Effect of boron supplementation of practical corn-soybean meal diets for poultry

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Effect of boron supplementation of practical corn-soybean meal diets for poultry
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Rossi, Alfredo F., 1956-
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Thesis (Ph. D.)--University of Florida, 1990.
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Includes bibliographical references (leaves 85-90).
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by Alfredo F. Rossi.
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EFFECT OF BORON SUPPLEMENTATION OF
PRACTICAL CORN-SOYBEAN MEAL DIETS
FOR POULTRY


















By

ALFREDO F. ROSSI


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

UNIVERSITY OF FLORIDA


1990


UNIVERSITY OF FLORIDA LIBRARIES


































To Jennifer Camille.














ACKNOWLEDGEMENTS


I would like to express my most sincere appreciation to

Dr. Richard D. Miles for his constant interest, support, and

guidance during the research work and the writing of this

dissertation.

I extend my appreciation to the members of my advisory

committee, Dr. Robert H. Harms, Dr. Gary D. Butcher, and Dr.

James R. Simpson, and to Dr. Steve R. Lee from the University

of Arkansas, for their comments and technical advisement

throughout the development of the research.

I am indebted to the Poultry Science Department for

granting me a research assistantship and for providing

facilities and equipment for conducting this research.

I also wish to thank Thornton Labs., Inc. of Tampa,

Florida, and the Chemistry Department for their permission to

use their instruments for boron analysis; Gold Kist Poultry,

Inc. of Live Oak, Florida for donating the broiler chicks used

in one experiment; and the Department of Animal Science for

permission to use a fluorometer.

Special thanks are extended also to Dr. Salim Bootwalla,

Mr. David Eberst, Mr. Gary Smith, Mr. Alan Eldred, and Mrs.

Linda Flunker from the Poultry Science Department; Dr. Myron

Chung and Dr. Sudeep Kundu from Statistics; to Mrs. Pam Miles

iii








from the Animal Science Nutrition Laboratory; to Dr. Fran

Saunders and Ms. Melody Hartnup from Chemistry; and to Ms.

Marcia Harvey, Mr. Wayne Rosbach, and Mr. Rajesh Patel from

Thornton Labs., Inc.

Sincere gratitude is extended to my unforgettable good

friends, the professors, laboratory technicians, farm crew,

and graduate students of the Poultry Science Department for

help received during the implementation of the research.

My heartfelt feelings of appreciation and love are

expressed to my wife Eileen, our daughter Jennifer, and the

rest of my family for their moral support.















TABLE OF CONTENTS


ACKNOWLEDGEMENTS . .

LIST OF TABLES . .

LIST OF FIGURES . .

KEY TO SYMBOLS . .

Abstract . .

CHAPTER 1
INTRODUCTION . .
Boron as an Essential Element .
Boron Distribution .
Requirements of Boron for Poultry
Boron Toxicity . .


CHAPTER 2
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON BROILERS . . .
Introduction . . .
Materials and Methods . .
Experiment 1 . . .
Experiment 2 . . .
Results and discussion . .

CHAPTER 3
EFFECTS OF FEEDING THREE DIFFERENT DIETARY
BORON SOURCES ON BROILERS . .
Introduction . . .
Materials and Methods . .
Results and discussion . .

CHAPTER 4
THE INTERACTION OF BORON WITH CALCIUM, PHOSPHORUS,
AND VITAMIN D3 IN BROILERS . .
Introduction . . .
Materials and Methods . .
Results and discussion . .


iii


. vii

x

. xi

. xii


""'
"'








CHAPTER 5
EFFECTS OF SALT (NACL) WITHDRAWAL AND DIETARY BORON
SUPPLEMENTATION ON THE PERFORMANCE AND BONE
DEVELOPMENT OF CHICKS . 41
Introduction . . 41
Materials and Methods . .. 42
Results and discussion . .. 44

CHAPTER 6
DIETARY BORON AND RIBOFLAVIN SUPPLEMENTATION
FOR BROILERS FED TO 49 DAYS OF AGE . 49
Introduction . .. 49
Materials and Methods . .. 51
Results and discussion . 55

CHAPTER 7
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON LAYING HENS .. . ... 62
Introduction . . .. 62
Materials and Methods .. . 63
Results and discussion. . .. 65

CHAPTER 8
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON BROILER BREEDERS . .. .68
Introduction . ... 68
Materials and Methods . .. 69
Experiment 1 . . .. 69
Experiment 2 . . 70
Results and discussion . .. 71

CHAPTER 9
SUMMARY. . . 77

GLOSSARY . .. 83

REFERENCE LIST . . .. 85

BIOGRAPHICAL SKETCH. ... . ... 91













LIST OF TABLES


Table 1-1. Suggested trace mineral supplements to
chemically defined diets . 6

Table 2-1. Composition of the basal diet used in
Experiment 1 and Experiment 2 ... 14

Table 2-2. Performance of broiler chicks to 21 days of
age fed various levels of supplemental boron in a
practical corn-soybean meal diet (Experiment 1) 17

Table 2-3. Measurements of the fat-free left tibiae of
broiler chicks 21 days of age fed various levels of
supplemental boron in a practical corn-soybean meal
diet (Experiment 1) . ... 18

Table 2-4. Performance of broiler chicks to 21 days of
age fed various levels of supplemental boron in a
practical corn-soybean meal diet (Experiment 2) 19

Table 2-5. Measurements of the fat-free left tibiae of
broiler chicks 21 days of age fed various levels of
supplemental boron in a practical corn-soybean meal
diet (Experiment 2) . ... 21

Table 2-6. Body weight, small intestine weight, and
small intestine to body weight ratio in broiler
chicks 22 days of age fed various levels of
supplemental boron in a practical corn-soybean meal
diet (Experiment 2) . ... 23

Table 2-7. Boron concentration in breast muscle
pectoraliss major) and in liver of broiler chicks
21 days of age fed various levels of supplemental
boron in a practical corn-soybean meal diet
(Experiment 2) . . 24

Table 3-1. Composition of the basal diet used in the
experiment . . .. .. 27

Table 3-2. Performance of broiler chicks to 21 days of
age fed three levels and three sources of
supplemental boron in a practical corn-soybean meal
diet . . 29


vii








Table 3-3. Measurements of the fat-free left tibiae and
cumulative mortality of broiler chicks 21 days of
age fed three levels and three sources of
supplemental boron in a practical corn-soybean meal
diet . .. 30

Table 4-1. Composition of the basal diet used in the
experiment . ...... 34

Table 4-2. Performance of broiler chicks to 21 days of
age fed different levels of calcium (Ca) and non-
phytate phosphorus (P), and supplemented with
different amounts of boron (B) and Vit. D3 (D3) in
a corn-soybean meal diet . .. 36

Table 4-3. Fat-free tibia weight and ash, and tibial
dyschondroplasia score of broiler chicks 21 days of
age fed different levels of calcium (Ca) and non-
phytate phosphorus (P), and supplemented with
different amounts of boron (B) and Vit. D3 (D3) in
a corn-soybean meal diet . .. 38

Table 5-1. Composition of the basal diet used in the
experiment . . 43

Table 5-2. Performance of male broiler chicks to 7, 14,
and 21 days of age fed a corn-soybean meal diet
with (+) or without (-) .40% salt supplementation
for the first seven days of age combined with the
addition of 0 or 20 ppm boron as boric acid 45

Table 5-3. Fat-free tibia weight and ash, and tibial
dyschondroplasia score of broiler chicks at 7, 14,
and 21 days of age fed a corn-soybean meal diet
with (+) or without (-) .40% salt supplementation
for the first seven days of age combined with the
addition of 0 or 20 ppm boron as boric acid 48

Table 6-1. Composition of the starter (0-3 wk) and
finisher (4-7 wk) basal diets used in the
experiment . . .. 52

Table 6-2. Costs and prices used for the price-
sensitivity analysis of broiler chicks grown to 49
days of age and fed a practical corn-soybean meal
diet supplemented with different amounts of
riboflavin and boron . .. 54

Table 6-3. Performance of broiler chicks to 21 and 49
days of age fed a corn-soybean meal diet
supplemented with different amounts of riboflavin
(Rib.) and boron . ... .56


viii







Table 6-4. Fat-free tibia weight, and ash of broiler
chicks 49 days of age fed a corn-soybean meal
supplemented with different amounts of riboflavin
and boron .. . 58

Table 6-5. Economic performance of broiler chicks to 49
days of age fed a corn-soybean meal diet
supplemented with different amounts of riboflavin
(Rib.) and boron . ... .59

Table 7-1. Composition of the basal diet used in the
experiment . .... 64

Table 7-2. Performance of laying hens fed a corn-soybean
meal diet supplemented with various amounts of
boron . . ... 66

Table 8-1. Performance of broiler breeder females fed a
corn-soybean meal diet supplemented with 0
(control) or 250 ppm boron supplied as either boric
acid or borax (Experiment 1) . ... 72

Table 8-2. Characteristics of eggs from broiler breeder
females fed a corn-soybean meal diet supplemented
with 0 (control) or 250 ppm boron supplied as
either boric acid or borax (Experiment 1) 74

Table 8-3. Performance of broiler breeder males fed a
corn-soybean meal diet supplemented with 0
(control) or 250 ppm boron supplied as either boric
acid or borax (Experiment 2) . ... 75














LIST OF FIGURES


Figure 6-1. Effect of boron supplementation on adjusted
profits from broiler production (average profit
scenario) . . .. 60

Figure 6-2. Effect of boron supplementation on adjusted
profits from broiler production (best profit
scenario). . . .. 61














KEY TO SYMBOLS

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$ dollars

< less than

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Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

EFFECTS OF BORON SUPPLEMENTATION OF
PRACTICAL CORN-SOYBEAN MEAL DIETS
FOR POULTRY

By

Alfredo F. Rossi

August, 1990

Chairperson: Richard D. Miles
Major Department: Animal Science

Nine experiments were conducted to study the effects of

boron supplementation of practical corn-soybean meal diets for

poultry.

Five experiments were conducted with broiler chicks grown

to 21 days in batteries. Male body weight was highest when a

basal diet was supplemented with 5 ppm boron. Body weight and

feed intake were depressed when diets were supplemented with

more than 120, but especially over 240 ppm boron. The best

feed conversion was achieved when boron was supplemented at

120 ppm. An index of efficiency of mineral utilization

improved with the addition of boron to the diets. Percent

tibia ash was significantly higher only when boron was

supplemented at the highest level (300 ppm). The correlation

between boron supplementation and liver or breast muscle

contents of boron was high.


xii








One experiment was conducted with broilers grown to 49

days on litter. The addition of riboflavin did not alleviate

the body weight depression which resulted from boron

supplementation. However, when 17.6 ppm riboflavin was added

in combination with 320 ppm boron, at 49 days of age feed

consumption was the lowest and feed conversion was the best of

all other treatment groups. Boron supplementation of 20 or 80

ppm resulted in higher profits as compared with boron

supplementation of either 0 or 320 ppm.

Another experiment was conducted to study the effects of

supplementing laying hen diets with various amounts of boron.

Addition of 40 or 80 ppm boron did not affect any variable

studied. During the second 28-day period egg specific gravity

and calculated shell weight were significantly lower in birds

fed 20 ppm boron compared to the group fed no boron

supplementation.

Two experiments were conducted to study the effects of

supplementing broiler breeder diets with 250 ppm boron

supplied as either boric acid or as borax. Females fed boron

had numerically lower fertility and significantly lower

hatchability in each of the three fertility trials conducted.

Males fed boron produced three times more damaged spermatozoal

cells as compared with the control birds.


xiii














CHAPTER 1
INTRODUCTION


Boron as an Essential Element


Boron has long been recognized as essential for plants.

However, it was not until the last decade that its importance

for animals was recognized as well. Boric acid and borax were

used in swedes' by Honningstad (1935) to reverse a boron

deficiency called "dropsy." Exploratory trials made by the

Oregon Agricultural Experiment Station (1941) showed many of

the older, more sandy, and some of the leachy irrigated soils

to be in need of boron. These studies concluded that the

application of 30 pounds of borax an acre increased the

chlorophyll as much as 50% and the carotene content of alfalfa

30% according to chemical determinations.

The demonstration that boron is an essential element in

the nutrition of plants, and data showing its occurrence in

animal tissues, have served as stimuli for investigators to

ascertain whether this element is essential in the metabolism

of animals. Attempts made by Orent-Keiles (1940) and by Teresi

et al. (1944) to induce a boron deficiency in rats failed,

although the control diets apparently contained only .16 ppm.



1 A root vegetable.








2

Later, Skinner and McHargue (1945) reported that rats

consuming a low-boron (.45 ppm), low-potassium (51 ppm) diet,

supplemented with either boric acid or borax in variable

amounts from 100 to 1,000 ppm boron, survived longer and

contained more liver glycogen and body fat. Six animals which

received the high-boron diets were living after all of the 54

control animals had died. Those findings were not confirmed by

Follis (1947) when he added 2,200 ppm boron to low potassium

(< 100 ppm) diets. However, the boron content in the control

diet was unknown.

After those reports the study of boron as a possible

nutrient for animals was neglected until the 1980s, when Hunt

and Nielsen (1982) supplemented a purified diet containing

only .28 ppm boron with 3 ppm boron and either adequate or

deficient amounts of Vit. D3. The aforementioned authors found

an interrelationship between boron and Vit. D3. Boron

supplementation improved chick body weight at 32 days of age

by 11% when the Vit. D3 content of the diet was adequate

(2,500 IU/Kg) and by 38% when the Vit. D3 was deficient (125

IU/Kg). Hunt and Nielsen (1986, 1987) reported that in a

vitamin D3-deficient diet, dietary boron increased chick body

weight, lowered plasma glucose, improved the grossly deformed

tibial epiphysial plate, and that the interactions between

boron and molybdenum and between boron and magnesium affected

hemoglobin and plasma alkaline phosphatase. Nielsen (1986a)

also found that dietary boron affected the response of rats to








3

magnesium deprivation and high dietary aluminum, and that this

response was influenced by methionine status.

In postmenopausal women, boron supplementation (3 mg/day)

to diets low in boron (.25 mg/day) elevated the serum

concentrations of estradiol and testosterone (Nielsen et al.,

1987). According to Nielsen and Hunt (1987) these steroid

hormones are so important for maintaining bone and calcium

status that estrogen replacement therapy is currently the only

proven treatment for osteoporosis. These authors also reported

that women receiving the boron treatment lost one-third less

magnesium and 40% less calcium through urinary excretion and

retained an average of 52 mg more calcium per day.

In sheep, boron supplementation of 75 or 200 mg/day to a

daily consumption of 30 mg boron increased calcium

digestibility and calcium retention at each level of boron

addition (Brown et al., 1988).

In a field study with heifers, Green and Weeth (1977)

found that urinary excretion of phosphate was decreased and

plasma phosphate was increased by adding 150 and 300 ppm boron

to the water.

One of the objectives of this research was to determine

the influence of dietary boron on variables dependent on

calcium metabolism in the bird such as bone characteristics

and egg shell quality.










Boron Distribution


Boron occurs naturally in the form of borax, borates,

boric acid, and certain borosilicate minerals, such as

formaline. The principal source of boron in the U.S.A. is

marine evaporative deposits found in the south-west. Boron is

present in the oceans to the extent of about 4.7 mg/l as a

world-wide average (Carriker et al., 1976).

Meat or fish are poorer sources of boron compared with

foods of plant origin; fruits, nuts, and legumes being

generally richer in boron than grasses. An extensive study of

more than 200 Finnish foods as cited by Nielsen (1986b),

concluded that the average boron content in ppm of dry weight

was .16 for meat, .36 for fish, .92 for cereals, 1.1 for dairy

products, and 13 for vegetable foods.

An interesting observation regarding the relationship

between boron distribution and human health is that

vegetarians have a lower than average incidence of

osteoporosis. However, eskimos who eat almost no vegetables

have a very high incidence of osteoporosis (Nielsen and Hunt,

1987).

Boron compounds are commonly used as water treatments,

detergents, algicides, insecticides, wood preservatives, and

fertilizers (Carriker et al., 1976). Additional sources of

boron in commercial poultry production are calcium phosphates

(Shuler, 1988, Grand Forks Human Nutrition Research Center,

Grand Forks, ND, personal communication), litter treatments








5

used for control of beetles (Lee, 1989), and wood shavings

which may contain boron as it is often used as a wood

preservative.

Another objective of this research was to determine the

influence of dietary boron concentration on tissue boron

accumulation.


Requirements of Boron for Poultry


The minimum amounts of boron required by the different

categories of poultry have not been determined. In searching

the literature no experiment with poultry has been found

involving the addition of increasing increments of boron to a

diet known to be deficient in the mineral. However, 3 ppm

boron supplementation was found to improve chick body weight

when the control birds were fed basal diets containing .28 ppm

boron (Hunt and Nielsen, 1982) or .85 ppm (Hunt and Nielsen,

1986). Therefore, the requirements of chicks could be more

than .85 ppm.

The National Research Council (1984) recommends a minimum

of 2 ppm for chicks when fed purified diets (Table 1-1).

However, no reference was found in the aforementioned

publication to support this recommendation.

Elliot and Edwards (1990) conducted an experiment with a

factorial arrange of treatments involving the addition of

different levels of calcium, Vit. D3, and boron, to a purified

basal diet for broilers. These authors found that the addition











Table 1-1. Suggested trace mineral supplements
to chemically defined diets.

Element ppm


Boron 2
Chromium 3
Molybdenum 1
Nickel 0.1
Silicon 250
Tin 3
Vanadium 0.2
Fluorine 20
Inorganic sulfate *


There may be a response to inorganic sulfate
if the diet is low in cystine.

Source: National Research Council (1984).


of 3 ppm boron tended to increase bone ash (P = .06), and that

there was a significant interaction between boron and Vit. D3

which affected weight gain.

Another objective of this research was to determine if

supplementing boron to a practical corn-soybean meal diet

would enhance poultry performance.


Boron Toxicity


Sherwood (1959) studied the effects of the addition of a

borate-based larvicidal drug (Polybor 3) to laying hen diets

at levels of 0, 2, 3, and 6 pounds per ton, i.e. 0, 210, 315,

and 629 ppm boron2, respectively. The level of 629 ppm boron



2 Calculated from dosage and boron content of Polybor 3:
disodium octaborate tetraydrate (20.97% boron).








7

resulted in a complete inhibition of viable fly larvae but egg

production of hens was markedly poorer. While at the 315 ppm

boron level about half of the expected larvae developed and

egg production was slightly lower than the control birds.

Other production variables were not reported by the author.

In a two-year study with rats and dogs Weir and Fisher

(1972) found no adverse effects of 117 and 350 ppm boron in

the diet. However, after two months of feeding the diets

containing 1,170 ppm of boron, rats exhibited coarse hair

coats, scaly tails, a hunched position, swelling and

desquamation of their paw pads, abnormally long toenails,

bloody discharge from the eyes, and depressed hemoglobin and

hematocrit. After 38 weeks, dogs fed 1,170 ppm boron exhibited

reversible testicular degeneration and cessation of

spermatogenesis.

In a field study with heifers, Green and Weeth (1977)

concluded that the safe concentration of boron in drinking

water was probably between 40 and 150 ppm. Treatments of 150

and 300 ppm boron in the water were not acutely toxic but

resulted in lower hay consumption accompanied by a loss of

body weight. However, water consumption and urine output were

not affected and urinary excretion of phosphate was decreased

by the boron-water.

Frost (1942) showed that stable aqueous solutions of at

least 25 times the natural solubility of riboflavin could be

prepared in the lab by addition of borates. This led to the








8

conclusion of the existence of water-soluble riboflavin-boron

complexes.

Roe et al. (1972) found that diets containing .8% boric

acid (1,400 ppm boron3) severely impaired growth of White

Leghorn chicks when supplemented to diets containing 7 ppm

riboflavin. When the chicks received 14 ppm riboflavin their

body weight was significantly improved. Further improvement in

growth was not obtained by increasing the riboflavin levels up

to 28 ppm (after 21 days on the latter diet their body weight

was about half of the control group fed no supplemental

boron). By studying the urinary excretion of radioactively

marked riboflavin, Roe et al. (1972) demonstrated in rats and

guinea pigs that riboflavin depletion can be induced by

borate. These authors proposed that the mode of action of

borates on riboflavin excretion via the kidney was by

detaching this vitamin from binding sites on serum proteins,

through formation of flavin-borate complexes.

Riboflavin deficiency signs in dead embryos (Lee, 1989),

and increased weight of the thyroid gland (Lee and Emmel,

1990) were found after application of borate insecticides to

the litter of their parent flock. This research seems to

confirm that boron toxicity causes riboflavin depletion.

Landauer (1952) found that the injection of boric acid in

the yolk of developing embryos led to various malformations.



3 Calculated from dosage and boron content of boric acid
(17.5% boron).







9

Riboflavin dissolved in boric acid greatly reduced the

teratogenic properties of boric acid. The livers of boric

acid-treated and morphologically abnormal embryos were

deficient in riboflavin. After these findings the author

assumed that the morphogenetic effects of boric acid were

mediated via complexation of riboflavin-containing enzymes.

However, Landauer (1953) found that other polyhydroxy

compounds besides riboflavin (D-ribose, pyridoxine

hydrochloride, D-sorbitol hydrate) also completed with boric

acid and reduced its teratogenic properties. Therefore, the

author concluded that boric acid interferes with normal

development by complex formation in ovo with polyhydroxy

compounds, thereby producing signs resembling riboflavin

deficiency.

Other objectives of this research were to determine if

the addition of different amounts of boron to practical corn-

soybean meal diets for poultry would result in toxicity

as well as to determine whether or not additional riboflavin

would counteract the possible toxic effects of boron.













CHAPTER 2
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON BROILERS


Introduction


The National Research Council (1984) suggested that the

trace mineral supplements to chemically defined diets for

poultry should contain at least 2 ppm of boron. However, no

reference was found in the aforementioned publication to

accompany this recommendation.

No data with poultry have been found in the literature

involving the addition of increasing amounts of boron to a

diet known to be deficient in the mineral. Although the

minimum amount of boron required by the different categories

of poultry has not yet been determined, there has been some

research work indicating a favorable response of broilers to

boron supplementation of purified diets. Hunt and Nielsen

(1982) supplemented a purified diet containing only .28 ppm

boron with 3 ppm boron and either adequate or deficient

amounts of Vit. D3. These authors found an interrelationship

between boron and Vit. D3. Boron supplementation improved

chick body weight at 32 days of age by 11% when the Vit. D,

content of the diet was adequate (2,500 IU/Kg) and by 38% when

the Vit. D3 was deficient (125 IU/Kg). Hunt and Nielsen (1986)








11

reported that after four weeks of boron deprivation chick

growth was depressed, plasma glucose was elevated, and brain

weight to body weight ratio was increased. These authors found

that an interaction between boron and magnesium affected

hemoglobin and plasma alkaline phosphatase. Also, an

interaction between boron and molybdenum affected the heart

weight to body weight and the liver weight to body weight

ratios. Elliot and Edwards (1990) used a factorial arrangement

of treatments involving the addition of calcium, Vit. D3, and

boron to purified diets for broilers. These authors found that

the addition of 3 ppm boron tended to increase bone ash (P =

.06), and that there was a significant interaction between

boron and Vit. D3 on weight gain.

Supplementation of broiler diets with boron could be

detrimental as in the experiment of Roe et al. (1972), who

found that weight gain was less than half that of the control

birds after 24 days of feeding chicks with the addition of .8%

boric acid (1,400 ppm boron1).

Practical diets for broilers are formulated using a

variety of natural feedstuffs which contain variable amounts

of boron. However, because of economic reasons, soybean meal

is commonly added as a protein concentrate, usually at a rate

of more than 20% of the broiler diets.





1 Calculated from dosage and boron contents of boric acid
(17.5% boron).








12

Boron is rarely analyzed for in commercial poultry

production. According to an extensive study of Finnish foods

cited by Nielsen (1986b), soybean meal contains an average of

28 ppm boron (wet basis), while cereals contain about .92 ppm

(dry basis). The boron content of soybean meal alone would

account for more than 5.6 ppm boron in a typical corn-soybean

meal practical diet. Additional sources of boron in commercial

poultry production are calcium phosphates (Shuler, 1988, Grand

Forks Human Nutrition Research Center, Grand Forks, ND,

personal communication), litter treatments (Lee, 1990), and

wood shavings (Carriker et al., 1976).

The present experiments were conducted with the objective

of determining if boron is required by broiler chicks in

amounts above those furnished by the ingredients of practical

corn-soybean meal diets as well as to determine if the

addition of moderate amounts of boron (up to 300 ppm) would be

detrimental to broiler performance.


Materials and Methods


Two experiments were conducted consisting of the addition

of different amounts of boron supplied as boric acid2 to the

diets, using a total of 432 day-old broiler chicks.

The birds were feather-sexed at one day of age, and

weighed in groups of three birds per sex. Six birds per pen,

three male and three female chicks, were assigned at random to


2 Reagent grade, Fisher Scientific, Fair Lawn, NJ.







13

each replicate, and placed in Petersime battery brooders3 with

raised wire floors for 21 and 22 days in Experiment 1 and

Experiment 2, respectively.

Experiment 1

One hundred forty-four Cobb x Cobb broiler chicks were

assigned to five dietary treatments: 0, 5, 40, 80, and 120 ppm

supplemental boron with five replicates per treatment, except

for the control group which had only four replicates.

The ambient temperature was provided and thermostatically

controlled by a central heating system and wall fans. This

temperature was set at 320C the first day of the experiment

and diminished 10C every third day. Feed and tap water were

offered ad libitum and lighting was continuous throughout the

experimental period.

The composition of the corn-soybean meal based diet

(Table 2-1) was formulated to meet or exceed the requirements

of growing chicks (National Research Council, 1984). A sample

of the basal diet used in this experiment was sent to a

commercial laboratory4 to be analyzed for boron content by ICP

Atomic Emission Spectrometry Analysis.

At 21 days of age feed consumption was determined and all

birds were individually weighed. Then, one male was randomly

chosen and sacrificed from each replicate. The left leg was



3 Petersime Incubator Co., Gettysburg, OH.

4 Hazelton Laboratories America, Inc., Chemical & Biomedical
Sciences Division, Madison, WI.








14
Table 2-1. Composition of the basal diet used in Experiment 1
and Experiment 2

%

Ground yellow corn 55.83
Dehulled soybean meal (48.5% C.P.) 37.29
Corn oil 2.50
Dicalcium phosphate (22.0% Ca, 18.5% P) 1.72
Ground limestone 1.01
Microingredients* .50
Iodized salt .40
DL-Methionine (98%) .25
Variables** .50

SSupplied per kilogram of diet: 6,600 IU vitamin A, 2,200 IU
vitamin D3, 2.2 mg menadione dimethylpyrimidinol bisulfite,
4.4 mg riboflavin, 13.2 mg pantothenic acid, 39.6 mg niacin,
499 mg choline chloride, .022 mg vitamin B12, 125 mg
ethoxyquin, 60 mg manganese, 50 mg iron, 6 mg copper, .198 mg
cobalt, 1.1 mg iodine, and 35 mg zinc.
SContained variable amounts of washed builders' sand and
boric acid according to the different treatments.



removed and frozen in a plastic bag for later analysis. At a

later date, the legs were thawed, boiled for five minutes, and

the tibiae were excised and defleshed. The proximal cartilages

of the tibias were removed. The bones were air dried at room

temperature for 48 hours in an air-conditioned room, and then

the fat content was removed using petroleum ether as a

solvent. The force required to break the tibiae, was measured

on a Texture Test System press5 by the procedure of Rowland

et al. (1967). The tibia fragments were ashed according to the

procedure outlined by the Association of Official Agricultural

Chemists (1965).


5 Model # TP-1, Food Technology Corporation, Rockville, MD.








15

Average calcium consumption was calculated from the pen

feed consumption and the calcium content of the feed

ingredients (National Research Council, 1984). An index was

developed to quantify the relationship between calcium

consumption and mineral deposition. This index was calculated

as grams of ash in the fat-free left tibia bone divided by the

calculated total amount of calcium consumed based on the pen

average.

Experiment 2

Two hundred eighty-eight Ross x Ross broiler chicks were

assigned to six dietary treatments: 0, 60, 120, 180, 240, and

300 ppm supplemental boron with eight replicates per

treatment.

The composition of the basal diet and the procedures used

in this experiment were essentially the same as in Experiment

1 with the following differences:

A sample of the basal diet used in this experiment was

taken and frozen in a plastic container. At 21 days of age, in

addition to the left leg, the liver, and left pectoralis major

muscle, were also excised and frozen in plastic bags for boron

analysis. At a later date, the feed, liver, and muscle samples

were thawed, weighed, freeze-dried, and then reweighed to

measure moisture loss. The samples were minced in small pieces

with a scalpel and about 1.5 g of each sample was weighed.

Samples were microwave-digested with acids (HNO3 and HC1),

high pressure (up to 7.3 Kg/cm2), and temperature (up to







16

2000C), in 120 ml-teflon vessels as described in the Diet

Microwave Digestion Procedure (Schelkop, 1988). The samples

were then filtered, brought up to 25 ml with deionized water,

and analyzed for boron content using an ICP instrument6. The

emission spectroscopy of each sample was analyzed with five

replicates, at a wavelength of 249.757 nm, and using a

monochrometer reading height of 7 mm.

At 22 days of age, one male and one female were randomly

chosen and killed by cervical dislocation from each of the

eight replicates of the control and of the 60 ppm boron-

supplementation-group. The birds were then weighed and the

entire small intestine was removed. The weight of the small

intestine was recorded after removing the contents by careful

hand stripping along the length of the tract.

Data were subjected to analysis of variance, and linear

regression (SAS, 1985). Significant differences were

determined by Duncan's multiple range test and the Student t

test (Snedecor and Cochran, 1974).


Results and discussion


The basal diet used in Experiment 1 contained 9.4 ppm

boron (by analysis). Boron concentration of the different

municipal water reservoirs of Florida were analyzed by




6 Perkin-Elmer Plasma II Emission Spectrometer,
The Perkin-Elmer Corporation, Lake Mary, FL.








17

Carriker et al. (1976) and found to be always less than .1

ppm.

Results of Experiment 1 indicate that male birds fed 5

ppm boron had significantly higher body weight than the

control birds (Table 2-2). However, no significant differences

among the treatments were found for female or average body

weight of both sexes.


Table 2-2. Performance of broiler chicks to 21 days of age
fed various levels of supplemental boron in a practical corn-
soybean meal diet (Experiment 1)

Sup. Body weight Feed Feed Mortality
boron Males Females Average intake conversion
(ppm) (g) (g) (g) (g) (g/g') (%)


0 586 b 564 575 850 1.48 a 0
5 647 a 579 613 884 1.44 ab 0
40 637 ab 568 603 880 1.46 ab 0
80 612 ab 547 579 846 1.46 ab 0
120 612 ab 553 582 799 1.37 b 3.3

Pooled
SEM 17.9 15.8 12.8 29.5 .032 1.3


Grams of feed intake per grams of average body weight.

ab Values within columns followed by different letters are
significantly different (P<.05).



While maximum male body weight may have been obtained by

the addition of 5 ppm boron to the diets, birds fed 120 ppm

boron had the best feed conversion (Table 2-2). However, under

the experimental conditions it was not possible to determine








18

whether male feed conversion was different than the female

feed conversion.

Birds fed diets with the addition of 5 ppm boron had

significantly higher tibia breaking load, tibia weight, and

grams of tibia ash, as compared to the control birds (Table 2-

3). However, tibia weight alone could account for the

differences in grams of tibia ash, and possibly for the

differences in breaking load, since no significant differences

were found for percent tibia ash.



Table 2-3. Measurements of the fat-free left tibiae of broiler
chicks 21 days of age fed various levels of supplemental boron
in a practical corn-soybean meal diet (Experiment 1)

Sup. Breaking Weight Ash Ash Index
boron load
(ppm) (Kg) (g) (%) (g) (g/g*)


0 9.1 b 1.52 b 45.8 .696 b .094 b
5 11.2 a 1.77 a 46.5 .825 a .107 ab
40 10.1 ab 1.66 ab 46.7 .775 ab .101 ab
80 9.7 ab 1.68 ab 47.0 .790 ab .107 ab
120 9.7 ab 1.64 ab 47.1 .773 ab .111 a

Pooled
SEM .49 .075 .54 .0369 .0049


Grams of tibia ash per calculated total grams of
calcium consumption.

ab Values within columns followed by different letters are
significantly different (P<.05).



Calculated total grams of calcium consumption to 21 days

were 7.44, 7.74, 7.70, 7.40, and 6.99 for birds fed diets with

the addition of 0, 5, 40, 80, and 120 ppm boron, respectively.










The "grams of ash in the fat-free left tibia bone per

calculated total grams of calcium consumption" index was

significantly higher for the birds fed diets with the addition

of 120 ppm of boron as compared with the control birds (Table

2-3).7



Table 2-4. Performance of broiler chicks to 21 days of age
fed various levels of supplemental boron in a practical corn-
soybean meal diet (Experiment 2)

Boron Body weight Feed Feed Mortality
sup. Males Females Average intake conversion
(ppm) (g) (g) (g) (g) (g/g*) (%)


0 637 ab 565 ab 601 ab 805 ab 1.34 4.2
60 671 a 587 a 629 a 827 a 1.31 2.1
120 600 bc 553 ab 577 b 752 bc 1.31 2.1
180 605 bc 553 ab 579 b 775 b 1.34 2.1
240 599 bc 536 bc 568 bc 753 bc 1.33 0
300 568 c 511 c 540 c 718 c 1.33 0

Pooled
SEM 13.6 12.6 10.7 16.7 .015 3.96


Grams of feed intake per grams of average body weight.

ab Values within columns followed by different letters are
significantly different (P<.05).





Boron supplementation was increased in Experiment 2

because a) the maximum mentioned index and the best feed


7 Since feed consumption values became constant once the
experiment finished any particular nutrient or any percent
of the diet could have been used as a measurement of this
relationship between consumption and mineral deposition in
the bone.








20

conversion were obtained for the birds fed the highest boron

addition in Experiment 1 and b) growth-depressing levels of

boron were not reached in Experiment 1.

The boron content of the basal diet used in Experiment 2

was 15.6 ppm boron (by analysis).

Body weight was depressed when the diets were

supplemented with more than 120, but especially over 240 ppm

boron. This tendency was slightly more marked in the case of

the average, or male, compared with the female chicks (Table

2-4). Average feed intake for the different treatments

followed the same trend as that found for body weight and

therefore no statistical differences were found for feed

conversion.

The total calcium consumption for chicks in Experiment 2

was as follows: 7.04, 7.24, 6.58, 6.78, 6.59, and 6.29 g for

treatments in increasing order of boron addition. Analysis of

the bone samples taken in Experiment 2 indicate that birds fed

diets supplemented with 300 ppm boron had the highest percent

tibia ash and the highest grams of tibia ash per calculated

grams of calcium consumption (Table 2-5).

Hunt and Nielsen (1982) and Elliot and Edwards (1990)

found beneficial effects of adding 3 ppm boron to purified

diets. However, Elliot and Edwards (1989) found that

supplementations of 20, 40, or 80 ppm boron to a practical

diet had no significant effect on any variable studied.

Perhaps the boron content of this practical diet was enough to








21

Table 2-5. Measurements of the fat-free left tibiae of broiler
chicks 21 days of age fed various levels of supplemental boron
in a practical corn-soybean meal diet (Experiment 2)

Sup. Breaking Weight Ash Ash Index
boron load
(ppm) (Kg) (g) (%) (g) (g/g*)


0 10.5 1.73 46.0 b .796 .113 b
60 10.9 1.71 46.5 b .795 .110 b
120 9.9 1.73 46.7 b .809 .123 ab
180 10.9 1.76 47.3 ab .838 .124 ab
240 9.8 1.72 47.2 ab .813 .123 ab
300 9.9 1.71 48.3 a .828 .132 a

Pooled
SEM .86 .074 .62 .0406 .0060


Grams of tibia ash per calculated total grams of
calcium consumption.

ab Values within columns followed by different letters are
significantly different (P<.05).



meet the boron requirement of the chicks.

It is apparent that the minimum requirement of boron for

best feed conversion was higher than the minimum requirement

of boron for maximum body weight. Maximum body weight for the

male chicks was achieved in Experiment 1 by supplementing the

basal diet containing 9.4 ppm boron with 5 or more ppm boron.

The content of boron of the basal diet in Experiment 2 (15.6

ppm) was probably more than that required for maximum body

weight. However, in both experiments the best feed conversions

(although not significant in Experiment 2) were achieved when

boron was supplemented at 120 ppm.







22

Antibiotics have been shown to decrease intestinal tract

weight in the chick (Pepper et al., 1953; Henry et al., 1986,

1987). This thinning of the intestine was attributed to a

prevention of the thickening in response to possible toxins

produced by intestinal microflora found in the digestive tract

when antibiotics are not fed. Henry et al. (1986) also found

that when 1,000 ppm manganese was fed the ratio of intestinal

weight to body weight decreased 5% compared to the control

group but this difference was not statistically significant.

Since previous research in this area was not conducted with

boron, its possible thinning effect was investigated in

Experiment 2. However, feeding 60 ppm boron did not diminish

significantly the small intestine weight to body weight ratio

(Table 2-6).

Muscle and liver samples contained 25.71 and 27.02% dry

matter, respectively. These mean dry matter values were used

to express the content of boron in either fresh or dry basis.

Regression analysis indicated that the correlation between

boron supplementation and tissue contents of boron was high

(Table 2-7). Chicks fed diets with boron supplementation

significantly increased their boron concentration in both

breast muscle and liver. Liver and muscle contained similar

amounts of boron in the control birds. However, muscle tissue

accumulated boron at a higher rate (slope of the regression

line) than liver when dietary boron was increased (Table 2-7).










Table 2-6. Body weight, small intestine weight, and small
intestine to body weight ratio in broiler chicks 22 days of
age fed various levels of supplemental boron in a practical
corn-soybean meal diet (Experiment 2).

Sup. Body Small Small intestine to
boron weight intestine weight body weight ratio
(ppm) (g) (g) (g/100g)


Males

0 694 24.3 3.5
60 732 25.6 3.5

Pooled SEM 52.8 3.18 .37


Females

0 647 23.9 3.7
60 631 22.6 3.6

Pooled SEM 33.3 3.91 .36


ab Values within columns followed by different letters are
significantly different (P<.05).










Table 2-7. Boron concentration in breast muscle pectoraliss
major) and in liver of broiler chicks 21 days of age fed
various levels of supplemental boron in a practical corn-
soybean meal diet (Experiment 2).

Sup. Breast muscle Liver
boron Fresh basis Dry basis Fresh basis Dry basis
(ppm) (ppm) (ppm) (ppm) (ppm)


0 .6 d 2.5 d 1.2 d 4.4 d
60 4.4 c 17.2 c 4.9 c 18.2 c
120 6.4 c 25.0 c 6.1 c 22.6 c
180 10.4 b 40.3 b 10.4 b 38.4 b
240 11.3 b 44.0 b 12.1 b 44.7 b
300 17.2 a 67.2 a 15.7 a 58.2 a

Pooled SEM 1.22 4.75 .59 2.19

Rearesion analysis Breast muscle Liver

Intercept Fresh .5796 1.2920
Intercept Dry 2.2543 4.7815
P intercepts < 0 .4544 .0027

Slope Fresh .0531 A .0475 B
Slope Dry .2064 A .1758 B
P slopes < 0 .0001 .0001

R-squared .8883 .9618


ab Values within columns followed by different letters are
significantly different (P<.05).

AB Values within rows followed by different letters are
significantly different (P<.05).














CHAPTER 3
EFFECTS OF FEEDING THREE DIFFERENT DIETARY
BORON SOURCES ON BROILERS


Introduction


Experiments involving the comparison of two different

sources of boron used as litter insecticide treatments for

breeder flocks were reported by Lee (1989) and Lee and Emmel

(1990). The aforementioned authors applied a constant amount

of boron to the litter as either tetraborate1 or octoborate2

(1,607 or 908 g/m2/week, respectively). These were the

vendor's recommended dosages, but the products were

distributed on top of the litter instead of being mixed with

it, which according to the author resulted in rapid

consumption of the products by the birds. Lee and Emmel (1990)

stated that boron in the octoborate form is more soluble than

in the tetraborate form which was supported by analysis of

tissues from birds consuming those compounds.

No other experiment comparing additions of different

sources of boron to poultry diets was found in the literature.

The objective of the present experiment was to study the


1 Na2B407.10H20, or disodium tetraborate decahydrate, or
borax.

2 Na2B80O3.4H20, or disodium octaborate tetrahydrate.







26

effects of the addition of low levels of boron from three

different dietary sources to practical corn-soybean meal diets

for broiler chicks.


Materials and Methods


Four hundred and twenty Cobb x Cobb broiler chicks were

assigned to seven treatments consisting of dietary additions

of 0 ppm boron (control), 30 or 60 ppm boron as boric acid3

(H3BO3), 30 or 60 ppm boron as boron trioxide3 (B203), or 30 or

60 ppm boron as borax3 (Na2B40.10H20).

Birds were feather-sexed at one day of age, weighed in

groups of three birds per sex, and placed for 21 days in

Petersime battery brooders4 with raised wire floors. Ten

replicates per treatment were used and six birds, three male

and three female chicks, were assigned at random to each pen.

The ambient temperature was provided and thermostatically

controlled by a central heating system and wall fans. This

temperature was set at 320C the first day of the experiment

and diminished 10C every third day. Feed and tap water were

offered ad libitum and lighting was continuous. The corn-

soybean meal basal diet used in this experiment (Table 3-1)

was formulated to meet or exceed the requirements of growing

chicks (National Research Council, 1984).




3 Reagent grade, Fisher Scientific, Fair Lawn, NJ.

4 Petersime Incubator Co., Gettysburg, OH.








27

Table 3-1. Composition of the basal diet used in the
experiment.



Ground yellow corn 55.83
Dehulled soybean meal (48.5% C.P.) 37.29
Corn oil 2.50
Dicalcium phosphate (22.0% Ca, 18.5% P) 1.72
Ground limestone 1.01
Microingredients* .50
Iodized salt .40
DL-Methionine (98%) .25
Variables" .50

SSupplied per kilogram of diet: 6,600 IU vitamin A, 2,200 IU
vitamin D3, 2.2 mg menadione dimethylpyrimidinol bisulfite,
4.4 mg riboflavin, 13.2 mg pantothenic acid, 39.6 mg niacin,
499 mg choline chloride, .022 mg vitamin B12, 125 mg
ethoxyquin, 60 mg manganese, 50 mg iron, 6 mg copper, .198 mg
cobalt, 1.1 mg iodine, and 35 mg zinc.

SContained variable amounts of washed builders' sand, boric
acid, boric anhydride, and borax, according to the different
treatments.



A sample of the basal diet used in this experiment was

microwave-digested and analyzed by emission spectroscopy for

boron content as described in Chapter 2.

At 21 days of age pen feed consumption was determined and

all birds were individually weighed. Then one male was

randomly chosen and sacrificed from each replicate. The left

leg was removed and frozen in a plastic bag for subsequent

analysis. At a later date, the legs were thawed, boiled for

five minutes, and the tibiae were excised and defleshed. The

bones were air dried at room temperature for 48 hours in an

air-conditioned room, the fat content was removed using

petroleum ether as a solvent, and then they were ashed







28

according to the procedure outlined by the Association of

Official Agricultural Chemist (1965).

Data were subjected to analysis of variance using the

General Linear Models Procedure and significant differences

were determined using Duncan's multiple range test (SAS,

1985).


Results and discussion


The basal diet used in this experiment was analyzed to

contain 18.3 ppm boron. The concentration of boron in the

municipal waters of Florida was analyzed by Carriker et al.

(1976) and found to be always less than .1 ppm.

No significant interaction between the levels and the

sources of boron was found for any variable studied in this

experiment. Although male and average body weight and feed

intake were generally higher for the different levels and

sources of boron (except for boric acid) as compared with the

control, these differences were not statistically significant

(Table 3-2).

Mortality was not significantly different among the

various treatments (Table 3-3).

Birds fed diets with the addition of borax had

significantly lower grams of ash in the tibia as compared to

the control birds (Table 3-3). However, the randomization of

the chosen birds for bone analysis was probably not complete

since the average body weight of the birds fed borax was








29

Table 3-2. Performance of broiler chicks to 21 days of age
fed three levels and three sources of supplemental boron in
a practical corn-soybean meal diet.

Boron Body weight Feed Feed
addition Males Females Average intake conversion
(g) (g) (g) (g) (g/g*)


DIm

Control 737 659 698 966 1.38
30 751 654 703 970 1.38
60 752 670 711 981 1.38

Source

Control 737 659 698 966 1.38
B acid 743 653 698 959 1.37
B trioxide 762 666 714 992 1.39
Borax 749 670 710 979 1.38


Pooled SEM 13.7 8.5 8.8 14.2 .011


Grams of feed intake per grams of average body weight.

a Significantly different from the control in the same
column (P<.05).



higher but their tibia weight was lower (P=.054) than the

control birds. Therefore, due to these questionable results it

is recommended that leg samples be analyzed by selecting those

birds whose body weight is closest to the mean of the pen

rather than selecting them at random.

In conclusion, various boron levels supplied by different

dietary sources resulted in average body weights numerically

equal to or greater than the control group but this difference

was not statistically significant.










Table 3-3. Measurements of the fat-free left tibiae and
cumulative mortality of broiler chicks 21 days of age fed
three levels and three sources of supplemental boron in a
practical corn-soybean meal diet.

Boron Tibia Cumulative
addition Weight Ash Ash mortality
(g) (%) (g) (%)


ppm

Control 2.62 39.2 1.03 1.7
30 2.61 38.7 1.01 5.0
60 2.47 39.4 .97 3.3

Source

Control 2.62 39.2 1.03 1.7
B acid 2.70 39.9 1.08 6.7
B trioxide 2.57 38.6 .99 5.0
Borax 2.33 38.7 .89 a 1.7


Pooled SEM .106 1.75 .048 2.63


a Significantly different from the control in the same
column (P<.05).














CHAPTER 4
THE INTERACTION OF BORON WITH CALCIUM, PHOSPHORUS,
AND VITAMIN D3 IN BROILERS


Introduction


Hunt and Nielsen (1982) supplemented a purified diet

containing only .28 ppm boron with 3 ppm boron and either

adequate or deficient amounts of Vit. D3. The aforementioned

authors found an interrelationship between boron and Vit. D3.

Boron supplementation improved chick body weight at 32 days of

age by 11% when the Vit. D3 content of the diet was adequate

(2500 IU/Kg) and by 38% when the Vit. D3 was deficient (125

IU/Kg). Elliot and Edwards (1990) used a factorial design

involving the addition of calcium, Vit. D3, and boron to

purified diets for broilers. These authors found that the

addition of 3 ppm boron tended to increase bone ash (P = .06),

and that there was a significant interaction between boron and

Vit. D3 on weight gain.

Calcium and phosphorus metabolism could be affected

indirectly through the above interrelationship between boron

and Vit. D3 or through the steroid hormone levels. In

postmenopausal women, Nielsen et al. (1987) found that boron

supplementation elevated the serum concentrations of estradiol

and testosterone. These steroid hormones are so important for







32

maintaining bone and calcium status that estrogen replacement

therapy is currently the only proven treatment for

osteoporosis (Nielsen and Hunt, 1987). Nielsen et al. (1987)

also reported that women receiving the boron treatment lost

one-third less magnesium and 40% less calcium through urinary

excretion and retained an average of 52 mg more calcium per

day.

In sheep, boron supplementation of 75 or 200 mg/day to a

daily consumption of 30 mg boron increased calcium

digestibility and calcium retention at each level of boron

addition (Brown et al., 1988).

There is also the possibility of a direct influence of

boron on mineral metabolism. Boron and phosphorus are of

similar atomic size1 and they may compete for the same

cellular site as first proposed by Pfeiffer et al. (1945). In

a field study with heifers, Green and Weeth (1977) found that

urinary excretion of phosphate was decreased and plasma

phosphate was increased by adding 150 and 300 ppm boron to the

water.


Materials and Methods


Four hundred and thirty-two Cobb x Cobb broiler chicks

were assigned to eight treatments consisting of diets with





1 The radii in Angstrom units are .9 and 1.1 for boron and
phosphorus atoms, respectively (Nebergall et al., 1972).








33

different levels of calcium and phosphorus, as well as

different supplementation levels of boron and Vit. D3.

Birds were feather-sexed at one day of age, weighed in

groups of three birds per sex, and housed for 21 days in

Petersime battery brooders2 with raised wire floors. Nine

replicates per treatment were used and six birds, three male

and three female chicks, were assigned at random to each pen.

The ambient temperature was provided and thermostatically

controlled by a central heating system and wall fans. This

temperature was set at 32C the first day of the experiment

and diminished 10C every third day. Feed and tap water were

offered ad libitum and lighting was continuous.

The corn-soybean meal basal diet used in this experiment

is presented in Table 4-1. The nutrient contents of the

different dietary treatments were calculated from the

ingredient composition of the feedstuffs as reported by the

National Research Council (1984). Diets 1, 2, 3, and 4 were

not supplemented with boron while diets 5, 6, 7, and 8 were

supplemented with 60 ppm boron as boron trioxide3 (B203).

Diets 1, 2, 3, 5, 6, and 7 were supplemented with 2,200 IU

Vit. D3/Kg while diets 4 and 8 were supplemented with only 100

IU Vit. D3/Kg. Diets 1, 4, 5, and 8 were formulated to contain

.9% calcium and .45% non-phytate phosphorus. Diets 3 and 7

were formulated to contain 1.2% calcium and .60% non-phytate


2 Petersime Incubator Co., Gettysburg, OH.

3 Reagent grade. Fisher Scientific, Fair Lawn, NJ.







34

phosphorus while diets 2 and 6 were formulated to contain

only .60% calcium and .30% non-phytate phosphorus.



Table 4-1. Composition of the basal diet used in the
experiment.



Ground yellow corn 52.33
Dehulled soybean meal (48.5% C.P.) 37.79
Corn oil 4.00
Microingredients* .50
Iodized salt .40
DL-Methionine (98%) .25
Variables** 4.73


Supplied per kilogram of diet: 6,600 IU vitamin A, 2.2 mg
menadione dimethylpyrimidinol bisulfite, 4.4 mg riboflavin,
13.2 mg pantothenic acid, 39.6 mg niacin, 499 mg choline
chloride, .022 mg vitamin B12, 125 mg ethoxyquin, 60 mg
manganese, 50 mg iron, 6 mg copper, .198 mg cobalt, 1.1 mg
iodine, and 35 mg zinc.

Contained variable amounts of washed builders' sand,
dicalcium phosphate (22.0% calcium, 18.5% phosphorus), ground
limestone, boric acid, and Vit. D3, according to the different
treatments.



A sample of the basal diet used in this experiment was

microwave-digested, and analyzed for boron by emission

spectroscopy as described in Chapter 2.

At 21 days of age pen feed consumption was determined and

all birds were individually weighed. Then one male from each

replicate whose body weight was the closest to the mean of the

pen was chosen and killed by cervical dislocation. The right

leg was removed and defleshed, and an identification ring was

attached to it. The legs were randomized and a cut of the








35

proximal tibial epiphysis was made at approximately 450 from

the longitudinal axis. The bones were then scored according to

the degree of severity of tibial dyschondroplasia4 by a team

of four persons. All values were agreed prior to the beginning

of the scoring process, being 0 for the normal case, 1 for the

mild case, 2 for the moderate case, 3 for the marked case, and

4 for the severe case. The left leg was also removed and

frozen in a plastic bag for subsequent analysis. At a later

date, the legs were thawed, boiled for five minutes, and the

tibiae were excised and defleshed. The bones were air dried at

room temperature for 48 hours in an air-conditioned room, the

fat content was removed using petroleum ether as a solvent,

and then they were ashed according to the procedure outlined

by the Association of Official Agricultural Chemists (1965).

Data were analyzed by using programs from SAS (1985).

Analysis of variance was performed using the General Linear

Models Procedure. Significant differences for the interactions

between the different factors were determined by using

orthogonal contrasts. Separation of the means was done by

using Duncan's multiple range test.










4 Cartilage abnormality first described by Leach and Nesheim
(1965), and coined by Siller (1970).










Results and discussion


The lowest male, female, and average body weights were

observed for the birds consuming diets with 100 IU/Kg of Vit.

D3 supplementation (Table 4-2). The addition of 60 ppm boron

to these diets did not improve the body weight depression

caused by the Vit. D3 deficiency.



Table 4-2. Performance of broiler chicks to 21 days of age
fed different levels of calcium (Ca) and non-phytate
phosphorus (P), and supplemented with different amounts of
boron (B) and Vit. D3 (D3) in a corn-soybean meal diet.

Treatments Body weight Feed Feed Morta-
Ca P B D3 Males Females Average intake conv. lity
% % ppm IU/Kg (g) (g) (g) (g) (g/g*) (%)


.9 .45 0 2,200 746 a 660 a 703 a 939 a 1.34 5.5
.6 .30 0 2,200 701 ab 646 a 673 abc 908 ab 1.35 0
1.2 .60 0 2,200 740 a 656 a 698 ab 926 a 1.33 0
.9 .45 0 100 605 c 590 b 597 d 806 c 1.35 0
.9 .45 60 2,200 702 ab 647 a 674 abc 898 ab 1.33 1.9
.6 .30 60 2,200 672 b 628 a 650 c 874 b 1.34 1.9
1.2 .60 60 2,200 702 ab 633 a 668 bc 901 ab 1.35 0
.9 .45 60 100 604 c 541 c 572 d 782 c 1.37 0

Pooled SEM 14.8 12.5 10.0 13.4 .014 2.29


Feed conversion as grams of feed intake per grams of
average body weight.

abc Values in the same column followed by different letters
are significantly different (P<.05).



When comparing these results with previous experiments on

boron supplementation the composition of the basal diets must

also be considered. In Hunt and Nielsen's experiment (1982),

the average body weight at 32 days of age for the chicks fed








37

125 IU/Kg Vit. D3 was 561 and 775 g for the 0 and 3 ppm boron

supplementation, respectively. However, in the present

experiment the chicks supplemented with 100 IU/Kg Vit. D3

weighed almost 600 g at only 21 days of age. This difference

in results was probably due to the different nutrients,

including boron, of the basal diets utilized in those

experiments. While Hunt and Nielsen's (1982) basal diet

contained only .28 ppm boron the basal diet utilized in this

experiment contained 22.3 ppm boron. Boron concentration of

the municipal waters of Florida was analized by Carriker et

al. (1976) and found to be always less than .1 ppm.

Feeding low levels of calcium and non-phytate phosphorus

also resulted in decreased male and average body weights.

Again, these body weights were not significantly affected by

the addition of boron to these diets (Table 4-2).

Feed intake changed in proportion to the changes in body

weight and therefore, there were no significant differences

among the treatment means for feed conversion (Table 4-2). The

result of previous experiments at this experiment station (see

Chapter 1) indicated that the best feed conversion values were

achieved with boron additions of about 120 ppm (or twice the

amount supplemented in this experiment).

Birds fed either low levels of calcium and non-phytate

phosphorus (.60 and .30, respectively) or low levels of Vit.

D3 supplementation (100 IU/Kg) had significantly lower percent

tibia ash than birds fed the other treatments (Table 4-3).








38

Table 4-3. Fat-free tibia weight and ash, and tibial
dyschondroplasia score of broiler chicks 21 days of age fed
different levels of calcium (Ca) and non-phytate phosphorus
(P), and supplemented with different amounts of boron (B) and
Vit. D3 (D3) in a corn-soybean meal diet.

Treatments Tibia Tibial
Ca P B D3 Weight Ash Ash dyschondroplasia
% % ppm IU/Kg (g) (%) (g) score


.9 .45 0 2,200 2.50 a 41.6 a 1.04 a .89 b
.6 .30 0 2,200 2.31 ab 35.9 b .83 cd 1.89 b
1.2 .60 0 2,200 2.31 ab 42.0 a .96 ab 1.00 b
.9 .45 0 100 2.16 b 36.9 b .80 d 3.67 a
.9 .45 60 2,200 2.19 ab 39.6 a .87 bcd 1.44 b
.6 .30 60 2,200 2.08 b 35.1 b .73 d 1.22 b
1.2 .60 60 2,200 2.32 ab 40.9 a .95 abc .89 b
.9 .45 60 100 2.11 b 35.7 b .75 d 3.56 a

Pooled SEM .100 .83 .043 .454


Degree of severity as follows: 0 for the normal case, 1
for the mild case, 2 for the moderate case, 3 for the
marked case, and 4 for the severe case.

abc Values in the same column followed by different letters
are significantly different (P<.05).



Edwards and Veltmann (1983), and Edwards (1984) conducted

several experiments (2 and 8, respectively) concerning the

effect of calcium and phosphorus on tibial dyschondroplasia

and found that at the same calcium level higher levels of

phosphorus increased the incidence of tibial dyschondroplasia

in chicks. However, in one of the experiments conducted by

these authors calcium and non-phytate phosphorus were

maintained at a ratio of 2:1 and in this case the incidence of

tibial dyschondroplasia did not increase. These results are in

agreement with the results of the present experiment in which








39

the incidence of tibial dyschondroplasia was not affected by

the levels of calcium and non-pytate phosphorus which were

maintained at a 2:1 ratio (Table 4-3). Therefore, these

results support the hypothesis that tibial dyschondroplasia

depends on the cation-anion balance of the diet as stated by

Leach and Nesheim (1972), by Mongin and Sauveur (1977), by

Nelson et al. (1981), and by Halley et al. (1987).

Tibial dyschondroplasia score was found to change greatly

with the level of Vit. D3 in the diet. Average tibial

dischondroplasia scores for the low (100 IU/Kg) Vit. D3-fed

chicks were equivalent to a degree between marked and severe.

These scores were significantly higher than those of the birds

fed high levels of Vit. D3 (2,200 IU/Kg) which average tibial

dyschondroplasia score did not even reach a mild case (Table

4-3).

When the level of Vit. D3 in the diet was adequate the

levels of calcium and phosphorus at which minimization of

tibial dyschondroplasia scored were observed tended to depend

on the level of boron supplemented. The interaction between

boron and calcium and phosphorus levels in adequate Vit. D3

diets was almost significant (P=.056).

The addition of 60 ppm boron did not influence bone ash

(Table 4-3). This agrees with previous research conducted at

this experiment station with practical diets in which boron

increased percent tibia ash only when supplemented at a level

of 300 ppm.








40

The values obtained for tibia weight are consistent with

the mean body weight of the birds in the different dietary

treatments.














CHAPTER 5
EFFECTS OF SALT (NACL) WITHDRAWAL AND DIETARY BORON
SUPPLEMENTATION ON THE PERFORMANCE AND BONE
DEVELOPMENT OF CHICKS



Introduction


A considerable number of experiments have been conducted

involving different dietary levels of sodium and chloride in

chicks (Nott and Combs, 1969; Dewar and Whitehead, 1973;

Walicka et al., 1979; Egwuatu et al., 1983; Damron and

Johnson, 1985; Proudfoot et al., 1985; Damron et al., 1986;

Pimentel and Cook, 1987) However, no experiment was found in

the literature in which salt (NaCl) was withdrawn and later

refed to the same birds.

In studies with poultry, boron has been found to interact

with Vit. D3 (Hunt and Nielsen, 1982; Elliot and Edwards,

1990), with riboflavin (Roe et al., 1972), with magnesium and

molybdenum (Hunt and Nielsen, 1986), and with iodophor

products (Lee and Emmel, 1990). In studies with other animals

boron has also been found to interact with phosphorus (Green

and Weeth, 1977), calcium (Brown et al., 1988), magnesium and

aluminum (Nielsen, 1986a).








42

The objective of this experiment was to study the effects

of salt withdrawal and subsequent refeeding in diets with or

without boron supplementation.


Materials and Methods


Cobb x Cobb birds were feather-sexed at one day of age

and one hundred and forty-four males were weighed in groups of

six and placed at random for 21 days in each of the 24 pens of

a Petersime battery.

The four treatments utilized in this experiment consisted

of feeding a corn-soybean meal basal diet (Table 5-1) with or

without salt supplementation (0 or .40%) during the first

seven days of age combined with the addition of either 0 or 20

ppm boron as boric acid. Each experimental diet was assigned

to six pens of birds. After the first week of the experiment

all birds received the same level of salt supplementation

(.40%). The basal diet was formulated to meet or exceed the

requirements of growing chicks (National Research Council,

1984).

A sample of the basal diet used in this experiment was

microwave-digested and analyzed for boron by emission

spectroscopy as described in Chapter 2.

The ambient temperature was provided and thermostatically

controlled by a central heating system and wall fans. This

temperature was set at 320C the first day of the experiment


1 Petersime Incubator Co., Gettysburg, OH.








43

Table 5-1. Composition of the basal diet used in the
experiment.
%

Ground yellow corn 55.83
Dehulled soybean meal (48.5% C.P.) 37.29
Corn oil 2.50
Dicalcium phosphate (22.0% Ca, 18.5% P) 1.72
Ground limestone 1.01
Microingredients* .50
DL-Methionine (98%) .25
Variables** .90


Supplied per kilogram of diet: 6,600 IU vitamin A, 2,200 IU
vitamin D3, 2.2 mg menadione dimethylpyrimidinol bisulfite,
4.4 mg riboflavin, 13.2 mg pantothenic acid, 39.6 mg niacin,
499 mg choline chloride, .022 mg vitamin B12, 125 mg
ethoxyquin, 60 mg manganese, 50 mg iron, 6 mg copper, .198 mg
cobalt, 1.1 mg iodine, and 35 mg zinc.
** Contained variable amounts of washed builders' sand, iodized
salt, and boric acid, according to the different treatments.



and diminished 10C every third day. Feed and deionized water

were offered ad libitum and lighting was continuous.

At 7, 14, and 21 days of age pen feed consumption was

determined and all birds were individually weighed. Then, one

male whose body weight was the closest to the mean of the pen

was chosen from each replicate and killed by cervical

dislocation. The right leg was removed, defleshed, and an

identification ring was attached to it. The legs were

randomized and a cut of the proximal tibial ephiphysis was

made at approximately 450 from the longitudinal axis. The

bones were then scored according to the degree of severity of








44

tibial dyschondroplasia2 by a team of four persons. All values

were agreed upon prior to the beginning of the scoring

process, with 0 representing the normal case, 1 the mild case,

2 the moderate case, 3 the marked case, and 4 the severe case.

The left leg was removed and frozen in a plastic bag for

subsequent analysis. At a later date, the legs were thawed,

boiled for five minutes, and the tibiae were excised and

defleshed. The bones were air dried at room temperature for 48

hours in an air-conditioned room, the fat content was removed

using petroleum ether as a solvent, and then they were ashed

according to the procedure outlined by the Association of

Official Agricultural Chemists (1965).

Data were subjected to analysis of variance using the

General Linear Models Procedure and significant differences

were determined by Duncan's multiple range test (SAS, 1985).


Results and discussion


The basal diet utilized in this experiment contained 21.9

ppm boron.

Birds fed the diets with no salt supplementation for the

first week of age had lower weekly body weight gain, lower

body weight, and lower feed consumption at 7, 14, and 21 days

of age compared to birds fed .40% salt (Table 5-2).




2 Cartilage abnormality first described by Leach and Nesheim
(1965), and coined by Siller (1970).










Table 5-2. Performance of male broiler chicks to 7, 14, and
21 days of age fed a corn-soybean meal diet with (+) or
without (-) .40% salt supplementation for the first seven days
of age combined with the addition of 0 or 20 ppm boron as
boric acid.

Treatments Weekly Body Feed Feed
Salt Boron BW gain Weight intake conversion
Wk 1 ppm (g) (g) (g) (g/g*)


Seven davs of ace


91 a
42 b
94 a
42 b


Pooled SEM


2.5


138 a
89 b
141 a
89 b

2.5


138 a
99 b
143 a
98 b

2.5


1.00 b
1.12 a
1.02 b
1.10 a

.013


Fourteen days of age


232 a
153 b
230 a
148 b


370 a
242 b
371 a
237 b


451 a
322 b
457 a
314 b


1.22 b
1.34 a
1.23 b
1.33 a


Pooled SEM


8.2


10.1


9.8


.017


Twenty-one days of aae


Pooled SEM


341 a
291 b
335 a
272 b

8.7


710 a
533 b
706 a
509 b

16.7


983 a
737 b
987 a
707 b

24.3


1.38
1.38
1.40
1.43

.017


Grams of feed intake per grams of average body weight.

abc For the same age, values in the same column followed by
different letters are significantly different (P<.05).








46

Body weight depression in chicks fed no supplemental salt

was in agreement with previous studies (Nott and Combs, 1969;

Dewar and Whitehead, 1973; Egwuatu et al., 1983; Damron and

Johnson, 1985; Proudfoot et al., 1985; Damron et al., 1986;

Pimentel and Cook, 1987). Lower feed intake in birds subjected

to the salt-withdrawal treatment also agreed with prior

studies (Walika et al. ,1979; Damron and Johnson, 1985; Damron

et al., 1986; Pimentel and Cook, 1987).

During the salt withdrawal period (first week) the chicks

fed no supplemental salt had less than half the weekly body

weight gain of the other chicks. However, after the adequate

salt diet was refed the weight gain of the group previously

fed no salt was 65% for the second week, and 83% for the third

week, of that of the other birds.

Feed conversion at 7 and 14 days of age was significantly

poorer for the group fed no salt in comparison with the

others. Such results are in agreement with other studies (Nott

and Combs, 1969; Dewar and Whitehead, 1973; Egwuatu et al.,

1983; Pimentel and Cook, 1987). However, at 21 days there were

no significant differences among the treatments for feed

conversion.

Supplementation of either the adequate salt or the

unsupplemented salt diets with 20 ppm boron did not have any

impact on body weight, feed intake, or feed conversion (Table

5-2).







47

Effects of the treatments on tibia weight, tibia ash, and

grams of ash in the tibia were already evident at seven days

of age (Table 5-3). However, tibial dyschondroplasia scores

were not affected until the third week of age. At seven days

of age percent tibia ash tended to be lower for the salt

withdrawal treatment. This is in agreement with Egwuatu et al.

(1983).

At three weeks of age chicks in the salt withdrawal

treatment with 20 ppm boron supplementation had lower tibia

weight and lower percent tibia ash compared to the other

treatments. The combination of these two effects resulted in

a 45% lower value for grams tibia ash than that of the control

birds (.53 vs .94 g). This ash deposition in the tibia was 30%

lower even when adjusted for body weight. Unexpectedly, boron

was found to be detrimental when supplemented in small amounts

(20 ppm) to salt-deficient diets. Such results seem to

indicate that the salt level needs to be considered when boron

is supplemented.

On the other hand, addition of boron to the salt

withdrawal treatment reduced the incidence of tibial

dyschondroplasia at three weeks of age (Table 5-3). However,

this lower score could be related to the lower tibia weight of

those birds since tibial dyschondroplasia severity was

dependent on the age of the birds (Table 5-3).










Table 5-3. Fat-free tibia weight and ash, and tibial
dyschondroplasia score of broiler chicks at 7, 14, and 21 days
of age fed a corn-soybean meal diet with (+) or without (-)
.40% salt supplementation for the first seven days of age
combined with the addition of 0 or 20 ppm boron as boric acid.

Treatments Tibia Tibial
Salt Boron Weight Ash Ash dyschondroplasia
Wk 1 ppm (g) (%) (g) score


Seven days of age


Pooled SEM


.37 a
.25 b
.34 a
.23 b

.013


34.3 a
33.1 ab
34.9 a
31.3 b

.88


.13
.08
.12
.07


.005


Fourteen days of ace


1.21 a
.75 b
1.33 a
.79 b


Pooled SEM


.054


34.3
31.3
32.0
30.3


1.34


.41
.23
.43
.24


.17
.33
.17
.50


.021


.184


Twenty-one days of age


Pooled SEM


2.50 a
1.94 bc
2.28 ab
1.60 c

.118


37.3 a
37.1 a
36.5 a
32.7 b

1.03


.94 a
.72 b
.83 ab
.53 c

.053


.67 ab
1.00 a
.33 ab
0 b

.255


Grams of feed intake per grams of average body weight.

abc For the same age, values in the same column followed by
different letters are significantly different (P<.05).














CHAPTER 6
DIETARY BORON AND RIBOFLAVIN SUPPLEMENTATION
FOR BROILERS FED TO 49 DAYS OF AGE


Introduction


In studies with poultry boron has been found to interact

with Vit. D3 (Hunt and Nielsen, 1982; Elliot and Edwards,

1990), with magnesium and molybdenum (Hunt and Nielsen, 1986),

and with iodophor products (Lee and Emmel, 1990). In studies

with other animals boron has also been found to interact with

phosphorus (Green and Weeth, 1977), calcium (Brown et al.,

1988), magnesium and aluminum (Nielsen, 1986a).

Frost (1942) showed that stable aqueous solutions of at

least 25 times the natural solubility of riboflavin could be

prepared in the lab by addition of borates. This led to the

conclusion of the existence of water-soluble riboflavin-boron

complexes. Wadke and Guttman (1964) also reported riboflavin-

borate complexes formed by the combination of boric acid with

the side-chain of riboflavin.

By studying the urinary excretion of radioactively marked

riboflavin, Roe et al. (1972) demonstrated in rats and guinea

pigs that riboflavin depletion can be induced by borate. These

authors proposed that the mode of action of borates on

riboflavin excretion via the kidney was by detaching this







50

vitamin from binding sites on serum proteins, through

formation of flavin-borate complexes. This situation is

analogous to the avian recessive disorder of renal

riboflavinuria in which massive urinary loss of the vitamin

occurs due to deficiency of the normal flavin-binding protein

in the serum (Winter et al., 1967).

Riboflavin deficiency signs in dead embryos (Lee, 1989)

and increased weight of the thyroid gland (Lee and Emmel,

1990) were found after application of borate insecticides to

the litter of their parent flock. This research seems to

confirm that boron toxicity causes riboflavin depletion.

Landauer (1952) found that the injection of boric acid in

the yolk of developing embryos led to various malformations.

Riboflavin, dissolved in boric acid, greatly reduced the

teratogenic properties of boric acid. The livers of boric

acid-treated and morphologically abnormal embryos were

deficient in riboflavin. After these findings the author

assumed that the morphogenetic effects of boric acid were

mediated via complexation of riboflavin-containing enzymes.

However, Landauer (1953) found that other polyhydroxy

compounds besides riboflavin (D-ribose, pyridoxine

hydrochloride, D-sorbitol hydrate) also completed with boric

acid and reduced its teratogenic qualities. Therefore, the

author concluded that boric acid interferes with normal

development by complex formation in ovo with polyhydroxy








51

compounds, thereby producing signs resembling riboflavin

deficiency.

The objectives of this research were to determine if the

addition of different amounts of boron to practical corn-

soybean meal diets for poultry would result in toxicity

as well as to determine whether or not additional riboflavin

would counteract the possible toxic effects.


Materials and Methods


Six hundred and seventy-two Ross x Ross broiler chicks

were feather-sexed at one day of age and seven males and seven

females were assigned at random to each of 48 floor pens. The

birds were housed on litter (pine shavings) in 56.4-m2 pens to

49 days of age.

The dietary treatments consisted of feeding practical

corn-soybean meal basal diets (Table 6-1) supplemented with a

combination of two levels of riboflavin' (4.4 or 17.6 ppm) and

four levels of boron (0, 20, 80, or 320 ppm) as boric acid2.

The basal diets were formulated to meet or exceed the

requirements of growing chicks (National Research Council,

1984). The starter basal diet was fed until 21 days of age

while the finisher basal diet was fed from 22 to 49 days of

age.


Reagent grade, 96% purity, Roche Chemical Division,
Hoffmann-LaRoche, Inc., Nutley, NJ.

2 Reagent grade, 17.5% boron, Fisher Scientific, Fair Lawn,
NJ.










Table 6-1. Composition of the starter (0-3 wk) and
(4-7 wk) basal diets used in the experiment.


Ground yellow corn
Dehulled soybean meal (48.5% C.P.)
Corn oil
Dicalcium phosphate (22.0% Ca, 18.5% P)
Ground limestone
Microingredients*
Iodized salt
DL-Methionine (98%)
Coban-45
Variables*


Starter


55.73
37.29
2.50
1.72
1.01
.50
.40
.25
.10
.50


52

finisher


Finisher
(%)

62.65
29.61
3.63
1.84
.97
.50
.40
.30
.10
.50


Supplied per kilogram of diet: 6,600 IU vitamin A, 2,200 IU
vitamin D3, 2.2 mg menadione dimethylpyrimidinol bisulfite,
13.2 mg pantothenic acid, 39.6 mg niacin, 499 mg choline
chloride, .022 mg vitamin B12, 125 mg ethoxyquin, 60 mg
manganese, 50 mg iron, 6 mg copper, .198 mg cobalt, 1.1 mg
iodine, and 35 mg zinc.

SContained variable amounts of washed builders' sand,
riboflavin, and boric acid according to the different
treatments.



A sample of the basal diet used in this experiment was

microwave-digested (Schelkop, 1988) and analyzed for boron

content using an ICP instrument as described in Chapter 2.

The heating source was a single infrared bulb (250 Watt)

for each pen which was thermostatically controlled to provide

a minimum ambient temperature of 300C the first week and was

diminished 20C weekly. Feed and tap water were offered ad

libitum and lighting was continuous.

At 21 and 49 days of age pen feed consumption was

determined and all birds were individually weighed. At 49

days one male whose body weight was the closest to the mean of








53

the pen was chosen and killed by cervical dislocation from

each replicate. The left leg was removed and frozen in a

plastic bag for subsequent analysis. At a later date, the legs

were thawed, boiled for five minutes, and the tibiae were

excised and defleshed. The bones were air dried at room

temperature for 48 hours in an air-conditioned room, the fat

content was removed using petroleum ether as a solvent, and

then they were ashed according to the procedure outlined by

the Association of Official Agricultural Chemists (1965).

Based on U.S. average prices from 1984 to 1989 (Table 6-

2) a price-sensitivity economic analysis was made for each of

the 48 pens of the experiment in three different profit

scenarios. The worst profit scenario was obtained by using the

highest feed costs and the lowest broiler prices. Mode costs

and prices were used to calculate the average price scenario.

The best price scenario was derived from the use of the lowest

costs and the highest prices. In each of these three price

scenarios the profits were calculated by two different

methods. In the first method the total amount of starter and

grower feed consumed in each pen was used to calculate the

profits. This is the method used in commercial situations. In

the second method the feed consumed by the birds that died

during the experiment was not considered as a cost. This

method was designed to avoid the influence of mortality on the

profits.








54
Table 6-2. Costs and prices used for the price-sensitivity
analysis of broiler chicks grown to 49 days of age and fed a
practical corn-soybean meal diet supplemented with different
amounts of riboflavin and boron.

Item paid by (costs) Level
or received by Lowest Mode Highest
(price) farmers ----- cents per kilogram -----



Cost of starter feed 21.2 24.0 26.8
Cost of grower feed 20.5 23.5 26.0
Price of broilers 54.0 71.0 86.1

Source: Weimar and Cromer (1987), and USDA (1989).



The amount of starter and grower feed consumed by each

pen was multiplied by their respective prices to obtain the

cost of feeding. The total catch weight of each pen was

multiplied by the price of broilers received by farmers to

calculate the pen income. On the basis that variable costs

rather than fixed costs influence economic decisions (Blair

and Kenny, 1987) the costs other than feeding were arbitrarily

held at 40.4 cents per chick housed (about 40% of total

costs). Total costs were calculated as feed costs plus other

costs. The profits were calculated as total income minus total

costs.

Data were subjected to analysis of variance and

significant differences were determined by Duncan's multiple

range test (SAS, 1985).










Results and discussion


The basal diet utilized in this experiment was analyzed

to contain 22.3 ppm boron. Carriker et al. (1976) found that

the boron concentration of the municipal waters of Florida was

always less than .1 ppm.

The lowest male, female, and average body weights at 21

and 49 days of age were observed for the birds consuming diets

with 320 ppm of boron supplementation (Table 6-3).

The addition of 17.6 ppm riboflavin to diets with 320 ppm

boron supplementation did not alleviate the body weight

depression caused by the boron toxicity. This seems to

disagree with the results of the experiment of Roe et al.

(1972) who found that .8 % boric acid (1,400 ppm boron3)

severely impaired growth of White Leghorn chicks in diets

containing 7 ppm riboflavin, but when the chicks received

diets containing 14 ppm riboflavin their body weight was

significantly improved. However, these authors found that

further improvement in growth was not obtained by increasing

riboflavin levels to 28 ppm. After 21 days on the latter diet

their body weight was about half that of the control group fed

no supplemental boron. Apparently, there is a maximum level

beyond which there is no effect of riboflavin on boron

toxicity alleviation. One difference in methodology was that

in the experiment of Roe et al. (1972) the birds were kept in


3 Calculated from dosage and boron content of boric acid
(17.5% boron).



























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57

cages while in the present experiment birds were raised on the

floor and perhaps birds could obtain additional riboflavin

through litter consumption.

It was previously shown that boron forms complexes with

D-ribose, pyridoxine hydrochloride, D-sorbitol hydrate

(Landauer, 1953). It was also shown that boron inactivates

alkaline phosphatase (Zittle and Della Monica, 1950) and

xanthine oxidase (Roush and Norris, 1950). Therefore,

increasing riboflavin intake alone may not provide protection

against detrimental effects of high boron levels.

However, when 17.6 ppm riboflavin was added in

combination with 320 ppm boron, at 49 days of age feed

consumption was the lowest and feed conversion was the best of

all other treatment groups (Table 6-3). This advantage in feed

conversion diminishes if it is adjusted for differences in

body weight. From the linear trend observed from 21 to 49 days

of age it was calculated that .07 units of feed conversion

should be added to the group fed the highest levels of

riboflavin and boron if body weight is to be adjusted to 2,100

grams. After this adjustment, all groups fed supplemental

boron to 49 days of age were similarly efficient in feed

conversion but significantly better than the birds not fed

boron (data not presented).

No significant differences among the treatments were

found for tibia weight or tibia ash (Table 6-4).








58

Table 6-4. Fat-free tibia weight, and ash of broiler chicks
49 days of age fed a corn-soybean meal supplemented with
different amounts of riboflavin and boron.

Treatment Tibia
Riboflavin Boron Weight Ash Ash
ppm ppm (g) (%) (g)


4.4 0 7.76 41.3 3.20
4.4 20 7.90 41.9 3.30
4.4 80 7.58 42.5 3.22
4.4 320 7.69 41.4 3.19
17.6 0 8.07 42.5 3.43
17.6 20 8.17 41.5 3.38
17.6 80 7.79 42.2 3.29
17.6 320 7.51 42.7 3.21

Pooled SEM .417 .63 .180


abc Values in the same column with different letters are
significantly different (P<.05).



There was a significant interaction between boron and

riboflavin levels that affected profits in the worst profit

scenario. The profits increased with the boron levels at 17.6

ppm riboflavin. However, at 4.4 ppm riboflavin the profits

stayed more or less at the same level (Table 6-5).

Boron supplementation of 20 or 80 ppm resulted in higher

profits compared to 0 or 320 ppm in the average and best price

scenarios (Table 6-5, Figure 6-1, Figure 6-2). The main

effects of the two levels of riboflavin supplementation were

not significantly different at either the average or the best

price scenario (data not presented). The method of calculating

the profits (either including or excluding the feed consumed

by the birds that died) basically did not affect the results.











Table 6-5. Economic performance of broiler chicks to 49 days
of age fed a corn-soybean meal diet supplemented with
different amounts of riboflavin (Rib.) and boron.

Treatment Profit Difference from control
Rib. Boron All birds Adjusted* All birds Adjusted*
ppm ppm -------($/pen)------- --------($/pen)-------


Worst profit scenario


4.4
4.4
4.4
4.4
17.6
17.6
17.6
17.6


0
20
80
320
0
20
80
320


-5.82
-5.40
-5.72
-5.88
-6.06
-5.90
-5.25
-5.16


Pooled SEM


bdc
abc
abcd
cd
d
cd
ab
a


.181


-5.64
-5.33
-5.29
-5.54
-5.84
-5.24
-5.28
-5.03


0
.42
.10
-.06
-.24
-.08
.57
.66


0
.31
.35
.10
-.20
.40
.36
.61


.081


Average profit scenario


0
20
80
320

Pooled SEM


Best profit scenario


0
20
80
320


Pooled SEM


.38 b
1.02 ab
1.18 a
.49 b

.232


.56 b
1.35 a
1.37 a
.70 b


0
.64
.80
.11


.147


0
.79
.81
.14


6.42 b
7.38 a
7.54 a
6.22 b


.329


6.57 b
7.67 a
7.71 a
6.40 b


0
.96
1.12
-.20


.257


0
1.10
1.14
-.17


* Feed consumed by birds that died was discounted.

abc Values in the same column with different letters are
significantly different (P<.05).




















































0 20


BORON S.~ LEMENTATIr; (CFP.)


Figure
profits


6-1. Effect of boron supplementation on adjusted
from broiler production (average profit scenario).















































3 -- -- _____-.


.. 5 --EMENTATH I I .


Figure 6-2. Effect of boron supplementation on adjusted
profits from broiler production (best profit scenario).


-M7SS~


-1-














CHAPTER 7
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON LAYING HENS


Introduction


Few experiments have been conducted concerning the

effects of boron on laying hen performance. Sherwood (1959),

studied the effects of supplementing a borate-based larvicidal

drug (Polybor 3) to laying hen diets at levels of 0, 2, 3, and

6 pounds per ton, i.e. 0, 210, 315, and 629 ppm boron1,

respectively. The 629 ppm boron level resulted in complete

inhibition of viable fly larvae but egg production of layers

was markedly poorer. However, at the 315 ppm boron level about

half of the expected larvae developed while egg production was

only slightly lower than that of the control birds. Other

production variables were not reported by the author.

Lee (1989), and Lee and Emmel (1990) applied a constant

amount of boron as either tetraborate2 or octoborate3 (1,607

or 908 g/m2/week, respectively) on top of the litter of Single



1 Calculated from dosage and boron content of Polybor 3:
disodium octaborate tetraydrate (20.97%).

2 Na2B407.10H20, or disodium tetraborate decahydrate, or
borax.

3 Na2g803.4H20, or disodium octaborate tetrahydrate.








63

Comb White Leghorn hens. Subsequently, a significant reduction

in egg production, fertility, and hatchability occurred.

The objective of the present experiment was to study the

effects of supplementing practical corn-soybean meal laying

hen diets with various amounts of boron.


Materials and Methods


Two hundred and eighty 36-week old, Single Comb White

Leghorn hens (Hyline W-36) were assigned at random to four

dietary treatments for 56 days. Each treatment had seven

replicates of ten individually caged birds. The dietary

treatments consisted of supplementating a corn-soybean meal

basal diet (Table 7-1) with 0, 20, 40, and 80 ppm boron

supplied as boric acid4 (H3BO3, 17.50% boron).

A sample of the basal diet used in this experiment was

microwave-digested (Schelkop, 1988) and analyzed for boron

content using an ICP instrument as described in Chapter 2.

The laying hens were maintained in individual wire cages

(20 x 45 x 45 cm). Feed was supplied ad libitum and water was

available to the hens for 15 minutes every two hours from 6:00

to 21:00 hr each day.

Egg production was recorded daily, and once weekly all

eggs laid for one day were weighed, specific gravity was

determined (flotation method), and albumen height was recorded

in order to calculate Haugh units. The eggshell weight was


4 Reagent grade, Fisher Scientific, Fair Lawn, NJ.







64

Table 7-1. Composition of the basal diet used in the
experiment.
%

Ground yellow corn 69.12
Dehulled soybean meal (48.5% C.P.) 19.46
Dicalcium phosphate (22.0% Ca, 18.5% P) 1.62
Ground limestone 8.69
Microingredients* .50
Iodized salt .45
DL-Methionine (98%) .11
Variables" .05

* Supplied per kilogram of diet: 6,000 IU vitamin A, 2,200 IU
vitamin D3, 2.2 mg menadione dimethylpyrimidinol bisulfite,
4.4 mg riboflavin, 13.2 mg pantothenic acid, 39.6 mg niacin,
499 mg choline chloride, .022 mg vitamin B12, 125 mg
ethoxyquin, 50 mg manganese, 50 mg iron, 6 mg copper, .198 mg
cobalt, 1.1 mg iodine, and 35 mg zinc.

Contained variable amounts of washed builders' sand and
boric acid, according to the different treatments.



calculated individually from egg weight and egg specific

gravity according to the formula5 proposed by Harms et al.

(1990). Total feed consumption was determined at the end of

each 28-day period for each pen of 10 birds.

During the second 28-day period, all females were

inseminated intravaginally for two consecutive days with .03

ml undiluted semen collected and pooled from 20 Single Comb

White Leghorn males which received no dietary boron

supplementation. Subsequently, two fertility and hatchability

trials were conducted with all eggs played in a period of five

days each. Eggs were candled on the fifth day of incubation


5 Eggshell weight = 2.0341 x egg weight -
2.1014 x egg weight / egg specific gravity








65

and eggs not showing embryonic development were broken to

determine true fertility. Hatchability was expressed as the

percentage of chicks hatched divided by the total of fertile

eggs selected at the fifth day of incubation.

Data were subjected to analysis of variance and repeated

measurements analysis. Significant differences were determined

using Duncan's multiple range test (SAS, 1985).


Results and discussion


The basal diet used in this experiment contained 15.2 ppm

boron. The concentration of boron in the municipal waters of

Florida was analyzed by Carriker et al. (1976) and found to be

always less than .1 ppm.

No significant interaction between the two periods (28

days each) and the treatments were found for any of the

variables studied. The time factor did not significantly

affect feed conversion (P=.834), egg weight (P=.254), or haugh

units (P=.745). However, the other variables were more or less

affected by the time factor (P=.060 for egg production, P=.036

for feed consumption, P=.049 for egg specific gravity, P=.019

for calculated shell weight).

For the average of the two 28-day periods boron

supplementation only affected significantly egg specific

gravity (Table 7-2). During the second period, egg specific

gravity and calculated shell weight were significantly lower

in birds fed 20 ppm boron, compared to the group fed no boron













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67

supplementation at all (Table 7-2). A more marked treatment

effect during the second period should be expected according

to the report of Pfeiffer et al. (1945) who concluded that

boron has cumulative action. However, further dietary boron

supplementation (up to 80 ppm) did not result in decreased egg

specific gravity or calculated shell weight (Table 7-2).

Therefore, the effects of boron supplementation on egg shell

quality were not resolved with the present study. Further

research is recommended, in particular the addition of higher

boron levels than the ones investigated in the present study.














CHAPTER 8
THE EFFECT OF DIETARY BORON SUPPLEMENTATION
ON BROILER BREEDERS


Introduction


Few experiments have been conducted concerning the

effects of boron on breeder performance. Lee (1989), and Lee

and Emmel (1990) applied a constant amount of boron as either

tetraborate1 or octoborate2 (1,607 or 908 g/m2/week,

respectively). These granulated boron-based insecticides were

distributed on top of the litter which resulted in their rapid

consumption by the birds. Subsequently, a significant

reduction in egg production, fertility, and hatchability

occurred.

The objective of the present experiments was to study the

effects on broiler breeder performance of supplementing

practical corn-soybean meal diets with 250 ppm boron from two

different dietary sources.








1 Na2B407.10H20, or disodium tetraborate decahydrate, or
borax.

2 Na2 803.4H20, or disodium octaborate tetrahydrate.










Materials and Methods


A flock of 300 female and 300 male Arbor Acres broiler

breeders were raised in an open-sided house to 20 weeks of

age. From 4 to 20 weeks of age the birds were maintained on a

restricted skip-a-day dietary feeding regimen to achieve the

breeder's recommended body weight. At 21 weeks of age about 50

% of the males were culled for undesirable characteristics and

the remaining birds were individually weighed and grouped by

weight. Then, the 45 males and 45 females closest in weight to

their respective means were selected and placed at random,

individually, in 40 x 60 cm cages for 16 weeks.

Experiment 1

Forty-five broiler breeder females were assigned to three

dietary treatments. Each treatment had three replicates of

five birds. The dietary treatments consisted of the

supplementation of corn-soybean meal basal diets with 0 ppm

boron (control), 250 ppm boron supplied as either boric acid3

(H3BO3, 17.50% boron), or as borax3 (sodium tetraborate,

Na2B407.10H20, 11.35% boron). All birds were individually

weighed weekly and the daily amount of feed offered was then

determined in order to adjust body weight to the breeder's

recommendations. The basal diets were formulated weekly

according to feed intake and the breeder's daily requirements

of nutrients.



3 Reagent grade, Fisher Scientific, Fair Lawn, NJ.








70

Egg production was recorded daily. At the end of each 28

day-period eggs were collected for two consecutive days and

egg weight and specific gravity were determined for all eggs,

excluding double yolk eggs. The eggshell weight was calculated

individually from egg weight and egg specific gravity

according to the formula4 proposed by Harms et al. (1990).

After the onset of egg production, all 45 females were

inseminated intravaginally twice weekly with .05 ml undiluted

semen collected and pooled from 15 broiler breeder males which

received no dietary boron supplementation. Fertility and

hatchability trials were conducted at 30, 31, and 32 weeks of

age. For all fertility trials all eggs played during a seven

day period were stored in a cooler (16.70C, 60% relative

humidity) immediately after collection. Eggs were candled on

the fifth day of incubation and eggs not showing embryonic

development were broken to determine true fertility.

Hatchability was expressed as the percentage of chicks hatched

over the total of fertile eggs selected at the fifth day of

incubation.

Experiment 2

Fourty-five broiler breeder males were assigned to the

same three dietary treatments as in Experiment 1. Each

treatment group had three replicates of five birds. T h e

males were ejaculated twice weekly and fertility trials were



4 Eggshell weight = 2.0341 x egg weight -
2.1014 x egg weight / egg specific gravity








71

conducted at 35 and 36 weeks of age. For the fertility trials

five control group females (Experiment 1) were inseminated

twice weekly starting at 33 weeks of age with semen collected

and pooled from a treatment group of males. The remaining

females were also inseminated at the same time to avoid

differencial handling of the treatment groups. The fertility

trials were conducted as described in Experiment 1.

At 37 weeks of age semen was evaluated for total

spermatozoal cell concentration and percentage of damaged

spermatozoal cells using a fluorometric assay (Bilgili and

Renden, 1984). The equation5 to estimate the stained

spermatozoal cell concentration from the intensity of

fluorescence was determined by Bootwalla (1990, unpublished

data).

Data were subjected to analysis of variance and

significant differences were determined using Duncan's

multiple range test (SAS, 1985).


Results and discussion


No significant differences were found in Experiment 1 for

age at 5% egg production, average egg production, final body

weight (Table 8-1), egg weight, egg specific gravity, or

calculated shell weight (Table 8-2).



5 Stained spermatozoal cell concentration = 1.4786 +
4.0667 x Intensity of fluorescence.
Determined by regressing intensity of fluorescence on direct
count of stained spermatozoal cells.


















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73

Fertility and hatchability increased with age and were

highest for the control group at each fertility trial (data

not presented). Average hatchability for the boron-

supplemented group was significantly lower than that of the

control birds (Table 8-1). This reduced hatchability agrees

with the results of Lee (1989), and Lee and Emmel (1990).

In Experiment 2 average fertility, average hatchability,

total concentration of spermatozoal cells, and final body

weight were not significantly different. However, percent

damaged spermatozoal cells of the males fed boric acid was

higher than that of those receiving no dietary boron

supplementation (Table 8-3). The increase in damaged

spermatozoal cells of the males fed borax was almost

significant (P=.051).

No evidence was found in either experiment to conclude

that the effects of dietary boron supplementation on the

measured variables differed according to source of boron.

These data demonstrate the detrimental effects of 250 ppm

supplemental boron in the male and female broiler breeder

diet. There are various factors that could result in even

poorer reproductive performance of breeder flocks fed boron in

comparison with the treated birds in the present experiment:

1) The effect of boron supplementation was studied

separately in males and females; therefore, the negative

effects of feeding both sexes with boron could be even greater

and needs further investigation.








74

Table 8-2. Characteristics of eggs from broiler breeder
females fed a corn-soybean meal diet supplemented with 0
(control) or 250 ppm boron supplied as either boric acid or
borax (Experiment 1).

Dietary boron Egg Egg specific Shell
Treatment weight gravity weight*
ppm source (g) (1.0---) (g)


0 Control 65.1 764 5.3
250 Boric acid 66.0 799 5.8
250 Borax 63.2 797 5.6

Pooled SEM .97 13.3 .18

* Calculated from the following formula (Harms et al.,
1990): Shell weight = 2.0341 x egg weight -
2.1014 x egg weight / egg specific gravity

ab Values within columns followed by different letters are
significantly different (P<.05).



2) The frequency and dosage of the inseminations were

designed to ensure that the availability of spermatozoal cells

was not a limiting factor. In Experiment 2, the fertility and

hatchability observed were excellent. However, under practical

conditions the three-fold increase in dead spermatozoal cells

could lead to poor reproductive performance.

3) The negative effects of boron could be greater than those

observed in this study if boron supplementation continued for

a longer period of time than in the present study since

Pfeiffer et al. (1945) concluded that boron has a cumulative

action.

4) The current vendors' recommendation for the application

of borates to control black beetles in commercial situations

are 159g of boron/9.3m2/wk, applied under or mixed with the

















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76

litter. Based on a density of 6 birds per m2, this dosage is

approximately equivalent to 4,068 ppm boron if entirely

consumed. Lee and Emmel (1990) found that breeders are able to

consume most of this amount if granulated insecticides are

applied on top of the litter.

Therefore, after considering the results of the present

experiment, as well as those of Lee and Emmel (1990), caution

is recommended when applying borate products to the litter.














CHAPTER 9
SUMMARY





Boron has met the following criterium of essentiality:

Its deficiency impairs biological functions from optimal to

suboptimal as found in plants (Honningstad, 1935; Oregon

Agricultural Experiment Station, 1941), rats (Skinner and

McHargue, 1945), heifers (Green and Weeth, 1977), humans

(Nielsen et al., 1987), and sheep (Brown et al., 1988).

Boron has also been found to be essential for some

categories of poultry. Hunt and Nielsen (1982), and Elliot and

Edwards (1990) discovered beneficial effects of adding 3 ppm

boron to purified diets for broiler chicks grown to three

weeks of age. However, Elliot and Edwards (1989) found that

supplementing 20, 40, or 80 ppm boron to a practical diet had

no significant effect on any variable studied. Perhaps the

boron content of this practical diet was enough to meet the

chick's boron requirement. The boron content of soybean meal

alone would normally account for more than 5.6 ppm boron in a

typical corn-soybean meal practical poultry diet (Chapter 2).

Another concentrated (up to 500 ppm) dietary source of boron

is calcium phosphate (Shuler, 1988, Grand Forks Human

Nutrition Research Center, Grand Forks, ND, personal








78

communication). Boron has been proven essential only when

feeding purified diets. Very few experiments were conducted in

this area, therefore, it became important to determine if

boron supplementation is necessary when feeding practical

diets.

Additional sources of boron in commercial poultry

production are borate-based insecticides which are used as

litter treatments. These products diminish fertility and

hatchability (Lee, 1989). High dosages of boron (i.e. 1,400

ppm) could also affect chick body weight as reported by Roe et

al. (1972). Therefore, conducting research regarding the

effects of feeding different levels of boron also becomes

important.

Nine experiments were conducted to study the effects of

boron supplementation of practical corn-soybean meal diets for

poultry: five experiments were conducted with broiler chicks

grown to 21 days in batteries, one experiment was conducted

with broilers grown to 49 days on litter, another experiment

was conducted with laying hens, and two experiments were

conducted with broiler breeders.

Two of the experiments were conducted with the objective

of determining if boron is required by broiler chicks in

amounts above those furnished by the ingredients in a

practical corn-soybean meal diet as well as to determine if

dietary addition of moderate amounts of boron (up to 300 ppm)

would be detrimental to broiler performance. A total of 432








79

day-old broiler chicks were placed in batteries and fed ad

libitum for 21 days. Male body weight of chicks fed a basal

diet containing 9.4 ppm boron was lower than that of chicks

fed the same basal diet supplemented with 5 ppm boron.

However, supplementing a basal diet containing 15.6 ppm boron

with different amounts of boron (60, 120, 180, 240, 300 ppm)

did not result in a significant increase in body weight. Body

weight and feed intake were depressed when birds were

supplemented with more than 120, but especially over 240 ppm

boron in the diet. This tendency was slightly more marked in

the case of the male as compared with female chicks. The best

feed conversion was achieved when boron was supplemented to

the diet at 120 ppm. An index of efficiency of mineral

utilization improved with the addition of boron to the diets.

Percent tibia ash was significantly higher only when boron was

supplemented at the highest level (300 ppm). The correlation

between boron supplementation and tissue (breast muscle,

liver) contents of boron was high (r=.89, r=.96,

respectively). Therefore, continual consumption of high levels

of boron will lead to tissue accumulation.

One experiment was conducted with the objective of

comparing the effects of the addition of 30 or 60 ppm boron

from three different dietary sources (boric acid, boron

trioxide, or borax) to broiler chick diets. A total of 420

day-old broiler chicks were placed in batteries and fed ad

libitum for 21 days. The basal diet used in this experiment







80

contained 18.3 ppm boron. Feeding 30 or 60 ppm boron, supplied

by either dietary source, resulted in average body weights

numerically equal to or greater than the control group but

these differences were not statistically significant.

Another experiment was conducted to determine if the

effects of 60 ppm boron supplementation depended on the levels

of Vit. D3 or on the levels of calcium and phosphorus

utilized. A total of 432 day-old broiler chicks were placed in

batteries and fed ad libitum for 21 days. The basal diet used

in this experiment contained 22.3 ppm boron. Feeding various

levels of Vit. D3, calcium and phosphorus affected chick

performance. However, the interaction between boron and

calcium and phosphorus only approached significance (P=.056)

for tibial dyschondroplasia score. Other variables were not

affected by the addition of 60 ppm boron to the diets.

Another experiment was conducted to determine the effects

of 0 and 20 ppm boron supplementation when feeding diets

containing no supplemental salt for the first seven days of

age. A total of 144 day-old male broiler chicks were placed in

batteries and fed ad libitum for 21 days. The basal diet used

in this experiment contained 21.9 ppm boron. Unexpectedly,

birds in the salt withdrawal treatment had lower tibia ash

when fed diets with 20 ppm boron supplementation as compared

to the birds fed diets containing no boron supplementation. On

the other hand, addition of boron to the salt withdrawal

treatment diminished the tibial dyschondroplasia score at








81

three weeks of age. However, this lower score could be related

to the lower tibia weight (although not significantly lower)

of those birds since the severity of tibial dyschondroplasia

was dependent on bird age.

One experiment was conducted to study the economics of

boron supplementation, to determine if the addition of

different amounts of boron would result in toxicity, and to

determine whether or not additional riboflavin in the diet

would counteract the possible toxic effects of boron. A total

of 672 day-old broiler chicks were housed in litter pens to 49

days of age. The basal diet used in this experiment contained

22.3 ppm boron. The lowest male, female, and average body

weights at 21 and 49 days of age were observed for the birds

consuming diets with 320 ppm of boron supplementation. The

addition of riboflavin did not alleviate the body weight

depression which resulted from boron supplementation. However,

when 17.6 ppm riboflavin was added in combination with 320 ppm

boron, at 49 days of age feed consumption was the lowest and

feed conversion was the best of all other treatment groups.

Dietary boron supplementation of 20 or 80 ppm resulted in

higher profits compared with supplementation of either 0 or

320 ppm boron.

Another experiment was conducted to study the effects of

supplementing practical corn-soybean meal laying hen diets

with various concentrations of boron (0, 20, 40, and 80 ppm).

A total of 280 Single Comb White Leghorn hens were kept in








82

cages and fed the experimental diets ad libitum for two 28 day

periods. The basal diet used in this experiment contained 15.2

ppm boron. Addition of 40 or 80 ppm boron did not affect any

variable studied. During the second period egg specific

gravity and calculated shell weight were significantly lower

in birds fed 20 ppm boron compared to the group fed no boron

supplementation.

Two experiments were conducted to study the effects of

supplementing practical corn-soybean meal broiler breeder

diets with 250 ppm boron from two different sources (boric

acid or borax). A total of 90 broiler breeders were housed in

individual wire cages and fed the experimental diets from 21

to 37 weeks of age. Females fed boron from either source had

numerically lower fertility and significantly lower

hatchability in each of the three fertility trials. Males fed

boron produced three times more damaged spermatozoal cells

compared with the control birds.














GLOSSARY


B boron

b bird

C centigrade

cts cents

Ca calcium

cm2 squared centimeters

C.P. crude protein

d day

g grams

ICP inductively coupled plasma

IU international units

Kg kilograms

m2 squared meters

mg milligrams

ml milliliters

mm millimeters

nm nanometers

P phosphorus, or probability

ppm parts per million

SEM standard error of the mean

SAS Statistical Analysis System Institute, Inc.

USDA United States Department of Agriculture

83









84

Vit. D3 cholecalciferol

wk week














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