to meatiness was found.













TABLE 19
AVERAGE PHYSICAL MEASUREMENTS OF METACARPAL AND METATARSAL BONES
CHARACTERISTICS AND LONGISSIMUS DORSI AREA BY BREED
GROUP FOR 100 ANIMALS

Percentage Brahman Breeding of Progeny
1 2 3 4 5
(more than (less than
Item 75%) (75%) (50%) (25%) 25%)

Number animals 26 25 18 14 17

Metacarpal
weight, gms 316 341 331 263 275

length, cm 21.0 21.8 21.6 20.3 19.1

weight/length 14.9 15.5 15.5 15.7 14.3

width, mm 31.5 31.6 34.0 34.2 32.5

depth, mm 22.8 24.2 24.2 23.9 22.6

Metatarsal
weight, gms 364 409 396 372 320

length, cm 23.9 24.9 24.2 23.0 21.6

weight/length 15.1 16.3 16.2 16.1 14.7

width, mm 28.1 29.9 30.0 29.9 28.1

depth, mm 27.2 29.1 29.5 28,8 27.1

Longissimus dorsi area,
square in. 6.62 7.32 8.83 7.41 6.02











To determine if the weight-length expression would show similar

results in this study, bone weight was divided by bone length. The

weight/length measurements were greatest for breed groups 2, 3 and 4 and

follows the same pattern as area of Longlsslmus dorsi. In all measure-

ments except metacarpal length and weight, breed groups 2, 3 and 4 were

greater than measurements of groups 1 and 5. Since these animals differed

markedly in size and weight, carcass length and carcass weight were held

constant. Table 19 reflects only unadjusted data and differences that

appear to exist may not be present when adjusted for carcass size and

weight.

The combined effects of bone characteristics, carcass size and

breeding are shown in Table 20. Percentage Brahman breeding showed to

significant relationship with area of Longissimus dorsi when carcass

length and weight were constant; however, the combined effects of bone

measurements and carcass size showed a significant relationship to meati-

ness as measured by Longisslmus dorsi area. It may be noted that carcass

weight had a highly significant effect on rib eye area and probably was

the major contributing factor in the effect of regression on rib eye area.

Table 21 gives the specific effect of each independent variable on

Longissimus dorsi area. Of the bone measurements, only the weight and

length of the metatarsal bone was significantly related to muscling of the

carcass and were significant only at the .05 level of probability. The

negative regression coefficient of -.117 for metatarsal weight on rib eye

area indicated that lighter weight bones had larger rib eye areas when

carcass weight and length were held constant. Conversely, the partial re-

gression coefficient for metatarsal bone length on rib eye area was





















TABLE 20

THE RELATIONSHIP OF COMBINED EFFECTS OF BONE CHARACTERISTICS AND
CARCASS SIZE AND THE EFFECT OF PERCENTAGE OF BRAHMAN
BREEDING OF PROGENY ON LONGISSIMUS DORSI AREA


Source df Sum of Squares Mean Squares

Total 99 301.80 ----

Breed 4 4.51 1.13

Residual 83 80.51 0.93


















TABLE 21

PARTIAL REGRESSION COEFFICIENTS OF CARCASS SIZE, BONE CHARACTERISTICS
AND PERCENTAGE OF BRAHMAN BREEDING OF PROGENY AND
CARCASS MUSCLING

Partial Regression Partial Regression
Coefficient of Coefficient of
Longissimus Dorsi Longlssimus Dorsi
Item Area on Item Area on

Carcass
length .037 Metatarsal
length 1.952*
Carcass
weight .006** wt./length 2.514

Metacarpal
weight .117 width -.152

length -2.003 depth 2.297

wt./length -2.129 Breed group

width .607 1 .696

depth -1.768 2 .975*

Metatarsal 3 .875*
weight -.117*
4 .424

**Significant at .01 level of probability.

Significant at .05 level of probability.

IA1l other Independent variables (percentage Brahman breeding,
carcass weight and length, metacarpal and metatarsal measurements) held
constant when determining relationship of a particular variable and
Longissimus dorsl area.










positive indicating that larger muscle area was associated with increased

length of metatarsal bones. The partial regression coefficient indicated

that an increase of .512 centimeters of metatarsal length with all other

measurements and carcass size constant would yield an increase of rib eye

area of one square inch over an area 7.02 square inches. King (1959)

found the weight, length and weight/length ratio to be reliable indicators

of muscling with partial correlations coefficients between metatarsal mea-

surements and rib eye are of .33, .32 and .33, respectively; however, even

though these coefficients were obtained holding carcass weight constant,

partial regression coefficients were not calculated and thus comparison be-

tween the Texas data and this study is not possible. It is of interest

that the weight/length ratio used in this study failed to show a signifi-

cant relationship to rib eye area and thus does not confirm the findings of

the Texas workers. The Texas studies by Wythe (1958), Orts (1959) and

King (1959) showed a slightly higher relationship between metatarsal char-

acteristics and rib eye area than between metacarpal measurements and rib

eye area. This was also true in these data and tend to substantiate the

Texas findings in this respect.


Relationship of Breeding to Muscling

The average rib eye area for all cattle was 7.02 square inches

while the average areas of rib eye were 6.62 and 6.02 square inches for

breed groups 1 and 5. Carcasses of breed groups 2, 3 and 4 had greater

rib eye areas with averages of 7.32, 8.83 and 7.41 square inches for breed

groups 2 through 4, respectively. When carcass length, carcass weight and

bone characteristics were held constant, percentage Brahman breeding showed











no significant gross relationship by regression analysis with size of rib

eye as given in Table 20; however, partial regression coefficients of .975

and .875 holding carcass size and bone characteristics constant as given

in Table 21 showed a significant difference in Longlssimus dorsi area be-

tween carcasses of breed groups 2 and 3 and carcasses of breed group 5.

The largest rib eye areas adjusted for other variables was found for car-

casses of group 2 while the smallest rib eye areas were produced by cattle

with the lowest percentage of Brahman breeding.

Kieffer et al. (1958) reported significant sire differences in rib

eye area with a heritability estimate of 56 per cent. An earlier study by

Clark (1954) indicated significant sire differences among Hereford cattle

for size of rib eye with an estimated heritability of 67 per cent. Sig-

nificant breed differences in rib eye area were reported by Cole et al.

(1958) in a study of dairy breeds, Angus, Hereford, Brahman and Brahman

cross breeds of cattle. Thus the results of this study indicating breed

differences in rib eye area are in agreement with previous findings.


Effect of Percentage Brahman Breeding on Slaughter
and Carcass Characteristics of Beef

Effect of Percentage of Brahman Breeding on
Certain Slaughter Characteristics

Weights of 222 animals were recorded at three times prior to

slaughter and weights were taken of items removed from carcasses during

the slaughter operation. Averages of these weights by breed group and

overall averages are given in Table 22. Since these are unweighted or un-

adjusted means, only obvious differences will be mentioned. No difference

was noted between breed groups for shrinkage between weights at the Range













TABLE 22

THE EFFECT OF PERCENTAGE OF BRAHMAN BREEDING OF PROGENY
ON SLAUGHTER CHARACTERISTICS OF BEEF


Percentage Brahman Breeding of Progeny
re 2 3 4 5 Total
(more than (less than or


I tem

No. animals

Liveweight at
Range Cattle
Stat., Ib

Slaughter weight,
lb

Chilled carcass
weight, Ib

Intransit shrink
and drift, per
cent

Dressing
percentage

Head weight, lb

Feet weight, Ib

Hide weight, Ib

Gastro-intestinal
tract and
contents, Ib

Pluck weight, lb

Liver weight, Ib


75%) (15%) (50%) (25%) 25%) Average


55


44


31


708.5 753.4 739.5 675.5


677.2 721.1 706.7 641.8


399.4 431.2 431.7



4.62 4.48 4.64


58.98

20.98

12.11

60.89



109.29

10.27

8.76


59.79

22.20

12.19

59.17



116.99

11.04

9.58


61.09

21.36

12.22

53.66



95.94

11.33

9.72


378.9



5.24


59.05

19.71

8.83

46.45



106.88

10.05

9.06


57


607.4


576.9


348.1



5.28


60.33

18.31

11.17

56.71



78.59

9.26

7.77


35


222


690.6


658.7


393.8



4.84


59.78

20.39

11.71

56.19



102.42

10.28

8.85











Cattle Station, Ona, and slaughter weights taken at Gainesville twenty-

four hours later. There was a slight trend for animals in groups 2, 3 and

4 to shrink less but this was not statistically significant. It may be

noted that dressing percentage was highest for breed group 4 with an aver-

age dressing percentage of 61.09 per cent while animals of breed group 2

had the lowest dressing percentage with an average of 58.98 per cent.

Though these differences appear rather wide, no significant difference in

dressing percentage was found between breed groups when slaughter weight

and carcass weight were held constant.

To determine the effect of breeding on slaughter characteristics

weights of the head, feet, hide, gastro-intestinal tract and contents,

pluck and liver were adjusted for both slaughter weight and chilled car-

cass weight. It may be noted in Table 23 that slaughter weight (regression)

and carcass weight showed a significant relationship to each item removed

during the slaughter operation except for carcass weight on weight of

feet. No significant gross effects of breed were found for weight of the

head or pluck weight. Mean squares for carcass weight were all lower than

mean squares for slaughter weight which Indicated that slaughter weight

bore a slightly greater relation to slaughter item than did carcass weight.

This was expected since the slaughter weight and slaughter items are a

part-whole relationship.

The weights of head expressed as a percentage of slaughter weight

as shown in Table 24 were 3.17, 3.10, 3.08, 3.02 and 3.07 per cent for

breed groups 1 through 5, respectively. The weight of head with slaughter

and carcass weights constant showed no significant gross breed effect, but

group 3 had significantly heavier head weights by partial regression co-


efficient than breed group 5.














TABLE 23

THE EFFECT OF SLAUGHTER WEIGHT, CARCASS WEIGHT AND BREEDING
ON ITEMS REMOVED DURING THE SLAUGHTER OPERATION


Mean Squares for Slaughter Items
Source df Head wt. Feet wt. Hide wt.

Total 221 --- --- ---

Breed 4 2.66 6.95** 1,527.05**

Carcass wt. I 272.53** 0.01 193.79**

Residual 214 2.75 1.09 47.56

Gastro-intestinal
Source df tract and contents wt. Pluck wt. Liver wt.

Total 221 --- --- ---

Breed 4 1,121.12** 2.01 2.87**

Carcass wt. I 148,403.03** 56.80** 16.67**

Residual 214 224.25 2.97 1.24


**Significant at the .01 level of probability.

















TABLE 24

THE EFFECT OF PERCENTAGE OF BRAHMAN BREEDING OF PROGENY ON PERCENTAGE
OF HEAD, FEET, HIDE, GASTRO-INTESTINAL TRACT AND CONTENTS,
PLUCK AND LIVER OF 222 CATTLE

Percentage Brahman Breeding of Progeny
I 2 3 4 5
(more than (less than
Item 75%) (75%) (50%) (25%) 25%)

Head wt., per cent 3.17 3.10 3.08* 3.02 3.07

Feet wt., per cent 1.94 1.79* 1.69* 1.73* 1.38

Hide wt., per cent 9.83** 8.99** 8.21** 7.59 7.24

Gastro-intestinal
tract and contents
wt., per cent 13.62** 16.14 16.22 13.47 16.65

Pluck wt., per cent 1.60 1.52 1.53 1.60 1.57

Liver wt., per cent 1.35* 1.29 1.33 1.38 1.41


**Signiflcantly different at .01 level of probability from breed
group 5.

Significantly different at .05 level of probability from breed
group 5.

lEach breed group compared with group 5 and with carcass and
slaughter weight held constant.











Significant breed differences in the weight of feet were noted be-

tween breed groups 2, 3 and 4 and 5 with the latter having lower weights

of feet. Breed group averages for feet were 1.94, 1.79, 1.69, 1.73 and

1.38 per cent, respectively, for breed groups 1 through 5. The greatest

breed differences in slaughter characteristics were noted with weight of

hide. Percentages of hide weight of 9.83, 8.99 and 8.21 per cent for

groups 1, 2 and 3 were significantly heavier than the 7.24 per cent average

for breed group 5. The 7.59 per cent weight of hide of group 4 was sig-

nificantly greater than hide weight of group 5.

It may be noted that percentage of gastro-intestlnal tract and

contents of breed group 1 was significantly lower than group 5 with aver-

ages of 13.62 and 16.65 per cent, respectively. These data tend to support

the findings of Butler et al. (1956) who noted in a study of Hereford and

Brahman X British crossbreds a difference of 2.73 per cent in dressing

percentage that could be explained almost entirely by lighter weights of

gastro-intestinal tract and contents from Brahman crossbreds. Carpenter

(1959) also noted highly significant differences in percentage of gastro-

intestinal tract and contents with decreased percentages associated with

increased percentages of Brahman breeding. Thus it seems that animals

with a high percentage of Brahman breeding tend to have lighter weights of

gastro-intestinal tract and contents which would increase dressing per-

centages of these animals compared with cattle of predominantly British

breeding.

No differences in weights of pluck (heart, lungs, esophogus and

trachea) were found between breed groups; however, animals of groups 2 and

3 appeared to have slightly lower percentages of pluck. Percentages of











pluck were 1.60, 1.52, 1.53, 1.60 and 1.57 per cent for breed groups I

through 5, respectively.

A significant difference in weights of liver were found between

breed groups 1 and 5 with the lower percentage, 1.35 per cent, from animals

of group 1. Liver percentages for groups 2 and 3 averaged lower than

livers of group 1, but when adjusted for slaughter and carcass weight, no

difference was found.

Differences between breed groups for Items removed during slaughter

were found in weights of head, feet, hide, gastro-Intestinal tract and

contents and liver while no breed differences were noted In weight of

pluck. Carpenter (1959) reported significant breed differences in weights

of feet, hide and gastro-intestinal tract and contents, but no differences

in weight of head, pluck or liver. Carpenter noted increased weights of

feet and hide and decreased weights of gastro-intestinal tract and contents

associated with Increased percentage of Brahman breeding. Results of this

study substantiate findings by Carpenter (1959) and Butler (1956) that

certain slaughter characteristics are definitely associated with breeding.


Effect of Brahman Breeding on Certain Carcass
Characteristics

Measurements were made on 125 carcasses of animals that varied in

their proportion of Brahman breeding and Table 25 shows average carcass

measurements by percentage Brahman breeding, carcass grades and marbling

scores. Average lengths of carcass were 39.4, 40.9, 42.6, 42.5 and 39.6

inches for breed groups I through 5, respectively; however no significant

breed differences as shown In Table 26 were found between breed groups.

To compensate for differences in grade and weight, carcass grade and















TABLE 25

THE EFFECT OF PERCENTAGE OF BRAHMAN BREEDING OF PROGENY ON
CERTAIN CARCASS CHARACTERISTICS OF 125 CATTLE

Percentage Brahman Breeding
I 2 3 4 5 Total
(more than (less than or
Item 75%) (7 50) (50%) 25%) (25%) Average

Number animals 37 24 20 24 20 125

One-half carcass
weight, lb 159.1 187.7 210.7 215.9 159.4 185.2

Carcass length,
In 39.4 40.9 42.6 42.5 39.6 40.8

Length of leg, In 27.7** 28.5** 28.5** 27.8 25.9 27.7

Circumference
of round, In 26.2* 28.2 29.9 30.0 27.6 28.1

Chuck thickness,
in 5.2* 5.4** 6.1* 6.2 5.5 5.6

Marbling degree 2.8 3.3* 4.5 4.9 3.8 3.7

Carcass grade2 12.1 12.9 14.3 14.9 13.2 13.3


**Significantly different at .01 level from group 5 with carcass
weight and grade held constant.

Significantly different at .05 level from group 5 with carcass
weight and grade held constant.

IMarbling degree coded from I to 12 with 1 being devoid; 2,
practically devoid.

2Carcass grade coded from 1 to 21 with I to 3 being Canner; 4 to
6, Cutter.




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