Group Title: effect of diethylstilbestrol and methyltestosterone on the growth, carcass characteristics, and nitrogen retention of growing swine /
Title: The Effect of diethylstilbestrol and methyltestosterone on the growth, carcass characteristics, and nitrogen retention of growing swine
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Title: The Effect of diethylstilbestrol and methyltestosterone on the growth, carcass characteristics, and nitrogen retention of growing swine
Physical Description: 158 leaves : ill. ; 28 cm.
Language: English
Creator: Lucas, Ernest William, 1942-
Publication Date: 1970
Copyright Date: 1970
Subject: Hormones -- Research   ( lcsh )
Animals -- Physiology   ( lcsh )
Plant growth promoting substances   ( lcsh )
Animal Science thesis Ph. D
Dissertations, Academic -- Animal Science -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Thesis: Thesis (Ph. D.)--University of Florida, 1970.
Bibliography: Bibliography: leaves 149-156.
Additional Physical Form: Also available on World Wide Web
Statement of Responsibility: by Ernest William Lucas.
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097726
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000407264
oclc - 24664467
notis - ACF3556


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The Effect of Diethylstilbestrol and Methyltestosterone on

the Growth, Carcass Characteristics, and Nitrogen

Retention of Growing Swine





I wish to extend thanks to my major professor, Dr. H. D.

Wallace, for guidance and advice during the course of the investi-

gation, as well as to Dr. Herb Brown of Eli Lilly and Company for

supplying the hormone material and participating in the taste

panel. The assistance of Drs. William Mendenhall and John Cornell

in statistical analysis is also gratefully acknowledged. wish

also to thank Dr. A. Z. Palmer and Roger West for their assistance

in obtaining carcass data, and Bill Stradtmann for help with the

laboratory analyses. The assistance of Mike Demaree and Jim

Standish, fellow graduate students, was indispensable during the

field work and collection of data.

Special and deepest appreciation is extended to my wife, Barbara,

for her encouragement and for typing the manuscript and drawing the



ACKNOWLEDGEMENTS.......................... .................... 11

LIST OF TABLES................................................. v

LIST OF FIGURES...............................................** VI

ABSTRACT .......................... ............................ x

INTRODUCTION .................................................. 1

REVIEW OF LITERATURE ........................................... 3

The Effects of Sex on the Growth and Carcass
Quality of Swine. ............................ .............. 3

Sex Odor in Pork............................................ 6

The Effects of Estrogens on the Growth and
Carcass Quality of Swine..................................... 12

The Effects of Androgens on the Growth and
Carcass Quality of Swine ................................... 19

The Effects of Combinations of Androgens and
Estrogens on the Performance and Carcass
Quality of Swine........................................... 24

The Effects of Androgens on Protein Anabolism
in Animals.................................................. 28

The Effects of Diethylstilbestrol on Protein
Anabolism in Animals........................................ 30

The Mechanisms of Anabolic Action of Androgens
and Diethylstilbestrol..................................... 32

EXPERIMENTAL................................................... 35

General Objectives ......................................... 35

General Experimental Methods................................. 35

Analytical Methods......................................... 40

i i


EXPERIMENTAL (continued)

Statistical Methods........................................ 45

Experiment 178-A........................................... 46

Experiment 178-B............................................ 49

Experiment 178-C........................................... 53

Experiment 178-D........................................... 55

Experiments 178-E and F.................................... 58

GENERAL DISCUSSION ............................................ 61

The Effects of Hormone, Protein, and Sex on the
Feedlot Performance of Growing-Finishing Swine.............. 61

The Effects of Hormone, Protein, and Sex on the
Carcass Characteristics of Swine........................... 64

The Effects of DES + MT on the Nitrogen Retention
of Growing-Finishing Swine.................................. 70

The Effects oF DES + MT on the Excretion of Urinary
17-ketosteroids in Swine.................................... 72

General Comments............................................. 73

SUMMARY AND CONCLUSIONS........................................ 77

APPENDIX I: Tables............................................ 80

APPENDIX II: Figures.......................................... 110

LITERATURE CITED............................................... 149

BIOGRAPHICAL SKETCH ........................................... .157


Table No. Page


1 Composition of diets................... 81

2 Calculated analysis of diets........... 81

3 Trace mineral premix................... 82

4 Vitamin premix......................... 82

5 Dry matter and protein % of diets...... 82

6 Code for marbling score, 1. dorsi...... 83

7 Code for color score, 1. dorsi ......... 83

8 Code for firmness score, 1. dorsi...... 84

9 Code for boar odor and flavor.......... 84


10 Experimental design.................... 85

11 Feedlot performance summary............ 85

12 Feedlot performance t test............. 86

13 Summary of responses ................... 87

14 Analysis of variance................... 88

15 Analysis of variance................... 89

16 Analysis of variance ..............".... 90

LIST OF TABLES (continued)

Table No. Page


17 Experimental design, growing phase..... 91

18 Experimental design, finishing phase... 91

19 Feedlot performance means, growing
phase. 92

20 Analysis of variance................... 92

21 Summary of responses................... 93

22 Analysis of variance................... 94

23 Analysis of variance................... 95

24 Analysis of variance................... 96


25 Experimental design.................... 97

26 Summary of responses................... 97

27 Analysis of variance................... 98

28 Analysis of variance................... 98

29 Analysis of variance................... 99

30 Analysis of variance.................... 99

31 Analysis of variance................... 100


32 Experimental design.................... 100

33 Summary of responses................... 101

34 Analysis of variance................... 102

35 Analysis of variance................... 103

36 Analysis of variance................... 104

37 Analysis of variance................... 105

LIST OF TABLES (continued)

Table No.










Experimental design.................... 106

Suimary of responses ................... 106

Analysis of variance................... 107

Analysis of variance................... 107

Analysis of variance................... 108

Analysis of variance................... 108

Significant effects in 4 trials........ 109


Figure No. Page


1 PxHxS interaction: dressing %.......... I11

2 PxHxS interaction: % lean cuts......... 112

3 Sex effect: % ham....... ........... 113

4 HxS interaction: % loin................ 114

5 Protein effect: % picnic............... 115

6 Hormone effect: % picnic............... 116

7 Hormone effect: % butt................. 117

8 PxS interaction: % butt................ 118

9 Protein effect: backfat thickness...... 119

10 Hormone effect: backfat thickness...... 120

11 Protein effect: loin eye marbling..... 121

12 Hormone effect: loin roast aroma and
flavor..... 122


13 Sex effect: daily gain................ 123

14 HxS interaction: daily feed........... 124

15 Hormone effect: feed/gain.............. 125

16 PxS interaction: dressing % .......... 126

17 HxS interaction: % lean cuts.......... 127

18 HxS interaction: % loin............... 128

19 PxH and HxS interaction: backfat
thickness. 129

LIST OF FIGURES (continued)

Figure No. Page


20 PxHxS interaction: carcass length..... 130

21 Sex effect: loin eye firmness......... 131

22 *roae Cff 1- --Cz- -
flavor.... 132


23 HxS interaction: daily gain............ 133

24 Sex effect: daily feed................ 134

25 Hormone effect: daily feed............ 135

26 Hormone effect: feed/gain............. 136

27 Hormone effect: % lean cuts........... 137

28 HxS interaction: % ham................ 138

29 Hormone effect: % picnic.............. 139

30 Hormone effect: % butt............... 140

31 Hormone effect: backfat thickness..... 141

32 Sex effect: loin tenderness........... 142

33 Hormone effect: pork chop aroma and
flavor... 143

34 Hormone effect: loin roast aroma and
flavor... 144

35 Sex effect: 1. dorsi % dry matter..... 145

36 Hormone effect: 1. dorsi % protein.... 146

37 Sex effect: 1. dorsi % fat............ 147

38 Hormone effect: 1. dorsi % fat........ 148

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



Ernest W. Lucas

June, 1970

Chairman: H. D. Wallace
Major Department: Animal Science

Experiments were conducted to determine the effects of a combi-

nation of 2.2 mg each of diethylstilbestrol and methyltestosterone

(DES + MT) per kg of feed on the feedlot performance, carcass charac-

teristics, and nitrogen retention of growing-finishing swine. The

interrelationships between hormone supplementation and dietary protein

level and sex were also investigated. A total of 6 trials, involving

205 crossbred pigs, were conducted. Of these, 4 were feeding and car-

cass experiments and 2 were metabolism trials. Practical corn-soybean

meal rations with 12, 14, or 16 percent protein were fed with and

without DES + MT to growing-finishing barrows and gilts.

Hormone supplementation caused a decrease in average daily gain

and average daily feed consumption, but improved feed conversion effi-

ciency. Protein level did not significantly affect feed intake, feed

efficiency, or rate of gain. Barrows ate more feed and gained faster

than gilts.

Carcass leanness was markedly improved by hormone supplementation.

Evidence of this was seen in an increased percentage of lean cuts,

both individually and as the 4 lean primal cuts, in pigs fed DES + MT.

There was also a decreased backfat thickness and increased carcass

length due to hormone supplementation. In addition, pigs fed higher

protein lpvelq were leaner than those fed Ic.waer protein levels. Gilts

were leaner than barrows.

Carcass subjective measurements were not affected by any treat-

ment. There was a significantly increased incidence of boar odor and

flavor in the meat of pigs fed DES + MT. This boar odor markedly

decreased the eating quality of meat of treated pigs in some cases.

Chemical composition of meat was significantly but not consistently

affected in 2 trials by DES + MT.

Nitrogen retention was not enhanced by feeding DES + MT in 2 ex-


Excretion of 17-ketosteroids in urine was significantly but not

consistently affected by hormone supplementation.

Interactions of hormone supplementation with both sex and protein

level were observed; these obscured some main effects. Interactions

affecting average daily gain, average daily feed intake, dressing

percentage, yield of lean cuts, average backfat thickness, average

loin eye area, and carcass length were observed.

The mode of action of DES + MT in improving carcass leanness was

not clear. The effects of hormone supplementation were not consistently

manifested in all trials, although there was in general a trend toward

decreased feed intake and rate of gain, increased feed efficiency, and

improved carcass leanness due to DES + MT. Although DES + MT can be

of significant benefit in improving feed conversion efficiency and car-

cass leanness, these benefits may be partially offset by the presence

of boar odor and flavor in the meat of some treated pigs.


The use of feed additives and chemotherapeutics in animal rations

for the purpose of improving performance and production is a topic of

continuing interest in the nutrition field. Experiments have been

conducted with all species of domestic livestock for the purpose of

developing, testing, and evaluating various chemotherapeutics for use

in livestock rations. Many of these compounds are in general use


Recent trends in consumer preference have focused attention on

the need for animals which will gain efficiently and produce lean,

meaty carcasses without excess fat trim.

About 20 years ago it was discovered that the addition of cer-

tain estrogenic substances to the rations of beef cattle in the feed-

lot produced beneficial responses in these cattle. Among the effects

were improved feed efficiency and gains, heavier muscling, increased

nitrogen retention and decreased fat deposition. It has become

standard practice to feed or implant this material, diethylstilbestrol,

to finishing cattle nearly everywhere in the U.S.

The advent of diethylstilbestrol feeding in cattle has sparked a

whole field of research involving hormone feeding, using most species

of domestic animals. Although the merits of diethylstilbestrol are

proven in the case of ruminants, the responses in monogastric species

have been somewhat varied. Several other estrogenic substances have

been investigated as potential feed additives, as well as numerous

androgenic compounds. Recently, work using combinations of estrogen

and androgen has been done.

Research with hormones as chemotherapeutics for swine has been

conducted since the early 1950's, with varying results. Evidence pro

and con has been collected for several different hormones, including

diethylstilbestrol and methyltestosterone, the most widely used estro-

gen and androgen, respectively. Recent work indicates that a combina-

tion of these two compounds fed to growing-finishing swine is more

effective in stimulating efficiency, carcass quality, and leanness

than either one alone.

The purpose of this study was to investigate the effects of a di-

etary combination of diethylstilbestrol (DES) and methyltestosterone

(I)T), fed at 2.2 my each per kg of feed, on the growth, carcass charac-

teristics, and nitrogen retention of growing-finishing pigs.


The Effects of Sex on the
Growth and Carcass Quality of Swine

Sex has been recognized for many years as a factor which affects

the performance of meat animals. Differences in growth, efficiency,

and carcass characteristics between the genders are common in most

species. Swine are prone to show sex differences in performance and

carcass quality.

Blair and English (1965) reported on an experiment designed to

measure sex differences in growth and carcass quality in growing-

finishing pigs. These workers fed boars, gilts, and barrows on a

similar ration from weaning to market weight and measured carcass

parameters and feedlot performance. They reported significant differ-

ences among sexes in the various standard carcass parameters. Boars

had significantly less backfat than either barrows or gilts. In addi-

tion, boars and gilts showed a significantly larger loin eye area than


Wallace (1965) reviewed the effects of sex influences (barrows vs.

gilts) on finishing swine and concluded that gilts gained more slowly

but more efficiently than barrows, and that gilts were superior to

barrows in all aspects relating to carcass leanness.

Kolaczyk and Kotik (1966) compared muscle properties of barrows

and gilts. The meat of gilts had a significantly higher percentage of

moisture than that of barrows. Barrows exhibited significantly more

fat in the meat than gilts. No significant difference was observed

between barrows and gilts for nitrogen content of lean meat. Gilts,

however, had a significantly higher myoglobin level in the muscle

than barrows; as a result, the meat of gilts was significantly darker

than that of

Hale and Southweli (1967) measured differences in swine perfor-

mance and carcass characteristics due to dietary protein, sex, and

breed. They fed 60 weanling pigs in a 3 x 2 x 2 factorial experiment

to study effects of level of protein sequence (18 15%; 16 13%;

and 14 11%), sex (barrow and gilt), and breed (Duroc and Hampshire),

on performance and carcass traits of growing-finishing swine. Sex

differences were noted by these authors. They reported that barrows

gained significantly faster than gilts, but that gilts had a signifi-

cantly higher dressing percentage than barrows. In addition, the car-

casses of gilts were significantly longer, had less backfat, larger

loin eye area, and a higher percentage of lean primal cuts than those

of barrows.

Hale, Johnson, and Warren (1968) studied the effect of season,

sex, and energy level on performance and carcass traits of pigs. They

used 80 weanling Duroc barrows and gilts, and reported that barrows

consumed significantly more feed per day and needed more feed per unit

of gain than gilts. Gilts, however, yielded carcasses that were sig-

nificantly longer, leaner, had a larger loin eye area, and had a higher

percentage of lean primal cuts than barrow carcasses.

Swierstra and Rahnfeld (1968) studied growth, carcass measure-

ments, and sexual development of partially or completely castrated pigs.


They reported no differences-in rate of gain, age at slaughter, dress-

ing percentage, ham weight, loin eye area, average backfat thickness,

or carcass length between pigs partially castrated by Baiburtcjan's

method and pigs completely castrated.

Wong, Boylon, and Stothers (1968) performed an experiment to

study differences in performance and carcass traits of swine due to

sex and dietary protein level. One group of pigs containing equal num-

bers of boars, barrows, and gilts with an initial average weight of

22.5 kg was given a growing ration (17% protein) until slaughter at

an average weight of 88.6 kg. A similar group of pigs received the

growing ration to a body weight of 50 kg and then a finishing ration

(13% protein) until slaughter. No differences due to protein were

observed, but significant differences between sexes were found for

average daily gain and feed per unit of gain. Boars exceeded barrows

by 7 percent and gilts by 5 percent in average daily gain. Boars re-

quired 16 percent less feed per unit of gain than barrows. Gilts

exceeded boars and barrows in loin eye area. Both boars and gilts were

superior to barrows in percent lean in the ham face.

On the basis of the previously cited experiments, it seems reason-

able to conclude that there is a real sex difference in performance and

carcass quality in swine. When only performance and carcass objective

measurements are considered, boars rank superior to gilts, and gilts

rank superior to barrows. In light of the differences observed between

the sexes in performance and carcass traits, it seems logical to assume

that the cause of these differences might be due to the presence or

absence of the natural sex hormones produced'in the gonads.

Sex Odor in Pork

Castration of male farm animals is a practice which is nearly as

old as the domestication of animals. Benefits originally sought were-

those of greater tractability in work animals. Physiological changes

and ensuing material developmental changes occur in animals following

castration. The effect of castration on growth, feed efficiency, car-

cass traits, and meat quality rust be weighed against the inherent

advantages in growing uncastrated males. Literature previously cited

shows that there might be an economic advantage, in addition to

breeding and selection advantages, in feeding intact boars.

In swine, however, the phenomenon known as "sex odor," "boar

odor," or "taint" occurs to some degree in the fat and meat of intact

males. Martin (1969), in a review of the sex odor problem in pork,

documents cases of sex odor in boars as far back as 1936. This odor

or flavor has caused a discrimination by packers and consumers against

the meat of intact male swine. In spite of the advantages in perfor-

mance and carcass traits which boars exhibit, it is not economically

feasible to feed boars.

In his review, Martin (1969) notes that comprehensive studies

of carcasses of pigs of all sexes, conducted at commercial slaughter-

houses, showed that 17 percent of all hogs, regardless of sex, exhibit-

ed medium to strong sex odor. The problem is not confined to boars.

This observation is corroborated by Wil liams, Pearson, and Webb (1963),

who studied the incidence of sex odor in boars, sows, barrows, and

gilts. Incidence of sex odor was studied using fat samples from the

flank area or ham facing of 79 boars, 78 sows, 86 barrows, and 96 gilts.

Results indicated that the occurrence of sex odor was largely, but not

exclusively, dependent on the sex of the animal. Boars were found to

have 64 percent incidence of sex odor, significantly higher than any

other group tested. No significant differences could be found between

the percent incidence of sex odor in sows, barrows, and gilts, which

were found to have 1 percent, 5 percent, and 5 percent incidence,


Blair and English (1965) reported significantly more boar odor in

boar meat and fat than in barrow or gilt meat and fat, but were unable

to demonstrate any differences in flavor.

Charette (1961) indicated little or no undesirable odor in boar


Martin, Freden, and Stothart (1968) evaluated the quality of

cooked pork from 144 pigs consisting of an equal number of barrows,

boars, gilts, and ridglings which ranged from 87 to 93 kg live weight

at time of slaughter. Ham steaks, prepared and cooked by a standard

procedure, were evaluated for cooking aroma, tenderness, juiciness,

texture, flavor, and overall preference by a panel of 6 trained judges.

Samples were scored on a 1 to 10 hedonic scale with 10 representing the

most favorable score. For tenderness and texture, the samples from

boars ranked highest, followed by gilts, barrows, and ridglings. All

sex differences were significant for these two characteristics. Rank-

ing for overall score and overall preference by judges was in this same

order. Samples from barrows and ridglings scored higher for cooking

aroma than samples from boars and gilts, although only 3 boars and 1

gilt were judged unacceptable. However, the authors noted that aroma

was not highly correlated with flavor, and samples which scored low on

aroma were often quite acceptable for flavor.

Craig and Pearson (1959), in a preliminary study on sex odor in

pork, reported that sex odor was strongest in the parotid gland, fat,

testicles, penis, and preputial diverticulum. The study was conducted

on the tissues of an 18 month old boar. They noted that fat or lean

with intramuscular fat produced boar odor when heated to the boiling

point in water. A barrow control failed to produce boar odor upon

heating. Ether extraction of the freeze-dried lean tissue produced an

extract which appeared to contain the odor component, which the extrac-

ted lean did not. Ether or carbon tetrachloride extracted fat did not

give off sex odor when heated. This led the authors to conclude that

sex odor in pork is found only in the fatty tissues and that the odor-

contributing elements may be separated from the fat by a selective

extraction process.

In another study, Craig (1960) was unable to detect sex odor in

any aqueous distillation condensates of boar fat, although a strong

sex odor was evident in the rat prior to distillation. This further

demonstrated the lipophilic nature of the sex odor component. Fat

from boars did not differ significantly from that of barrows with re-

gard to nitrogen content.

Craig (1961), in a dissertation abstract, reported that the

odor component of boar fat was not readily voldtilized below 100" C.

lie was unable to isolate the component from any solvent fraction by

collecting distillates.

Craig, Pearson, and Webb (1962) reported the findings of a series

of experiments to fractionate the components responsible for sex odor

in pork. They noted that sex odor was produced when fat, lean with

fat in it, and most organs from a boar were heated in a skillet or in

hot water. Odor volatilized most greatly at 100 to 1080 C, but was

not entirely absent at body temperature. The sex odor component was

found to be water insoluble, ether soluble and definitely associated

with the fatty tissues of boars. The odor was absent in reconstituted

moisture-free, fat-free lean tissue. Distillation methods were

regarded as unsuccessful in collecting sex odor components in any

recognizable form. No differences in distillates of boar and barrow

fat were detected by heat tests or gas chromatography. Cold saponi-

fication of boar fat yielded a small amount of unsaponifiable matter

which produced a concentrated, permeating sex odor on heating. The

authors concluded that the agents responsible for sex odor are located

in the unsaponifiable fraction of boar fat. Cholesterol and squalene

were found in this fraction of both boar and barrow fat, but sex odor

was not produced when either of these compounds was heated.

Patterson (1566) isolated large amounts of para-cresol, a metabo-

lite of tyrosine, from the phenolic fraction of boar preputial fluid.

It was not concluded that para-cresol was directly responsible for the

characteristic sex odor of heated boar fat, although it does contribute

significantly to the odor of the live boar and its immediate environ-


In a second paper, Patterson (1968a) identified a derivative of

the male sex hormone as the odor component in boar fat. This substance,

5-a-androst-16-ene-3-one, is a lipophilic ketone, and is found in the

fat of mature boars. This compound was found to have the empirical

formula C19H280, differing from the male hormone testosterone only by

a single oxygen atom and from androsterone by the elements of a mole-

cule of water. The author concluded that the source of the odor com-

ponent was a metabolite of the male sex hormones.

Patterson (1986b) later shed more light on the pathway of forma-

tion of the boar odor component. A musk odor compound, 3-a-hydroxy-5-

a-androst-16-ene, was isolated from the submaxillary salivary glands

of all boars tested, but not from the glands of barrows or gilts.

This secondary alcohol is a musk odor compound distinctly different

from the ketone previously isolated from boar fat. The alcohol was

successfully oxidized in vitro to the ketone, and the odor changed

from a musk to a boar taint. Since male sex hormones, the musk odor

alcohol, and the boar odor ketone all are so similar in structure, the

author concluded that both odor compounds were under testicular con-

trol. A pathway by which testosterone could be transformed to 3-0-

hydroxy-5-a-androst-16-ene was suggested. The B epimer also possesses

musk odor activity, but the a epirnr is much stronger. It may be that

epir-erization of the B compound to the a epimer occurs, since salivary

glands of boars contained almost exclusively the a substance.

Patterson (1968b) suggested an interesting hypothesis as to the

means of incorporation of boar odor into the fat of boars. He observed

that it was possible to detect the presence of the musk odor alcohol

in the submaxillary glands of young boars before the boar odor ketone

appeared in the gland or fat, and that the detection of the ketone,

as well as the alcohol, in the salivary glands of older boars shows

that the ketone is formed by the oxidation of the alcohol at a later

stage of maturity. He noted that the concentration of androstenol was

relatively high in the salivary gland of mature boars compared to the

androstenone concentration, but that in depot fat the opposite was

true. This observation led him to suggest that the submaxillary sali-

vary gland is either the site of formation of the androstenol, or that

it acts as a reservoir for the substance, presumably extracting it

from the bloodstream. He also noted that musk odors are known sex

attractants and that either androstenol or androstenone in the saliva

may act in this capacity. The sexual behavior of boars and sows

suggests an attractant of some kind present in the head of the boar.

Since the saliva was found to possess the odor of 5-a-androst-16-ene-

3-one, ingestion of the ketone in the saliva will result in its incor-

poration into the body as a result of the normal digestive process.

Because of its ketone structure, deposition in adipose tissue will

occur preferentially to other tissues. The hydrophilic alcohol, on

the other hand, will be eliminated from the body in:its normal water-

soluble state. This would explain the presence of the androstenone

but absence of androstenol in the depot fat of mature boars.

Weir et al. (1962) reported on a study of the composition and

organoleptic properties of pork chops as affected by cooking procedures.

They noted an increased percentage of fat on a dry weight basis for

the lean of cooked chops over the lean of raw chops. This was due to

migration of external fat into the meat during cooking. The authors

suggested that the phenomenon may be of some significance in the odor,

flavor, and texture of cooked meat.

From the evidence presented in the papers previously cited several

conclusions regarding sex odor may be drawn.

Research has shown that boar odor appears to be sex-limited and

associated with the presence of a ketone derivative of testosterone,

found in the fatty tissues of tainted carcasses.

All factors affecting the incidence of boar odor are not yet known,

but stage of maturity is very important. Incidence of boar odor is

high in mature boars and very low or nil in boars slaughtered at 70 kg

live weight or in boars which reach conventional slaughter (90 kg) at

a young age.

The assumption that all boar carcasses contain taint is invalid,

as well as the assumption that all barrow and gilt carcasses do not

contain taint.

The Effects of Estrogens on the
Growth and Carcass Quality of Swine

Diethylstilbestrol (DES), a synthetic estrogen, came into vogue

as a feed additive for cattle in the late 1940's and early 1950's.

During this period a number of workers began feeding or implanting

estrogens and other humoral substances in several species of domes-

tic livestock in an attempt to realize benefits similar to those ob-

tained in cattle supplemented with DES.

Woehling et al. (1951) were among the first workers to study

the effects of DES on swine. These workers fed 42 growing-finishing

pigs on a standard ration. Treatment was applied by subcutaneously

implanting 2 lots of 7 pigs each with 12 rg of DES at the start of

the experiment and again at 12 weeks. Pigs averaged 19.5 kg at the

start of the experiment and were slaughtered as they reached 95 kg.

Average daily gain, average daily feed intake, feed required for each

unit of gain, dressing percentage, carcass length, weight of ham,

loin eye area, and backfat thickness were among the characteristics

studied. These workers reported no significant differences due to

DES in any of these parameters.

Oinusson, Klosterman, and Buchanan (1951) implanted 12 or 25 mg

of DES in barrows and gilts. Average initial weight was 20 or 45 kg.

These workers did not observe any response in rate of gain or carcass

parameters due to DES. They did report, however, that DES implanted

hogs required 5 to 14 percent less feed per unit of gain than control


Pearson et al. (1952) conducted 3 experiments to determine the

effects of DES implants on average daily gain, feed efficiency, and

carcass characteristics of growing-finishing swine of different sexes.

Barrows, gilts, and boars weighing 16 or 42 kg initially were sub-

cutaneously implanted with DES. Level of dosage used was 25 mg

initially, 25 mg again at I month, and 50 mg at 2 months. These

workers reported no significant difference in rate of gain of barrows

or gilts caused by implanting DES, but there was a growth depression

in young implanted boars. No effect on feed efficiency due to DES was

observed. No differences in backfat thickness, carcass grade, or ten-

derness were apparent. DES had little or no influence on acceptability

ratings of pork loin roasts and did not appear to increase the eating

qualities of boar meat.

Beeson et al. (1955) conducted an investigation with barrows and

gilts weighing 20 kg initially, and fed a practical ration containing

DES in a quantity to supply 2 mg per animal per day. The treatment

did not improve growth rate or feed efficiency. There was a trend

toward leaner carcasses in the pigs fed DES, but no significant dif-

ferences were observed.

Taylor et al. (1955) studied the effects of orally administered

sciibescroi at levels of 0, 22, 44, 88, i76, 352, 704, 1408, or 28i6

pu of DES per kg of feed on the growth, carcass traits, and organ

development of growing-finishing pigs. A total of 120 pigs averaging

15 kg initially was finished to a terminal weight of 91 kg. No

differences in average daily gain or feed conversion were observed due

to feeding DES. Carcass differences were not significant. Stimulation

of female secondary sexual characteristics was observed in the devel-

opment of certain organs in both barrows and gilts.

Heitman and Clegg (1957) used 136 barrows and gilts in 4 experi-

ments and compared untreated pigs with pigs implanted with 30 or 60

mg of DES. Implanted pigs showed reduced gains, improved feed effi-

ciency, less backfat, and a greater percentage of lean primal cuts

than untreated pigs. The authors postulated that a possible protein

anabolic effect due to stilbestrol implantation could be causing the

increased carcass leanness.

Sewell, Warren, and O'Mary (1957) fed barrows and gilts averaging

18 kg initially to determine the effects of DES supplied orally at

levels 0, 1.1, 4.4, or 5.5 mg per kg of feed. They reported that gains

were not affected consistently in 3 different trials by DES supplemen-


Cahill et al. (1959) studied the influence of implanting stil-

bestrol on the carcass composition of boars, barrows, and gilts at

3 stages of maturity. They reported that stilbestrol implants of

1.5, 3.0, or 6.0 mg at 68 kg body weight had little effect on growth

rate or feed conversion ratio. They noted that a positive correlation

existed between level of DES implanted and both size of loin eye and

percentage of lean primal cuts.

Day et al. (1960) conducted a trial to determine the effects of

diethylstilbestrol and a combination of progesterone and estradiol on

growing-finishing swine. Poland China barrows were fed to market

weight on a practical diet. Treatments were administered by implant-

ing 6 mg of DES,.166.7 mg of progesterone plus 3.3 mg of estradiol

benzoate, or 500 mg of progesterone plus 10 mg of estradiol benzoate.

Differences in rate and efficiency of gain among the 4 treatment

groups were not statistically significant. Backfat thickness was

generally reduced by the hormone treatments, with both levels of the

progesterone-estradiol combination showing a significant effect.

Backfat probes for the 4 treatments averaged 3.91, 3.76, 3.56, and

3.45 cm respectively for the control, DES, low level progesterone-

estradiol, and high level progesterone-estradiol treatments. Carcasses

of pigs administered the high level of progesterone-estrogen treat-

ment had the lowest percentage of fat and highest yield of lean, evi-

denced by a significantly higher percentage of lean primal cuts,

larger loin eye area, and lower backfat thickness than other treatment


Beacom (1963) studied the effect of stilbestrol and estradiol-

testosterone implants on performance and carcass traits of market

swine fed different finishing diets. He reported no differences in

growth rate between control pigs and implanted pigs, but hormone

implants significantly decreased average daily feed intake. Carcass

parameters exhibited no significant differences bct;ccn control and

implanted pigs.

Gorrill, Bell, and Williams (1964) reported on an experiment

designed to measure the effects of DES implantation on the performance

of pigs on a restricted feeding regimen. Pigs weighing 50 kg ini-

tially were implanted with 12 mg of DES and finished to 91 kg. Im-

plantation with DES reduced barrow average daily gain from 0.69 kg

to 0.62 kg, but had no effect on gilt average daily gain. Feed intake

of barrows was reduced from 2.72 kg to 2.41 by DES, but gilt feed

intake was affected in the reverse manner, going from 2.27 kg to

2.45 kg. Implanted gilts digested protein better than did control

gilts, but the opposite was true for barrows. Loin eye area and back-

fat thickness were only slightly affected by DES, although the trend

was favorable in both cases.

Teague et al. (1964) conducted 7 trials to determine the effec-

tiveness of implanting boars with DES as a method for overcoming or

delaying the development of the odor or flavor commonly associated

with boar meat, and for retaining or further improving the favorable

performance and muscling characteristics of the boar. The feedlot

performance and carcass traits of market barrows, boars, and boars

implanted with 48 mg of DES at 70 kg or 96 mg of DES at 65, 70, or

75 kg were compared. Boars implanted with 96 mg of DES at 70 kg had

a significantly faster rate of gain than other groups. Feed conver-

sion was also favorably affected in this same group. The authors

found that carcasses of barrows were significantly shorter and fatter

than those of either boars or implanted boars. Sex odor and flavor

in the 10th rib chops were significantly reduced by implantation with

DES. In addition, no carcasses of boars implanted with DES were con-

demned for odor or flavor.

Plimpton (1966) implanted boars with 96 mg of DES at 70 kg and

fed them to 136 kg to determine the effects of the drug during extend-

ed growth on carcass composition, muscle quality, and palatability

of meat. Average daily gain and percentage of lean primal cuts were

significantly increased in implanted boars. Sex odor in meat of im-

planted boars was significantly reduced. No differences were observed

in marbling or color of the loin eye. Chemical evaluation of the loin

eye muscle showed no difference due to DES except percentage of mois-

ture and fat. Implanted pigs had significantly more moisture and

less fat in the lean of the longissimus dorsi muscle.

Plimpton et al. (1967) studied the performance, carcass traits,

and carcass composition of barrows, boars, and boars implanted with

96 mg of DES measured from live weight of 70.4 kg to 136.1 kg. Car-

cass measurements were related to treatment, age, time of slaughter,

and carcass weight. Implantation of boars with 96 mg of DES at 70.4

kg increased rate of gain and rate of lean primal cut deposition.

The rate of deposition of lean cuts was increased in implanted boars,

compared to control boars, for 10 of the 12 weeks following

implantation. This period also coincided with the time during which

DES significantly repressed sex odor in treated boars. All boars,

regardless of treatment, had carcasses significantly longer, leaner,

and with a higher yield of lean primal cuts than the carcasses of lit-

termate barrows of the same weight. A trend toward increased loin

eye area due to DES was observed. The yield of edible portion of

ham from boars was significantly more than that from barrows, and

the percentage of fat in the ham was also significantly lower for

boars. -Measures of growth such as loin eye area, carcass length, and

percentage of lean primal cuts were observed to increase in a linear

fashion with increasing age and weight. Differences in carcass com-

position were related to changes in weight.

Echternkamp et a]. (1969) studied the relationship between in-

tensity of boar odor and flavor and glandular development in normal

and DES implanted boars. They reported that implanting 96 mg of DES

at 70.3 kg significantly reduced the incidence of boar odor and flavor

to a live weight of 127 kg. In addition, DES significantly increased

average daily gain up to 104 kg and decreased the weight of accessory

sex glands. These authors also reported that there was a high corre-

lation between odor and flavor scores. They concluded that DES pre-

vented or delayed the development of boar odor and flavor.

Hale and Johnson (1970) fed ih4 weanling Duroc barrows individ-

ually to study the effects of season (summer vs. winter), energy con-

centration (high vs. low), and orally administered hormones (none,

diethylstilbestrol, or methyltestosterone), on performance in the

feedlot and on carcass characteristics of the pigs. The only

significant effect of feeding 2 mg of DES per day was a 2 percent

increase in the weight of the lean primal cuts.

The papers previously cited provide a general picture of the

effect of estrogens, notably diethylstilbestrol, on the performance

and carcass characteristics of swine. Although different workers have

observed conflicting results in some cases, an overall trend is appar-

ent. Treatment with DES generally reduces feed intake and improves

feed conversion. Growth is usually depressed in barrows and gilts,

but may be increased in boars. There seems to be a definite improve-

ment in carcass leanness in all sexes. DES has also shown ability

to suppress or delay the development of boar odor or flavor, at least

up to 100 kg of body weight. Benefits in feed efficiency and lean-

ness due to DES are not apparent in younger pigs, but in pigs from 45

kg to market weight, DES can be of some value in improving efficiency

and leanness.

The Effects of Androgens on the
Growth and Carcass Quality of Swine

Researchers have long known that males generally produce leaner,

more heavily muscled carcasses than do females or castrate males.

Literature previously cited documents sex differences in growth and

carcass quality in swine. Researchers have attempted to produce

this increased leanness and muscling in females and castrated males

by replacement therapy with testosterone since the early 1950's.

Woehling et al. (1951) implanted 30 mg of testosterone in 20 kg

barrows and gilts at the start of the experiment and again at 12 weeks.

They were unable to demonstrate a response in any performance or car-

cass parameter due to testosterone therapy.

Noland and Burris (1956) fed methyltestosterone (MT) at a level

of 0, 0.015, 0.15, or 1.5 rng per kg of body weight to boars, barrows,

gilts, and castrated gilts. They noted that the rate of body weight

gain of females was slightly depressed by 0.15 mg of MT per kg of body

weight, but gains of males were not affected. All sexes fed MT had

leaner carcasses, evidenced by a higher percentage yield of lean

primal cuts, compared to control pigs. The authors noted that boars

fed the highest level of MT exhibited markedly depressed spermatogene-

sis, and interstitial tissue development in all boars fed MT was

depressed. They concluded that the levels of MT fed were not effec-

tive in inducing any growth stimulus.

Bratzler et al. (1954) made carcass comparisons of boars, tes-

tosterone implanted barrows (193 mg of testosterone per pig), and

barrows castrated at 18, 45, 64, or 82 kg. Boars and 82 kg castrates

had a higher percent of lean in the rough loin, less backfat, longer

carcasses, and a higher live weight and lean primal cut yield.

Quality of boar pork was judged unacceptable in palatability tests

for odor and flavor, but no difference in palatibility of chops be-

tween control barrows and barrows implanted with testosterone pro-

pionate was observed.. In this trial no differences due to

testosterone or castration were observed in rate or gain or feed con-


Beeson et al. (1955) administered 20 mg of MT per pig per day

in a practical ration to barrows and gilts fed from 23 kg to market

weight. Growth rate and feed efficiency were unaffected, but car-

casses from testosterone fed pigs contained heavier lean cuts (ham,

loin, Boston butt, picnic shoulder) and lighter fat cuts (fat backs,

bellies, jowls) than carcasses from control pigs. The percentage yield

for lean primal cuts was 62.4 percent for testosterone fed pigs and

58.8 percent for control pigs. Chemical analysis of carcass composi-

tion showed 5 percent less fat and 5 percent more lean in testoster-

one fed pigs than in control pigs.

Perry et al. (1956) tested the effect of various levels of orally

administered MT (0 to 62 mg of M1T per pig per day) on the growth and

carcass composition of growing-finishing barrows and gilts fed from

23 kg to market weight. They reported that a daily intake of 27 mg

or more of MT resulted in a highly significant growth depression, but

also resulted in decreased fat deposition evidenced by decreased

backfat thickness.

Johnston, Zeller, and Hiner (1957) fed MT to swine at levels of

20 or 33 mg of MT per kg of feed. In 5 experiments they noted that

MT decreased rate of gain, average daily feed intake, backfat thick-

ness, and feed efficiency. There was no odor or flavor problem

reported in the meat of testosterone supplemented pigs. The authors

concluded that MT increased the ratio of lean to fat in the carcasses

of swine.

Whiteker et al. (1959) studied the effects of various androgens

at different levels on growth and carcass traits of pigs. They fed

96 barrows and gilts in 3 trials on practical diets containing either

methyltestosterone, methylandrostenediol, thyroprotein, or a combination

of the latter two. Rate of gain was not significantly affected by

any of these additives. Pigs fed the combination of methylandrostene-

diol and thyroprotein produced significantly leaner carcasses than

did those pigs fed either drug singly. Pigs fed MT produced carcasses

that had a significantly higher percentage of lean than did pigs fed

the basal ration. None of the treatments caused an adverse flavor

or odor in the meat. Loin protein content was not significantly

affected by any of the treatments. Masculine behavior and character-

istics were noted in the animals receiving MT.

Thrasher et al. (1959) conducted 3 experiments to determine the

effects of various testosterone analogs, combinations of testosterone

and stilbestrol, and late castration on the performance and carcass

quality of swine. No differences due to treatment were observed in

any parameter tested, although there was a trend toward increased

leanness in pigs fed MT singly or in combination with DES.

Baird and McCampbell (1959) reported no differences in feedlot

performance or carcass quality in pigs fed 0.55 mg of hydroxyzine per

kg of feed. Another test comparing androgenic compounds with DES,

estradiol-progesterone, and a basal ration failed to show any signifi-

cant differences due to any treatment. Other combinations of hormones

and tranquilizer substances were tested and they also failed to pro-

duce any changes in growth or carcasses of swine.

Cantwell, Johnston, and Tabler (1962) fed swine methyltestoster-

one and 17-ethyl-19-nortestosterone under various experimental con-

ditions to determine their effects on growth and carcass character-

istics, with special emphasis on glands and internal organs.

Methyltestosterone and 17-ethyl-19-nortestosterone fed at 20 to 33 mg

per kg of feed singly and in combination with stilbestrol at 13 mg

per kg of feed caused highly significant increases in weight of

liver, kidney, heart, and thymus gland. Average daily gain was

decreased significantly, as was adrenal gland weight. The authors

reported that methylstestosterone was more potent than 17-ethyl-19-


Mlente et al, (1962) studied the effect of 9-fluoro-ll-hydroxy-

17-methyltestosterone (Halotestin), a testosterone analog of great

potency. Barrows and gilts weighing 32 to 57 kg were fed 0 to 27.5

mg of Halotestin per kg of diet. They reported a significant decrease

in backfat thickness, and an increase in percent yield of lean primal

cuts due to Halotestin. Gains were depressed in pigs fed the hormone

compared to gains of those fed the basal diet.

Hale and Johnson (1970) fed weanling pigs methyltestosterone at

a level of 20 mg per day. They reported that MT decreased rate of

gain, daily feed intake, dressing percentage, and backfat thickness,

but increased carcass length, area of loin eye, and weight of the

4 lean cuts. They concluded that methyltestosterone had a potent

anabolic action in swine, evidenced by the increased leanness in car-

casses of pigs fed MT.

The previously cited papers present a review of the effects of

androgenic compounds on the growth and carcass characteristics of

swine. Of all androgens in use, methyltestosterone is probably one

of the most practical and anabolically potent. There seems to be

rather strong evidence that lIT is capable of inducing in swine

measurable carcass changes in a favorable direction. These papers

indicate that pigs fed methyltestosterone gain more efficiently, and

produce leaner, meatier carcasses than do pigs fed normal rations.

There is some evidence that high level testosterone therapy may pro-

duce significant odor or flavor problems in pork.

The Effects of Combinations of Androgens and Estrogens
on the Performance and Carcass Quality of Swine

Research has indicated that there is some benefit to be derived

from feeding or implanting estrogens or androgens in growing swine

of all sexes. Although changes in performance and carcass are not

always great or drastic, there is nevertheless a definite trend to-

ward decreased feed consumption and increased carcass leanness due

to hormone therapy. Since estrogen supplementation has shown partic-

ular usefulness with regard to boars, some workers feel that using

the combination of androgen and estrogen in barrows'and gilts would

prove more beneficial than either compound used singly. Work has

been done using combinations of estrogenic and androgenic drugs to

determine if the effects of the two substances used together are


Thrasher et al. (1959) studied combinations of testosterone and

stilbestrol and their effects on carcass quality and feedlot perfor-

mance in growing-finishing pigs. In 3 trials involving a total of 180

pigs they reported a non-significant trend toward increased carcass


Beacom (1963) implanted finishing pigs with a combination of

estradiol and testosterone. He observed no difference In growth

rate between controls and treated pigs, but there was a significant

decrease in average daily feed consumption caused by the estradiol-

testosterone implant combination. Beacom also reported an increase

in 'oin eye died in Lreated pigs fed a low energy diet. Other

indices of carcass leanness were favorably improved.

Wallace et al. (1967) conducted a 2 x 2 x 2 factorial experiment

involving protein level, sex, and supplementation with a combination

of DES and MT. The trial involved 48 pigs which averaged 59 kg

initially. The pigs were slaughtered as they reached 95 kg. Feedlot

performance and carcass characteristics were studied. Hormone supple-

mentation with DES + MT significantly decreased average daily gain,

average daily feed intake, and average backfat thickness. In addition,

there was a significant interaction between protein level and hormone

supplementation for average feed conversion ratio, which was inter-

preted as evidence that hormone supplementation favored improved feed

conversion in the presence of increased protein. Secondary sex glands

in barrows (Cowper's gland, prostate gland, and seminal vesicles) and

ovaries and uteri in gilts were markedly affected by hormone supple-

mentation. All these organs exhibited hypertrophy in hormone

supplemented pigs. Loin roasts were checked for any Indication of

boar odor or flavor. A strong influence on odor and flavor of pork

was exerted by DES + MT. The meat from some hormone fed pigs had a

very undesirable odor and flavor when cooked. Both gilts and barrows

were affected to the same degree. The authors concluded that the

odor was probably due to methyltestosterone.

Baker et al. (1967) fed 448 finishing pigs in 3 trials to eval-

uate the effects of a dietary combination of DES + MT. The effects

of sex and dietary protein level on hormone response were also

studied. Regardless of sex or protein level, carcass leanness was

improved by DES + MT. Improved feed efficiency due to hormone,

however, resulted only at higher levels of protein. These workers

also observed that feed efficiency and carcass leanness response to

DES + MT was greater in barrows than in gilts. Growth rate and feed

conversion efficiency were greatest at a dietary protein level of

12 percent in barrows and 14 percent in gilts, but for maximum carcass

leanness response, barrows needed 14 percent protein and gilts re-

quired 16 percent. Protein level did not appear to affect backfat

thickness in any of the trials, but the remainder of carcass lean-

ness parameters were improved additively by both DES + MT and increased

protein level.

Baker, Diller, and Jordan (1968) observed that DES + MT caused

a lowering of serum triglycerides level when fed to gilts. This de-

crease did not occur in barrows. Serum cholesterol and free fatty

acids were not affected by hormone treatment. The mechanism by which

DES + MT decreased serum triglycerides in gilts was not elucidated.

Doornenbal and Frankenham (1969) studied growth, feed conversion

ratio and chemical composition in market weight barrows and gilts fed

DES + MIT plus tylosin. They reported a trend toward increased gains,

improved feed efficiency and a reduction in age to market. Carcass

measurements within sex were not significantly different between

controls and hormone fed animals. There was a trend toward increased

leanness in barrows, but toward increased fat deposition in gilts.

The authors concluded that different proportions of sex steroid hor-

mones would be required for barrows and gilts to achieve equally

beneficial effects on carcass composition.

Heyer et al. (1968) evaluated the effects of a dietary combina-

tion of DS + I T onr the reproductive performance of gilts fed 2.2 Or

4.4 mg each of DES and MT per kg of diet during the finishing phase

only, or continuously through finishing to breeding. A total of 136

gilts was used in 5 experiments. These workers reported that feeding

the hormonal combination through breeding inhibited estrus. Some

gilts conceived after termination of hormone feeding. Gilts which

received the hormone only during the finishing phase had normal estrus

cycles and conception was reduced in only 1 of 3 experiments. In

4 out of 5 experiments, DES + MT reduced litter size. It was noted

that gilts fed the hormone supplement during finishing farrowed smaller

litters at the first two farrowings. Litter size increased to that

of the control group by the third parturition. The authors concluded

that inhibition of the normal reproductive function by DES + MT treat-

ment during the finishing period did not seem to be permanent. The

lower level of hormone addition was not as inhibiting to reproduction

as the high level.

Evidence accumulated by various researchers whose work was re-

viewed in the foregoing section indicates that there may be some addi-

tive performance and carcass improvement when estrogens and androgens

are fed or implanted in combination. The overall trend is much the

same as that observed when either type of drug is fed or implanted

alone. Combining the two substances seems to produce a more power-

ful stimulus to the metabolism of the animal, resulting in the changes

in feedlot performance and carcass composition reported. The entire

picture is unclear as yet regarding the mechanism of action of these po-

tent humoral substances. Also, observed responses to these drugs

are not always consistent in swine. It does appear, however, that '

there may be some benefit to be derived in feedlot performance in-

crease and in favorable changes in carcass characteristics by supple-

menting growing-finishing pigs with a combination of estrogen and


There do not appear to be any permanent adverse effects on

reproductive capacity of gilts fed DES + MT through the finishing


The Effects of Androgens on
Protein Anabolism in Animals

The influence of androgens on nitrogen retention has been known

since 1935 (Dorfman and Shipley, 1956) when it was discovered that

extracts of urine containing androgenic material stimulated nitrogen

retention in dogs.

Drill and Saunders (1956) used rats to test the ratio of anabolic

to androgen activity in a number of steroids. Of the testosterone

analogs tested, 17-ethyl-19-nortestosterone was found to be the most

potent anabolically and also to have the highest ratio of anabolic to

androgen activity. This compound was reported to be 5 times more

anabolically active than 17-a-methyltestosterone when administered

orally to rats, while the androgenic activity of methyltestosterone

was relatively high.

Leathem (1956), in a rat experiment, found that the state of

body protein stores at the time of hormone administration determined

in large part whether or not an anabolic response was observed.

Older rats and protein depleted rats exhibited a marked increase in

nitrogen retention when testosterone or other anabolic steroids were

administered. Very little response in young, healthy rats fed high

protein diets was observed. Leathem concluded that in many instances

nutrition appears to be dominant over anabolic hormones, even though

steroids are known to be involved in protein anabolic processes.

Applezweig (1962) reported on radioisotope studies In which rats

were fed 15N-labeled glycine with and without androgen therapy. An

increase in amount of 15N-labeled glycine retained was apparent for

the treated group. The author concluded that androgen influenced the

reaction of amino acids +-* proteins and caused the reaction to pro-

ceed in favor of protein synthesis. He postulated that either an

inhibition of protein catabolism or a stimulation of anabolism could

be the mechanism of action. In addition, Applezweig stated that when

body protein stores were filled, little or no anabolic response to

androgen treatment was observed.

Robinson and Singleton (1966) tested the effects of norbolethone,

an anabolic steroid, on the performance and body composition of

barrows. They used 24 Large White barrows fed two levels of protein

with and without 0.1 mg of steroid per kg of body weight. On the

low protein diet, steroid therapy increased growth, but the opposite

was true for the high protein diet. This interaction was significant.

In addition, there was a significant improvement in percentage of

lean in the carcass and loin eye area, but a decrease in carcass


Evidence presented in the papers previously cited indicates

that there is a definite protein anabolism in animals following

therapy with certain steroid hormones. Response varies according to

species, age, nutritional status, and sex of the animal. In general,

steroid anabolism is most marked in those animals in a state of

protein depletion.

The Effects of Diethylstilbestrol on
Protein Anabolism in Animals

Researchers have attempted to determine the mechanism of action

of diethylstilbestrol in stimulating growth. There is a general

agreement that increased nitrogen retention due to protein anabolism

occurs in ruminants consistently, and to a more variable degree in

monogastrics. The exact means by which DES causes this remain un-


Clegg (1952) reported on the use of DES to increase nitrogen re-

tention in steers. The nitrogen retention of steers implanted with

60 mg of DES was more than twice that shown by control animals.

Jordan and Bell (1952) studied nitrogen retention in lambs im-

planted with 12 mg of DES. Hormone implantation did not appear to

alter digestion of feed or nitrogen retention.

Whitehair, Gallup, and Bell (1953) implanted lambs with 24 mg

of DES to study the effects on calcium, phosphorus, and nitrogen

balance. There was no difference in the digestibility of feed be-

tween implanted and control lambs, but DES caused a significant In-:

crease in the amount of calcium, phosphorus, and nitrogen retained.

DES implanted lambs also showed faster rates of gain than control


Tillman and Brethour (1955) fed lambs 6 or 10 percent protein

with and without 3 mg of DES per day to study the effects on calcium,

phosphorus, and nitrogen metabolism. Nitrogen retention and average

daily gain were decreased by DES in the 6 percent protein ration,

but the reverse was true for the 10 percent protein ration. The

authors concluded that the effects of DES were not consistent.

Struempler and Burroughs (1955) studied the effects of growth

hormone and DES on nitrogen retention in lambs fed low or high energy

and low or high protein diets. Growth hormone or DES alone resulted

in increased nitrogen retention, regardless of dietary energy or pro-

tein level. When administered together, however, growth hormone and

DES did not produce an additive response. The authors concluded that

DES may cause an increase in secretion of growth hormone in the


Sell and Balloun (1961) studied nitrogen retention of growing

cockerels as influenced by DES or MT. DES resulted in decreased ni-

trogen retention, while MT did not significantly alter nitrogen


Carew and Hill (1967) studied the effect of DES on protein

utilization in chicks fed diets containing glucose or corn oil as

the major energy component. Nitrogen retention was markedly decreased

by DES in the high fat diet at restricted levels of energy intake,

but not on the glucose diet. The authors concluded that in chicks

the effect of DES on certain metabolic processes was influenced by

the form in which dietary energy was supplied.

Lassiter et al. (1956) studied the minimum protein intake for

pigs for maximum nitrogen retention. They also investigated the pre-

cision of 3, 5, and 7 day collection periods for estimating nitrogen

balance. With 23 kg pigs, nitrogen retention increased with increas-

ing protein levels up to 18 percent. With 68 kg pigs, protein levels

from 10 to 22 percent did appear to affect nitrogen balance, but the

difference was not significant. These workers also reported that

after a 10 day preliminary period, the 7 day collection period offered

only a slight advantage over the 3 day collection period with 23 kg

pigs and even less advantage with 68 kg pigs.

The anabolic effects of DES vary markedly with species, age,

sex, diet, and status of body protein stores, as shown by evidence

in work cited in this section.

The Mechanisms of Anabolic Action of
Androgens and Diethylstilbestrol

The means by which certain steroid hormones and diethylstilbes-

trol stimulate anabolism have been the subject of intense scrutiny

by researchers as long as the anabolic effect has been known. There

has been no clarification of the exact mechanism by which these sub-

stances stimulate protein anabolism.

Dorfman (1961), at a symposium on the mechanism of action of

steroids, proposed a working hypothesis for androgens which places

the mechanism of action of androgens at the level of regulation of

rate of biosynthesis of specific enzyme systems (protein synthesis).

The action of androgen is visualized as producing the necessary criti-

cal enzyme concentrations which result in growth of tissue. Androgen

may act as an inhibitor of catabolism or an inducer of anabolism in

this capacity.

Wilson (1962) studied protein synthesis in rat seminal vesicle

tissue as influenced by testosterone. Radioisotope 14C-labeled

amino acids were used to study protein biosynthesis rate in tissue

following testosterone administration. Protein synthesis was

doubled 12 hours after testosterone administration and reached a

maximum (5 to 6 fold) within 24 to 48 hours. There was evidence

that this enhancement of protein synthesis was independent of either

amino acid transport or synthesis, but was secondary to the accelera-

tion of a specific step in protein synthesis, the conversion of

soluble ribonucleic acid amino acid complexes to microsomal ribo-


Further work should serve to elucidate more clearly the exact

mechanisms involved in anabolic action of androgens.

Several theories concerning the mechanism of action of diethyl-

stilbestrol in stimulating nitrogen retention have been advanced by

various workers. The most promising hypothesis concerns the effect

of stilbestrol on growth hormone secretion. Struempler and Bur-

roughs (1955) reported that both DES and growth hormone increased

gains and nitrogen retention in lambs. When both substances were

administered together, however, no additive effect was observed.

This observation led them to conclude that DES may cause an increase

in secretion of growth hormone from the pituitary gland.

Davis, Garrigus, and Hinds (1970) studied the metabolic effects

of DES and growth hormone in lambs. They also observed very similar

responses to DES and growth hormone administration, and also concluded

that secretion of growth hormone might be increased by DES.

Generally, however, the mechanism of anabolic action of DES re-

mains unclear. Even less is known about this substance than is

known about anabolic steroids. It does appear that DES stimulates

nitrogen retention more markedly and more consistently in ruminants

than in nonruminants.

No direct evidence for an increase in secretion of growth hormone

caused by DES has been presented, although there are indications that

this may be the mechanism by which DES improves growth and nitrogen



General Objectives

These experiments were conducted to investigate the effects of

hormone supplementation (DES + MT at 2.2 mg each/kg of feed) and the

interrelationships with protein level (12 to 16%) and sex (barrow or

gilt) in swine. Treatment effects were measured by feedlot performance,

carcass parameters, and nitrogen balance studies.

General Experimental Methods


The experiments reported herein are on file in the Swine Nutri-

tion section of the Animal Science Department, Institute of Food and

Agricultural Science, University of Florida, Gainesville, Florida,

32601. Six trials were conducted between February 1967 and October

1969 and the series designated as Swine Experiment 178. Individual

trials were numbered as Experiments 178-A through F.


Animals used were Landrace x Duroc 2 way and (Landrace x Duroc)

x Hampshire 3 way cross-bred pigs. They were raised at the University

of Florida Swine Unit and were fed a typical practical fortified

corn-soybean meal ration from weaning to the time they were placed on

experiment. Sound management practices in raising the baby pigs were

followed to ensure healthy experimental animals. Male pigs were cas-

trated at approximately 7 to 10 days of age. All pigs had their ears

notched at birth for identification and were vaccinated against swine

erysipelas at approximately 6 weeks of age. The pigs in the first

two experiments (178-A and B) were vaccinated against hog cholera as


Allotment, Feeding, and Weighing

Outcome groups were chosen on the basis of sex, weight, and

litter, and these groups were randomly assigned to treatments.

Pigs in all feeding trials were fed ad libitum from self

feeders. Pigs in the metabolism trials were full-hand-fed twice

daily. Water was supplied ad libitum from automatic water fountains.

All pigs were fed in confinement on concrete or steel mesh floors.

All feed used was in a dry meal form. Hormone feeding was discontinued

for 72 hours prior to slaughter. Feed was weighed back every 2 or 4

weeks and a final weighback was taken at the termination of the feed-

ing trial. Compositions of the diets, level of hormone supplementation,

and compositions of the mineral and vitamin premixes are shown in

Tables I through 5.

Animals were weighed initially, and at I or 2 week intervals

thereafter until slaughter. A platform scale was used for weighing.

Slaughter Procedure and Carcass Evaluation

As live weight of the pigs reached 100 kg, they were slaughtered

at the University of Florida Meats Laboratory. Carcasses were dressed

packer style (head off) for study. All carcass weights and measure-

ments were taken after the carcasses had been chilled for 48 hours at

2 50 C. The length of carcass was measured from the anterior edge

of the aitch bone (pelvis) to the anterior edge of the first rib.

Average backfat thickness was calculated from measurements taken at

the first rib, last rib, and last lumbar vertebra. Loin eye area

was determined as an average of the left and right sides. The loins

were cut perpendicular to the vertebral column between the 10th and

Ilth rib to expose the longissimus dorsi. Tracings of the perimeter

of the loin eye were made, and their area determined by the use of

a compensating polar planimeter. The carcasses were broken down by

standard procedure and weight of wholesale cuts was determined. In

addition, the loin eye muscle was scored for marbling, color, and

firmness (Tables 6, 7, and 8). Blade loin roasts and loin chops were

wrapped for freezing and were frozen and stored at -15* C. Before

cooking, roasts and chops were thawed overnight at 10 C. Roasts were

cooked in covered Pyrex dishes in an oven preheated to 175 C. The

same cooking temperature was used for chops as for roasts. Chops were

cooked in Pyrex Petri dishes covered with watch glasses. Roasts were

cooked 60 to 80 minutes per kg to an internal temperature of 175* C;

chops were cooked for approximately 30 minutes. Aroma and flavor were

determined by a trained 6 member panel. Degree of boar odor and flavor

were the only palatibility factors considered. Table 9 shows the code

used for scoring samples.

Tissue Sampling and Preparation

Loin chops 2.5 cm thick taken between the 10th and 13 rib were

wrapped for freezing and frozen and stored at -15' C for subsequent

chemical analysis. To prepare the sample chop for analysis, a band

saw was used to isolate the longissimus dorsi while the chop was still

frozen. All external fat and bone were removed. The remaining frozen

longissimus dorsi section was quartered with the band saw, placed in

a coded plastic bag, and returned to the freezer for pulverizing.

Longissimus dorsi sections were pulverized in the freezer room at

-15* C by placing each sample individually in a commercial duty, rotary-

blade blender with a I liter stainless steel container, along with

200 g of dry ice (approximately twice the sample volume). The blender

was cooled to -150 C in the freezer prior to use. The cover was placed

on the blender, held in place firmly by hand, and the blender was

switched on to high speed. After approximately 60 seconds the blender

was switched off, the pulverized, frozen composite of meat and dry

ice was placed in a coded plastic bag, and the bag was closed loosely

with a rubber band.

The pulverized samples were stored in the freezer at -15' C for

at least 24 hours prior to weighing out aliquots for analysis. This

storage interval was necessary to allow time for all of the pulverized

dry ice to sublime, leaving only the pulverized frozen meat in the

sample bag. Sample aliquots of powdered meat were weighed while frozen

in a cool room (2' 4 C) as quickly as possible to prevent thawing.

Feed Sampling and Preparation

Feed samples were taken from each mixing batch and pooled at the

end of the feeding trial. A sample of this composite was retained

for chemical analysis. Following drying, the sample of feed was ground

in a Wiley mill with a 1 mm screen. The ground sample was stored in

a coded glass screw-top bottle for chemical analysis.

Feces Sampling and Preparation

In the metabolism trials (Experiments 178-E and F) total collection

of feces from each pig for each 24 hours of the 6 day collection period

was performed. The feces were put in coded plastic bags, weighed to

the nearest 0.1 g on a single pan balance, frozen, and stored at -15* C

for later analysis. Preparation for analysis was begun by thawing the

frozen feces. The entire amount of feces from each pig for each day

of the collection period was placed individually in a commercial duty

rotary-blade blender with a stainless steel container having a 4 liter

capacity. An amount of distilled water equal in weight to the original

weight of the feces sample was added, and the blender was switched on

to high speed. The resulting slurry was a completely homogeneous mix-

ture from which a truly representative sample aliquot could be taken

easily. Following drying, each sample was ground in a Wiley mill

with a 1 in screen and stored in a coded glass screw-cap bottle.

Urine Sampling and Preparation

In the metabolism trials (Experiments 178-E and F), total collec-

tion of urine from each pig for each 24 hours of the 6 day collection

period was performed. The total volume of the daily urinary output

was measured to the nearest 5 ml in a 2 liter graduated cylinder.

From the total daily urinary output of each pig, an aliquot of approx-

imately 250 ml was filtered through cheesecloth into a coded poly-

ethylene screw cap bottle to which 1.0 ml of concentrated hydrochloric

acid was added as a preservative. The pH was tested with pHydrion

paper to be sure it was in the range of 1.5 to 2.0. If it was not,

concentrated hydrochloric acid was further added, drop by drop, until

the desired pH was obtained. Samples were then frozen and stored

at -15* C.

Analytical Methods

Weighing Samples

All samples for analysis were weighed on a single pan analytical

balance to 4 decimal places. Aluminum foil weighing dishes were used

for all samples except those on which nitrogen was to be determined;

those samples were weighed on small squares of glassine paper and

folded quantitatively within the paper for analysis.

Moisture Cetermination

Moisture was determined on all feed, feces, and meat samples

taken during the course of the investigation. Feed and feces samples

were dried prior to grinding as previously described and the moisture

was determined at this initial drying. The general procedure for

determination of moisture was similar for feed, feces, and meat.

Duplicate samples of the material being analyzed were quantitatively

weighed into numbered aluminum foil weighing dishes of known weight

and placed in a 1000 C drying oven. Feed samples were dried for 24

hours, but feces and meat samples required 48 to 72 hours before

a complete removal of water was accomplished.

The dried samples were cooled to room temperature in desiccators

and weighed to determine the loss of moisture. In the case of feces

samples it was necessary to correct for the water added during homo-

genization. Sample size for feed was approximately 50 g. Between

100 and 200 g of feces slurry was used for the moisture determination

on the feces samples. Meat sample size was between 5 and 15 g.'. Dried

samples of feed and feces were ground and stored as previously de- -

scribed. Meat samples remained in their small (6 x 1.5 cm) aluminum

foil weighing dishes and were stored in desiccators for later analysis.

Ether Extract Determination

The ether extract determination was performed on the same meat

samples used in the moisture determination. The small foil pans con-

taining the dried meat samples were carefully rolled up to quantita-

tively enclose the samples; then the rolled pans with samples were

placed in numbered Whatman cellulose extraction thimbles (25 x 80 mm).

The weight of each thimble, pan, and sample was quantitatively deter-

mined. Samples were then extracted for 24 hours with petroleum ether

on a Goldfisch apparatus. Following extraction, the samples were

dried and the weight of the thimble, pan, and extracted sample was

quantitatively determined. The difference was reported as fat.

Nitrogen Determination

A modified Kjeldahl process (W.V. Stradtmann, personal communi-

cation) was used for nitrogen determination. Feed, feces, and meat

samples for this determination were quantitatively weighed onto small

squares of glassine paper (approximately 8 x 10 cm).

The papers were then carefully folded to quantitatively enclose

the samples, and the papers with samples were put into coded 100 m!

Pyrex semi-micro digestion flasks. Sample size was approximately

0.4 g for feed and feces and 1.0 to 1.5 g for meat samples. Urine

samples were pipetted into the digestion flasks. Sample volume for

urine was 4.0 or 5.0 ml. After the sample was in the digestion flask,

5 or 6 glass beads were added to prevent bumping during digestion.

Concentrated sulfuric acid (5 ml) was used to char the samples for


The flasks containing samples, beads, and acid were then boiled

over a free flame until sulfur trioxide fumes appeared in the necks

of the flasks, and acid was refluxing down the necks and sides of the

flasks. The flasks were then removed from heat and allowed to cool

in the air for about 1 minute. Superoxol (30% hydrogen peroxide) was

added drop by drop to the hot acid digests until the blackish-brown

mixture turned clear, indicating complete oxidation of organic matter.

The digested sample was then cooled in the air to ambient temperature

and quantitatively transferred from the semi-micro digestion flasks

to 500 ml macro distillation flasks. Three washes with distilled water

were used to accomplish the transfer. The sample was then treated as

in the normal Kjeldahl process (A.O.A.C., 1960). Mossy zinc and

concentrated sodium hydroxide were added and the alkaline mixture

was distilled to drive off ammonia into receiving flasks containing

50.00 ml of dilute sulfuric acid of known normality. Following dis-

tillation, the acid remaining in the receiving flasks was titrated

to the methyl red end point with 0.1000 normal sodium hydroxide.

The percent nitrogen in the samples was then calculated, and in the

case of feed samples and meat samples it was multiplied by a factor

of 6.25 to convert to percent protein. A blank and a standard

(ammonium sulfate) determination were run with every group of 24


Determination of 17-ketosteroids in Urine

A determination of the urinary 17-ketosteroids (Sigma Tentative

Technical Bulletin No. 17-KS) was performed on composite samples of

urine from each pig in the metabolism trials (Experiments 178-E and

F). In order to compensate for variation in daily urine output vol-

ume, samples from each pig for each day of the collection period were

pooled in a ratio comparable to the daily urine volume. Duplicate

determinations of 17-ketosteroids were run on the composite samples

and the results were reported as average excretion of 17-ketosteroids

in mg per day. The Zimmerman reaction (Dorfman and Shipley, 1956)

was used to determine concentration of 17-ketosteroids in urine. Fil-

tered urine samples of 5.0 ml were acid hydrolyzed (to free conjugated

steroids) in a boiling water bath for 15 minutes, cooled, and trans-

ferred to separatory funnels. The hydrolyzed samples were then

extracted with approximately 20 ml of ethyl ether and washed with

2.0 normal sodium hydroxide. The washed extracts were filtered into

large test tubes, evaporated to dryness, and redissolved in 0.20 ml of

absolute methanol. The alcoholic solutions were incubated at room

temperature for 20 minutes following the addition of 0.20 ml of

meta-dinitro-benzene and 0.20 ml of 8.0 normal potassium hydroxide

to each sample. Following incubation, 1.0 ml of distilled water and

5.0 ml of methylene chloride were added to each sample and the solu-

tions were shaken to mix thoroughly. Approximately 5 minutes after

shaking, the top aqueous layer was aspirated off the solutions and

1.50 ml of absolute methanol was added to allow development of the

purplish color characteristic of the steroid-dinitrobenzene complex.

Solutions were transferred to cuvettes and the percent transmittance

was read in a colorimeter with the blank solution as a reference for

100 percent transmittance. Maximum absorbency occurred at a wavelength

of 540 mu.

A standard solution was also carried through the extraction pro-

cess with every 8 determinations. The percent transmittance values

of a series of solutions of known concentration were plotted on semi-

logarithmic graph paper to produce a linear standard curve from which

the concentration of 17-ketosteroids in unknown solutions could be

determined directly. The concentration of 17-ketosteroids in mg per

liter was multiplied by the mean daily urine output in liters to give

the value in mg of 17-ketosteroids excreted per day.

Statistical Methods

All data collected from the experiments were analyzed statis-

tically using the methods of Steel and Torrie (1960). Analysis

of variance was used to determine significant effects. Wherever

significant main effects were not complicated by interaction, pooled

means for the main effects are presented in the figures. Any refer-

ence to statistical significance regarding main effects refers to

the probability level of 5 percent or less.

Wherever significant 3 factor interaction occurred, means for

the treatments were tested for significant differences by Tukey's w

procedure using the upper 10 percentage points of the studentized

range. Wherever a significant 2 factor interaction occurred in the

3 factor experiments (178-A and B) data were summed and averaged

across the independent factor. The 2 factor simple effects were then

tested for significant difference by Tukey's w procedure using the

upper 10 percentage points of the studentized range. Treatment means

in the 2 factor experiment (178-D) were tested in a similar manner

where interaction occurred.

Since Tukey's procedure is so conservative, Steel and Torrie

(1960) suggest that the experiment-wise error rate can be relaxed to

10 percent without danger of committing a large number of Type I

errors (declaring observed differences falsely significant). Because

of this, the 10 percent level was used to test for significant differ-

ences in these experiments where interaction occurred.

The standard deviation of a treatment mean (s-) was estimated by

/error mean square
/ no. of observations in mean for calculating w. The value of

S= qp,n2 s, where a = 0.10, p = number of means being compared,

and n2 = error degrees of freedom. The q values were obtained from

tables of the upper percentage points of the studentized range

(Beyer, 1966).

Experiment 178-A


A group of 72 carefully selected crossbred pigs was placed on

experiment at an initial average weight of 45 kg. This first trial

was begun on February 16, 1967. Pigs were group fed in concrete con-

finement from a self feeder to an average weight of 95.3 kg, at

which time the entire group was slaughtered for carcass study. The

termination of the feeding trial was on April 22, 1967, 66 days after

the starting date. The design of the experiment was a 2 x 2 x 2

factorial design (Table 10) which involved sex (barrow and gilt),

protein level (16 and 12% protein), and hormone supplementation

(basal and DES + MT, each at 2.2 mg/kg of feed). Compositions of

the rations used are shown in Table 1.


The summaries, analysis of variance plans, and observed mean

squares for Experiment 178-A are presented in Tables 11 through 16

and Figures 1 through 12. Table 13 presents an overall summary of

all the responses measured in Experiment 178-A. Significant mean

squares are presented in Tables 14 through 16. Figures illustrate

all significant interactions and main effects.

Table 11 presents a summary of the feedlot performance of the

4 treatment groups. Table 12 shows the combined protein and hormone

treatment means and the appropriate standard deviations of treatment

means. The t test did not reveal any significant differcnccs in feed-

lot performance due to hormone or sex. Treatment means of total

gain from initial to market are shown in Table 13. There were no

significant differences in total gain between any treatments.

Carcass responses are shown'in Table 13. There was a signi-

ficant protein x hormone x sex interaction which affected dressing

percentage. This interaction is illustrated in Figure 1. Gilts

showed an increased dressing percentage on the basal ration as protein

was increased, and a decreased dressing percentage was noted when

protein was increased on the hormone supplemented ration. The reverse

effect was seen in barrows. Hormone increased dressing percentage

with increasing protein. Increasing protein on the basal ration did

not affect barrow dressing percentage. The effect of hormone supple-

mentation in reducing dressing percentage was significant only at

the 16 percent protein level in gilts and at the 12 percent protein

level in barrows. Due to this interaction, no inferences can be made

about the main effects on dressing percent.

There were two significant interactions which influenced percent

lean primal cut yield. The 2 factor hormone x sex interaction was

disregarded since there was also a significant 3 factor interaction.

The 3 factor protein x hormone x sex interaction illustrated in

Figure 2 shows that gilts responded nearly the same on the basal and

hormone rations to increased protein. There was an increased lean pri-

mal cut yield in gilts fed either diet (basal or DES + MT) when protein

was increased. Barrows showed increased lean primal cut yield in

response to hormone supplementation at both protein levels. Barrows

fed the 16 percent dict had a higher lean cut yield Lian those fed

the 12 percent protein regardless of hormone level. None of these

differences were significant (Table 13).

Percent ham was not affected by any factor except sex (Figure 3).

Gilts had significantly larger hams than barrows.

Percent loin was influenced by a significant 2 factor interaction.

This hormone x sex interaction is shown in Figure 4. Percent loin was

slightly decreased in gilts by hormone, but barrows showed a signifi-

cant increase in yield of loin in response to DES + MT. In addition,

gilts fed the basal diet yielded significantly higher percentages of

loin than basal barrows.

Percent yield of picnic shoulder was influenced by both hormone

and protein. There was a significant increase in percent picnic

shoulder in response to increased protein (Figure 5) and to hormone

supplementation (Figure 6).

Percent Boston butt was significantly increased by hormone

supplementation.(Figure 7). In addition, there was a significant

protein x sex interaction influence on yield of Boston butt. Barrows

showed a slight decrease in yield of Boston butt with increased pro-

tein, but gilts showed a moderate increase. Although this inter-

action was significant, none of the differences between means were

significant (Figure 8).

Backfat thickness was decreased significantly by both increasing

protein and DES + MT (Figures 9 and 10). No interactions were

observed to influence backfat thickness in this trial.

Loin eye area was not significantly affected by any of the treat-

ments in this experiment.

No significant differences in carccss length due to trcatmIICnt

were observed.

Loin eye marbling score was significantly reduced by increased

protein (Figure 11).

No differences due to treatment were observed in loin eye color

score or firmness score.

Loin roast aroma and flavor scores for boar odor incidence were

significantly increased by DES + MT in this trial. A graphic presen-

tation of this difference is shown in Figure 12.

Experiment 178-B


Experiment 178-8 was the second trial performed in the series,

and was designed in 2 parts. The first phase consisted of a completely

random design (Table 17) with sex of the pigs (barrow or gilt) as

the treatment factor. A carefully chosen group of 60 young crossbred

pigs with each sex represented equally was placed on experiment on

May 15, 1967. The average initial weight was 9.8 kg. The pigs were

segregated by sex and group fed on a 16 percent protein ration in

confinement on concrete to an average weight of 56.3 kg. The first

phase ended on July 25, 1967. The feedlot performance data collected

were analyzed to determine if there was any performance difference

In early life due to sex.

The second phase of the experiment was a 9 x 2 Y 2 factorial

design similar to Experiment 178-A. This trial was designed to further

investigate the effects of sex, protein level and hormone supplemen-

tation on growing-finishing pigs. The design of the experiment is

shown in Table 18. In this experiment it was decided to use a lower

level of protein (14%) than the 16 percent ration used in the first

trial, to see if a response to protein still occurred, and to see if

response to hormone remained the same at the lower level of protein.

Pigs in this trial were individually fed from self feeders in concrete

confinement pens. Compositions of the diets used are shown in Table

i. The 48 pigs used in this second phase were selected from the 60

pigs used in the first phase on a sex, weight, and littermate basis.

Starting date for the factorial trial was July 25, 1967. All pigs

were slaughtered (for carcass study) on an individual basis as ter-

minal weight reached approximately 100 kg.


The summaries of treatment means and analysis of variance plans

for Experiment 178-8 are shown in Tables 19 through 24 and Figures

1l through 22.

A summ-nary of the feedlot performance during the growing phase is

shown in Table 19. No significant differences were observed in per-

formance during early life between barrows and gilts fed a similar

16 percent protein ration (Table 20).

Average daily gain was significantly greater for barrows than

for gilts during the finishing phase (Figure 13). There was a signi-

ficant interaction of sex with DES + MT which influenced feed intake.

Barrows fed DES + MT ate significantly less feed during the finishing

phase than did barrows consuming the basal ration. Hormone supplemen-

tation did not affect feed intake in gilts (Figure 14). In addition,

Figure 14 shows that barrows fed the basal ration ate significantly

more feed than gilts fed either the basal or the hormone diet. Feed

efficiency was significantly improved by DES + MT in this trial

(Figure 15).

None of the main effects had a significant influence on dressing

percentage in this experiment, but there was a significant protein x

sex interaction effect (Figure 16). Increased protein resulted in

increased dressing percentage in barrows; this response was signifi-

cant in gilts.

There was a favorable effect of DES + MT on percent yield of lean

primal cuts. There was a significant interaction of sex x hormone

which is shown in Figure 17. This interaction manifested itself in a

differential response to hormone supplementation by sex. Gilts showed

only a slight increase in percent lean primal cuts, while barrows

showed a significant increase.

There were no significant differences observed In percent ham

In this trial.

There was a significant interaction of hormone x sex affecting

percent loin. Loin yield in gilts was not materially affected by

DES + MT, but barrows showed a significant increase in this cut due

to hormone supplementation (Figure 18).

Picnic shoulder and Boston butt percentage yield were unaffected

in this trial by any treatment.

Backfat thickness was significantly reduced in barrows by DES + MT

in this experiment. There were 2 significant interactions influencing

backfat thickness. The effects of both protein x hormone and hormone x

sex interactions are presented in Figure 19. The protein x hormone

interaction shows that average backfat thickness was not materially

affected by DES + MT on the high protein diet, but was significantly

reduced on the low protein diet. The hormone x sex interaction shows

that backfat thickness was not reduced in gilts fed DES + MT, but

was decreased to a significant extent in barrows.

Hormone x sex interaction significantly influenced loin eye area

in this experiment, but none of the treatment means differed signifi-


Carcass length was significantly increased by DES + MT in gilts

fed 12 percent protein in this trial. There was a significant 3 factor

interaction which influenced carcass length (Figure 20). Gilts fed

the basal ration showed an increase in carcass length as protein was

increased from 12 to 14 percent, but gilts fed the ration containing

DES + MT showed decreased length with increased protein. Thereverse

effect was true for barrows. DES + MT increased length of barrows

with increasing protein; barrows fed the basal ration showed a decreased

length as protein was increased. None of these effects were signi-

ficant, with the exception of the difference between gilts on the

basal and hormone rations at the 12 percent protein level.

Loin eye marbling score was not affected by any treatment in

this trial.

Loin eye color score was not signnficant!y different between any

of the treatment groups in this trial.

Loin eye firmness score was significantly affected by sex. Gilts

had significantly firmer muscle (10th rib 1. dorsi) than barrows

(Figure 21).

Loin roast aroma and flavor scores for incidence of boar odor

and flavor were significantly increased by DES + MT in this experi-

ment (Figure 22).

Experiment 178-C


The third trial in the series was designated as Experiment 178-C.

This trial was designed to examine the effects of DES + MT alone,

without protein or sex considerations. The experiment was a completely

random design (Table 25) utilizing 24 barrows individually fed in

concrete confinement from self feeders. The ration used (Table 1)

was a 14 percent protein corn-soybean meal diet fed with and without

2.2 mg of DES + MT per kg of feed. Pigs for this experiment were

randomly assigned to treatment from a uniform group. The trial com-

menced on January 23, 1969. Pigs averaged 45 kg initially and were

slaughtered on an individual basis for carcass study as weight reached

100 kg. There were 2 pigs in the trial, one assigned to each treat-

ment, with identical ear notch numbers; the identity of these two

animals was lost at slaughter. Therefore, the carcass data are all

based on the remaining 11 pigs in each treatment group.

Long ssimus dorsi samples from the 10th to 13th rib area were

analyzed for moisture, fat, and protein content in this trial.


The treatment means for Experiment 178-C are summarized in Table

26. Analysis of variance tables for this experiment are given in

Tables 27 through 31.

Out of 22 responses measured in this trial, only 3 showed any

significant differences.

Feedlot performance did not differ significantly between treat-

ments, but there was a trend toward decreased feed intake and improved

efficiency due to DES + MT.

None of the carcass objective measurements differed significantly

in this experiment, although there was a trend toward increased lean-

ness due to DES + MT. This was evidenced by slight increases in

carcass length and yield of lean cuts, and slight decreases in dressing

percent, backfat thickness and loin eye marbling score. Of all the

carcass leanness parameters, backfat thickness was most affected by

hormone supplementation, but even so, the difference was not signifi-


In this trial the only carcass subjective measurement which was

significantly affected by DES + MT was pork chop aroma score. There

was a significantly higher incidence of boar odor in chops from pigs

treated with DES + MT. None of the other carcass subjective measure-

ments, including chop flavor score, roast aroma score, and roast

flavor score, were significantly different.

Analysis of longissimus dorsi samples revealed a significantly

luwer percenLdge uo dry matter (higher % moisture) in pigs fed DES +


The percent protein in longissimus dorsi was significantly greater

for pigs fed DES + MT. Protein was expressed on a dry matter basis.

There was no significant difference in percent fat in longissimus

dorsi, although there was a trend toward decreased fat due to DES +


Experiment 178-D


Experiment 178-D was the last in a series of 4 feeding trials.

In this trial, the design was a 2 x 2 factorial (Table 32) involving

sex and hormone supplementation. The protein level was fixed at

14 percent of the diet (Table 1). The crossbred pigs used in this

experiment were selected from outcome groups based on sex, weight,

and littermate, and were randomly assigned to treatments. The pigs

were fed in individual concrete confinement pens from self-feeders.

The average initial weight was 54.5 kg. Pigs were slaughtered on an

Individual basis for carcass study as they reached 100 kg. The trial

commenced on May 19, 1969. On this trial, one barrow died midway

through the experiment. Death was attributed to generalized edema

due to heat prostration. One pig carcass was condemned for a condition

of granuloma in the muscle, apparently unrelated to treatment. Be-

cause the orthogonality of the factorial design was destroyed by loss

of these data, computer analysis using a complete and a reduced model

was necessary in order to partition the sums of squares. Therefore,

only abbreviated analysis of variance tables are shown, and sums of

squares generated from these tables are not additive.


The summary of treatment means is shown in Table 33, and abbre-

viated analysis of variance tables are presented in Tables 34 through

37 and Figures 23 through 38 illustrate significant effects.

The interaction of hormone and sex influenced daily gain signi-

ficantly. This interaction is graphed in Figure 23, which shows

that daily gain in gilts was not materially affected by DES + MT,

but was significantly reduced in barrows by the hormone. Barrows fed

the basal diet gained significantly more than did gilts fed the basal


Average daily feed intake was significantly greater in barrows

than in gilts (Figure 24). Hormone supplementation also influenced

daily feed intake significantly. Pigs fed DES + MT consumed signifi-

cantly less feed than those fed the basal diet (Figure 25).

Feed conversion efficiency was favorably affected by DES + MT.

Pigs consuming the hormone supplemented feed had a significantly

lower feed conversion ratio than pigs fed the basal diet. This differ-

ence is shown in Figure 26.

Dressing percentage was not affected by any treatment in this


Hormone supplementation markedly increased the percent yield

of lean primal cuts in this experiment (Figure 27).

There were no significant main effects seen in percent ham yield,

but the hormone x sex interaction was significant. This interaction

is illustrated in Figure 28. The graph shows that DES + MT decreased

yield of ham slightly in gilts, but increased it significantly in

barrows. Gilts fed the basal ration had significantly larger hams

than barrows fed the basal ration.

Percent yield of loin was not significantly affected by any


Percent yield of picnic shoulder was increased by DES + MT. This

effect was significant (Figure 29).

There was also a positive significant response to DES + MT

manifested in percent yield of Boston butt (Figure 30).

Backfat thickness was significantly reduced by supplementation

with DES + MT (Figure 31).

Loin eye area was not affected by any treatment in this trial,

nor was carcass length. Liver weight was also measured in this trial,

but no significant differences due to any treatment were observed.

Loin eye marbling score, loin eye color score, and loin eye firmness

score were all unaffected by any treatment.

Loin tenderness score was significantly different between sexes

(Figure 32). The meat from barrows required less shear force to part

the fibers than did that from gilts.

In this trial, the boar odor and flavor incidence scores for

pork chop aroma and flavor and loin roast aroma and flavor were sig-

nificantly increased by DES + MT (Figures 33 and 34).

Moisture, fat, and protein were determined on longissimus dorsi

samples taken from the 10th to 13th rib area. The percent dry matter

i. the melt '.s not significantly different bet...'cen

Percent protein in longissimus dorsi (expressed on a dry matter

basis) was significantly lower in barrows than in gilts, and was

significantly decreased by hormone supplementation (Figures 35 and 36).

Percent fat in longissimus dorsi (expressed on a dry matter

basis) was significantly affected by sex and DES + MT. In this trial,

gilts showed significantly less fat in the lean tissue than barrows

(Figure 37). Supplementation with DES + MT significantly increased

the percent fat in longissimus dorsi over that found in pigs fed the

basal ration (Figure 38).

This trial concluded the series of feedlot performance and

carcass study experiments. Table 44 presents a summary of all the

significant performance and carcass responses observed in the 4 trials.

Experiments 178-E and F


Experiments 178-E and F were the last two experiments performed

in the 178 series. Both of these trials were metabolism studies.

Barrows were housed in metabolism crates constructed so as to permit

total collection of all excreta separately. The crates were equipped

with automatic water fountains, and with fans for cooling. The floors

were of expanded steel mesh. Barrows were full-hand-fed twice daily

and a record of daily feed intake was made. Barrows were weighed,

placed in the crates, and fed the experimental diets for a period

of acclimatization to the regime. The pretrial period was 9 days in

the first metabolism trial and !! days in the second one. Collection

of total feces and urine excreted was made as previously described

for a period of 6 days in both trials. Barrows were weighed again

at the termination of the feeding period.

The design of the experiments is shown in Table 38. In the

first metabolism trial (conducted from May 29 to June 12, 1969),

crossbred barrows averaging 58 kg initially were used; terminal

average weight was 65.7 kg. In the second metabolism trial (conducted

from July 28 to August 14, 1969), similar barrows were used. Average

initial weight was 57.1 kg, and average terminal weight was 67.8 kg.

Each trial consisted of 8 barrows; the blocks used in the design

were littermate pairs, and four barrows were assigned to each treat-

ment. The basal (14% protein) diet was fed with and without 2.2 mg

of DES + MT per kg of feed, as shown in Table 1.

Criteria examined in both trials were daily feed intake, total

gain, daily nitrogen retention (g N/kg feed consumed), apparent di-

gestibility of dry matter and nitrogen, and excretion of 17-keto-

steroids in urine.


The treatment means for both trials are shown in Table 39, and

analysis of variance plans are presented in Tables 40 and 41 for

for Experiment 178-E and Tables 42 and 43 for Experiment 178-F.

No significant difference due to DES + MT was observed in daily

feed intake, although a slight decrease in feed intake in the first

metabolism trial and a more marked decrease in the second occurred

in pigs fed the hormone supplement.

Total gain was veiy slighLiy deuresede in pigs Fed DES + MT in

Experiment 178-E, but was moderately increased in hormone supple-

mented pigs in Experiment 178-F. Neither difference was significant,


Daily nitrogen retention, expressed as g of nitrogen retained

per kg of feed consumed, did not differ significantly due to treat-

ment in either trial. Pigs fed DES + MT showed a moderate decrease

in nitrogen retention in the first metabolism trial, but showed only

a slight decrease in the second trial; neither difference was great

enough to be significant.

Apparent digestibility of dry matter and nitrogen was similar

for both treatment groups in both trials. Digestibility did not appear

to vary between trials, either.

In the first metabolism trial, excretion of 17-ketosteroids in

urine was significantly different due to treatment. Pigs fed DES +

MT had a higher daily excretion of 17-ketosteroids in urine than pigs

fed the basal ration. In the second trial opposite results were ob-

served. Pigs fed the hormone supplement in this experiment showed a

lower daily excretion of 17-ketosteroids in urine than did pigs fed

the basal diet, but this difference was not significant.


The Effects of Hormone, Protein, and Sex on the
Fprdlot Pprfnrminrp nf Grrwin n-Finiching Swin"

Several recent studies have been reported which indicate that

OES + MT affects the performance of swine in the feedlot.

Wallace et a!. (1967) reported a significant decrease in both

average daily gain and average daily feed intake due to feeding DES +

MT at 2.2 my each per kg of diet.

Baker et al. (1967) reported that DES + MT decreased average

daily gain in barrows, but not in gilts. They observed also that feed

efficiency response to DES + MT was obtained only at higher levels

of protein.

Doornenbal and Frankenham (1969) reported a non-significant

increase in average daily gain for gilts and barrows fed a practical

high protein ration containing 2.2 mg each of DES + MT per kg of feed,

but they reported that feed efficiency was not altered by treatment.

Average Daily Gain

In this series of experiments, rate of gain was affected signif-

icantly by hormone in only 1 out of 4 trials (Table 44). Hormone

treatment decreased rate of gain only in barrows in this particular

case, since there was a significant interaction of hormone x sex.

Sex affected rate of gain in two trials (Table 44). Barrows gained

significantly faster than gilts. No effect on rate of gain due to

protein level was observed in any trial.

Barrows responded significantly more to DES + MT than gilts.

This difference was manifested in a marked decrease in rate of gain

for hormone supplemented barrows, but essentially no change :a'

observed in gilts fed the hormone. This interaction of DES + MT with

other factors (especially sex and protein level) may be one reason

that some of the responses to DES + MT in some trials have been so

variable. This observation on gain response to DES + MT is in general

agreement with other work reported in papers mentioned in the litera-

ture review. Gain response to this combination of hormones has been

erratic at best, and it may be that the response varies with experi-

mental conditions.

Average Daily Feed Intake

Feed intake is one of the most variable parameters in animal

research. Daily feed consumption can be affected by a variety of

factors, including hormone supplementation, sex, and protein level.

In this experiment there was a significant reduction in feed intake

attributed to DES + MT in the second and fourth feeding trials (Table

44).. In the other trials there was a marked trend toward reduced

feed intake due to hormone, but the effect was not significant. There

was a significant hormone x sex interaction in Experiment 178-B.

This pattern has been noted by other workers (Wallace et al., 1967;

Beacom, 1963) who reported that feed intake in gilts was unaffected by

hormone supplementation, but was markedly decreased in barrows when

DES + MT was added to the ration. In this experiment sex also in-

fluenced daily feed intake significantly in the last feeding trial

(Table 44). Barrows consumed significantly more than gilts in

this trial.

The observed trend toward decreased feed intake was rather con-

sistent in this study, and has also been reported by numerous other

workers. Either DES or MT fed alone is capable of eliciting the re-

sponse (Dinusson et al., 1951). The feed intake reduction is most

probably one of the factors contributing to reduced rate of growth

and increased feed efficiency reported in many of the trials involving

hormone supplementation.

Feed Conversion Efficiency

The feed conversion efficiency ratio (feed/gain) was significantly

improved by DES + MT in the same 2 trials which showed a significant

decrease in feed intake caused by the hormone. Neither sex nor pro-

tein significantly influenced feed efficiency in any trial conducted

in this experiment.

It is probable that the decreased feed intake due to hormone

was responsible for this increased efficiency observed in the same

experiments. Dinusson et al. (1951) and Heitman and Clegg (1957)

reported improved efficiency due to supplementation with DES.

Wallace et al. (1967) reported that increased feed conversion

efficiency due to DES + MT was manifested most at higher protein levels.

This Is in agreement with the work of Baker et al. (1967), who re-

ported similar findings.

Opposite results were observed in this study. There were 2 trials

in which protein level varied (Experiments 178-A and B). No signifi-

cant differences in feed efficiency were observed in Experiment 178-A,

but in Experiment 178-B there was a more marked improvement in

efficiency due to DES + MT in pigs fed the low protein diet than in

those fed the high protein diet.

In Experiment 178-D, efficiency was improved more by DES + MT

in gilts than in barrows.

The Effects of Hormone, Protein, and Sex on the
Carcass Characteristics of Swine

Dressing Percentage

Dressing percentage was affected by hormone in only the first

trial of this series. Beacom (1963) reported no change in dressing

percentage due to DES or a combination of estradiol and testosterone.

Other workers have obtained similar results.

There was a significant 3 factor interaction (protein x hormone x

sex) observed in the first trial, which influenced dressing percent.

When this interaction was graphed (Figure 1) it was evident that bar-

rows and gilts responded in an opposite manner to hormone supplemen-

tation and protein level. Differences in carcass leanness in barrows

and gilts fed different protein levels are well documented. It may

have been this effect which was responsible for the 3 factor inter-

action. Due to this 3 factor interaction, it was impossible to make

inferences concerning any of the main effects on dressing percent.

Percent Lean Primal Cuts

Percent lean primal cuts are a good index of overall carcass

leanness. Lean primal cuts were increased significantly due to DES +

MT in 3 out of 4 trials (Table 44) in this study. Increased protein

level was also responsible for an increase in percent lean cuts in

the first trial. This increase in percent lean cuts due to DES + MT

was probably an additive effect accumulated in increments in each of

the 4 lean cuts. Percent ham was not changed by DES + MT in any

trial, but was significantly greater in gilts than in barrows in

Experiment 178-A. In addition, there was a significant hormone x sex

interaction which affected percent ham in Experiment 178-D. Gilts

did not respond to DES + MT, while barrows showed a significant in-

crease in percent ham due to the hormone. There was a significant

hormone x sex interaction influencing percent loin in the first two

trials (Figures 4 and 18). In both cases, gilts showed a very slight

negative response in percent loin to. the hormone supplement, while

barrows responded with a marked and significant increase in loin yield.

Percent picnic shoulder was significantly increased by DES + MT in

2 trials, as was percent Boston Butt.

When the cumulative effects of these increases are summed together

into percent lean primal cuts, the result is a consistent increase of

lean cuts in the range of about 2 percent. There were 2 significant

hormone x sex interactions which showed a differential response in per-

cent lean cuts due to DES + MT in barrows and gilts (Figures 2 and 17).

Barrows responded more markedly than gilts to hormone supplementation

influence on percent lean cuts.

In general, this response in lean cuts is a good indication that

there is a significant improvement in carcass leanness due to DES +

MT. This observation is in agreement with the results reported by

Wallace et al. (1967), Baker et al. (1967), Beacom (1963), and Door-

nenbal and Frankenham (1969). Hale and Johnson (1970) also reported

Sncrsin Ican cuts du- to hormone zupplementation.

Backfat Thickness

Workers cited in the preceding section and in the literature re-

view have reported that, accompanying the increased yield of primal

cuts usually stimulated by DES + MT, there is nearly always a simul-

taneous decrease in backfat thickness. Results obtained in this

investigation corroborate these findings. Backfat thickness was sig-

nificantly reduced by DES + MT in 3 out of 4 trials. Protein level

also tended to affect backfat in the first trial. Increased protein

level decreased backfat significantly. In the second trial, both

protein and sex interactions with hormone affected backfat thickness

response (Figure 19). From the graphs of these interactions it is

apparent that DES + MT reduced backfat in barrows and in pigs fed the

low level of protein.

These results are logical, since gilts are usually leaner than

barrows to start with, and pigs fed high levels of protein are

leaner than those fed low levels of protein; therefore, the gilts

and high protein fed pigs would respond less in backfat thickness

reduction when DES + MT was fed.

Loin Eye Area

Loin eye area was not affected by DES + MT in any of the trials.

This is in agreement with the work of Wallace et al. (1967). Baker

et al. (1967) reported an increase in loin eye area due to DES + MT

only at superadequate levels of protein.

Carcass Length

Carcass length was affected by hormone in only one trial. Gilts

fed DES + MT at the 12 percent protein level had significantly longer

carcasses than those fed the 12 percent protein basal ration. No

other inferences concerning main effects on carcass length are mean-

ingful due to the significant 3 factor interaction observed. There

was a non-significant trend toward increased length due to DES + MT

in the other trials. Baker et al. (1967) also reported an increased

length of carcass due to DES + MT.

Carcass Subjective Measurements

None of the trials showed any significant response to DES + MT

in loin eye marbling score, loin eye color score, loin eye firmness

score, or loin tenderness score. These responses were similar in all

4 trials. Loin meat aroma and flavor scores for incidence of boar

odor were significantly increased in all 4 trials. There appeared to

be a definite increase in the incidence of boar odor and flavor in

the meat of pigs fed DES + MT. This boar odor increase was strongly

manifested in the first 2 trials, and'was seen to a lesser extent in

the last 2 trials. In the first 2 trials, a number of carcasses were

condemned for boar odor incidence, but in the last 2 trials, eating

quality of the meat of most pigs was judged acceptable even though

a slight boar odor in meat of treated pigs was detectable by a trained

taste panel.

These results are in agreement with those reported in numerous

papers cited in the literature review. 'WallacL etL ol. (15U7) found

a very strong boar odor in meat of pigs fed DES + MT. The odor prob-

lem seems to be complex, and is affected by other factors than hormone

supplementation (Martin, 1968). There seems to be no doubt, however,

that methyltestosterone is the hormone responsible for stimulation of

the production of this odor and flavor.

Chemical Composition of Loin

In the last 2 trials, the chemical composition of samples of

lean longissimus dorsi was determined. Percent dry matter in the loin

was significantly less for pigs fed DES + MT in Experiment 178-C.

Percent protein in loin was also significantly increased by DES + MT

in this experiment. Fat content was also reduced non-significantly

in hormone fed pigs in this trial. Results differed markedly in the

next trial. There was no significant difference observed between

treatment groups in percent dry matter. Percent protein in the loin

was significantly decreased by DES + MT, and percent fat was signifi-

cantly increased by hormone. This same trend was apparent in differ-

ences between barrows and gilts, the loins of barrows being signifi-

cantly fatter and having less protein than those from gilts. The

difference in these responses between the two trials is difficult to


In Experiment 178-C, loin percent dry matter and protein and

pork chop aroma score were the only responses observed to be signi-

ficantly different due to treatment. None of the carcass leanness

parameters were significantly different, yet loins of treated pigs

were significantly leaner as evidenced by chemical analysis. On the

other hand, in Experiment 178-D, the major carcass leanness indices

(percent lean primal cuts and backfat thickness) were significantly

improved by hormone supplementation, yet loin meat from treated pigs

contained significantly more fat and less protein than meat from con-

trol pigs. These results are in conflict with those reported by

Doornenbal and Frankenham (1969), although the results of Experiment

178-C agree with their findings. Plimpton (1966) reported that 70

kg boars implanted with 96 mg of DES had (at slaughter weight) a

greater percentage of moisture and a lower percentage of fat in the

longissimus dorsi than did control boars. The pigs in Experiment

178-D which received DES + NT had every indication of being leaner,

meatier animals than the control group. Loin eye marbling score was

Increased non-significantly by DES + MT in this trial, and this in-

crease in marbling is probably the cause of the increased fat content

and decreased protein content observed in longissimus dorsi samples of

treated pigs. DES + MT may decrease depot fat to a greater extent

than intramuscular fat.

The Effects of DES + MT on the
Nitrogen Retention of Growing-Finishinq Swine

There is some evidence (D. H. Baker, unpublished data) that DES

+ MT stimulates increased nitrogen retention in swine. Baker studied

the nitrogen retention patterns of 6 barrows in a cross-over design

and found that in every case feeding DES + MT resulted in an increased

nitrogen retention in these barrows. An increase in protein anabolism

due to DES alone and MT alone is well documented in other species

especially in ruminants in the case of DES. Certainly one might ex-

pect to find an increase in nitrogen retention due to therapy with

known potent anabolic drugs.

Results of the two metabolism trials performed in this investi-

gation conflict with this. There was a slight but non-significant

decrease in nitrogen retention of barrows fed DES + MT in two trials.

Other parameters were also not significantly different. These results

are opposite those of Baker's unpublished data. Several explanations

of this difference come to mind. The pigs in this trial were full-

hand-fed a 14 percent protein diet twice daily, while Baker used 16

percent protein, and restricted daily feed intake to 1.8 kg per day.

In Experiment 178-E the pigs consumed less feed than did Baker's pigs,

but the feed intake of pigs in Experiment 178-F was greater than that

of Baker's pigs. The depression in feed intake in Experiment 178-E

was attributed to high ambient temperature. It has been demonstrated

(Wallace et al., 1967; Baker et al., 1967) that pigs fed DES + MT

respond to the hormone more markedly at higher protein levels. It

may have been that the pigs in Experiments 178-E and F did not consume

sufficient protein to allow normal nitrogen retention.

This overall depression in feed intake observed in all pigs in

the metabolism trials may have affected the response to DES + IT,

since 65 kg pigs under normal conditions would consume about twice

as much feed as did these pigs, which were confined in metabolism

crates. In addition to this overall decrease in feed intake attributed

to stressful experimental conditions, the pigs fed DES + MT showed

the typical depression in feed intake characteristic of hormone fed

pigs. This difference in feed intake between control and treated pigs

may have caused the slight reduction in nitrogen retention in pigs

fed DES + MT, although the feed factor was accounted for in calculations.

Heat and confinement stress may have been directly responsible for

the lack of significant responses to DES + MT.

On the other hand, all pigs in these trials exhibited a positive

mean nitrogen balance which would indicate that some anabolism was

taking place. In fact, all pigs on both treatments did show a weight

gain from the initial to the final weighing. Growth (protein synthesis)

may have been occurring at the maximum possible rate under the experi-

mental conditions. If this was the case, the body protein stores of

the pigs may have been filled; therefore, no further anabolism under

prevailing conditions might be expected to occur in response to OES + MT.

Other workers (Leathem, 1956; Applezweig, 1962) report that

when the body protein stores are filled, little or no anabolic response

to hormone therapy occurs. Robinson and Singleton (1966) were able

to demonstrate an anabolic response in pigs fed a low protein diet,

but not in pigs fed a high protein diet, when an anabolic steroid

hormone was administered.

Variation in feed intake between individual pigs and variation

from day to day in the same pig were both considerable. This was

reflected in a marked variation in nitrogen retention between pigs

and within pigs between days.

A test of the variation between pigs is available. Dividing

sampling error mean square into experimental error mean square

(Tables 40 and 42) gives an F with 3 and 40 degrees of freedom. In

both of the metabolism trials conducted in this study, there was a

significant variation in nitrogen retention between experimental

units (pigs), regardless of block or treatment.

Certainly there are factors which are often beyond experimental

control which can influence the results of a trial. The nitrogen

balance experiments conducted in this study do not give evidence

for a protein anabolism due to DES + MT, despite the fact that a

response favoring increased nitrogen retention might be expected

from the use of such compounds.

The Effects of DES + MT on the
Excretion of Urinary 17-ketosteroids in Swine

Since one of the hormones fed in these experiments, methyl-

testosterone, is excreted in a conjugated ketone derivative form in

urine, a determination was made in the two metabolism trials to de-

tect 17-ketosteroids in urine. These substances are metabolic end

products of steroid hormones of all types.

A significantly greater amount of 17-ketosteroids was excreted

by pigs fed DES + MT in the first metabolism trial. No significant

difference due to treatment was observed in the second trial, although

there was a trend toward a lower excretion of 17-ketosteroids in

the treated pigs. Pigs in Experiment 178-E did not excrete as much

total urine per day as did those in Experiment 178-F. It was noted

that the 17-ketosteroids were more difficult to detect in dilute

urine than in concentrated urine. There also appeared to be great

individual variation among pigs with regard to urinary output and

17-ketosteroid excretion.

Adrenal hormone output influences output of 17-ketosteroids, and

it may be that the individual metabolisms of the pigs accounted for

more variation than did the hormone present in the diet. Pigs were

consuming only 3.5 to 5.5 mg of hormone per day.

The feed intake of barrows differed between the two metabolism

trials, and this factor may have influenced the results obtained.

Dorfman and Shipley (1956) state that in humans the normal daily ex-

cretion of urinary 17-ketosteroids varies with age, sex, stress

factors, and endogenous hormone therapy. In this study, DES + MT

did not appear to consistently affect the excretion of 17-keto-

steroids in urine of swine.

General Comments

Work reported by researchers studying DES and MT indicates that,

fed alone or in combination, these humoral substances affect the

performance and carcasses of pigs. The exact mechanism of action

remains unclear at this time. There is reason to believe that some

of the response in carcass leanness attributed to DES + MT may be

due to the reduced feed intake commonly observed when this combina-

tion of hormones is fed to pigs. The improved lean to fat ratio

resulting when pigs are fed on an energy restricted diet is well


Baker et al. (1967) reported that loin eye area response to DES +

MT is generally improved at higher levels of protein; they postulated

that this points to a protein-anabolic action. This alone, though,

cannot explain all the common responses to DES + HT. The reduction

in backfat thickness coLmmonly seen has been attributed to a possible

antilipogenic action of DES + MT. Decreased backfat thickness may

also be a factor in the increased yield of lean primal cuts observed

in 3 trials in this investigation and by other workers. A change in

rate of deposition of either protein or fat would be reflected in the

leanness criteria used in these experiments.

In regard to the stimulation of increased boar odor incidence,

the value of feeding DES + MT is questionable. Some treated pigs in

the first 2 trials exhibited very undesirable odor and flavor in

the meat; however, in the second 2 trials the meat odor and flavor

was acceptable for most pigs even though some incidence of boar odor

in treated pigs was evident to the trained taste panel. The boar

odor present in the carcasses of some pigs in Experiments 178-A and

B was strong enough to cause condemnation of some carcasses; however,

no carcasses were condemned for odor or flavor in Experiments 178-C

and D.

A possible explanation of this might lie in the formulation of the

hormone premix. Researchers at Eli Lilly and Company discovered that

there was a cis-trans isomerism in diethylstilbestrol hitherto un-

known (Herb Brown, personal communication). This isomerism resulted

in a racemic mixture of cis DES (60%) and trans DES (40%) after a

period of time, even though the manufacturing process produced all

trans-DES. Cis-DES was found to be biologically inert in estrogenic

activity, w.hi!e the trans isomer :.a very active. Both forms, however,

showed up in full amount upon chemical analysis. A new stabilized

form of DES was developed which contained 95 percent of the trans

isomer and which would not racemize to the cis form. The first 2

trials were performed using the old type hormone supplement, while

the remainder used the newer stabilized form. It was postulated that

the estrogenic activity of the DES was not sufficient to balance the

androgenic effects of the methyltestosterone in the old type hormone

mixture. This may have caused the strong boar odor and flavor ob-

served in some pigs in the early trials. Incidence of boar odor was

much lower in the later trials using the high-trans stilbestrol mix-


Numerous hormone x sex interactions were observed in all 4 trials.

In general, these interactions were manifested in a different'degree

or direction of response in barrows and gilts. This sex difference

in response to hormone supplementation is probably due to the fact

that barrows have no endogenous source of sex hormones other than the

small amounts produced in the adrenal cortex, whereas gilts have an

ovarian source of natural steroid sex hormones. Doornenbal and Frank-

enham (1969) also observed hormone x sex interactions and concluded

that different proportions of sex steroid hormone supplementation for


barrows and gilts would be necessary to achieve equal responses in

both sexes.

In these experiments, the hormone combination affected perfor-

mance and carcass quality more in barrows than in gilts.


Four feeding and carcass trials and 2 metabolism trials were

conducted to determine the effects of DES + MT on growth, carcass

quality, and nitrogen retention in groi-ng-finishing pigs.

Average daily gain was reduced by hormone supplementation, as

was feed intake. Feed efficiency was generally improved by hormone.

There was a marked and significant trend toward increased carcass

leanness, manifested in a decreased backfat thickness, increased

length, and increased percent of lean cuts, both individually and as

the 4 lean primal cuts. Loin eye marbling, color, firmness, or ten-

derness score were not affected by DES + MT. Chemical composition

of longissimus dorsi was significantly but not consistently affected

by hormone supplementation.

Hormone supplementation produced a significant increase in the

Incidence of boar odor in meat of pigs. This odor was judged un-

desirable and in many cases in early trials, unacceptable.

In later trials, however, the incidence of sex odor was detect-

able and was present to a degree such that the eating quality of the

meat was reduced in some, but not all, cases.

Two metabolism trials failed to show any significant differences

in nitrogen retention, feed intake, weight gain, or digestibility of

dry matter and nitrogen between hormone treated and control pigs.

Excretion of 17-ketosteroids in urine was not consistently affected

by hormone.

A possible protein anabolic effect or antilipogenic effect was

postulated to explain the mode of action of DES + MT in increasing

carcass leanness. It was also noted that the reduced feed intake

common to administration of this combination of drugs was possibly

involved in the carcass leanness response.

As part of the study, the effects of protein level and sex were

also investigated. In general, increasing protein level resulted in

improved performance and carcass quality. Gilts had superior carcasses

to barrows, and were more efficient but gained more slowly than

barrows. Sex and protein level were found to interact with each other

and with DES + MT in influencing many performance and carcass traits.

It was concluded that the mode of action of DES + MT in improving

carcass leanness was unclear. Furthermore, all the effects of DES +

MT on performance and carcass quality in swine are not manifested


The value of DES + MT in improving carcass leanness is fairly

evident, but the problem of boar odor which may appear in the meat

of pigs fed this hormone combination remains unresolved.

This investigation has attempted to define the effects of di-

ethylstilbestrol and methyltestosterone (and their interactions with

other factors) on the performance and carcass quality of finishing


It is the feeling of the author that the effects are fairly well

defined in this ..,'oy, and by other work cited in the literature

review. Future research work on this problem ought to be concen-

trated on defining the mode of action of DES + MT in the body of the

pig. Another area of research which needs to be investigated is

the boar odor problem; some means of reducing the incidence of boar

odor in pigs fed DES + MT may be available. Perhaps another practi-

cal approach to the problem would be the feeding of boars to market

weight, using only a DES supplement to delay or prevent the develop-

ment of the natural boar odor.

At this time, however, DES + MT does not appear to be a

consistently practical approach to improving performance and carcass

quality in pigs, due mainly to the possibility of producing unde-

sirable odor and flavor in meat.



Table 1. Experiment 178. Composition of diets

Protein levels, %
Ingredient 12 14 16

Ground yellow corn (8.9% C.P.) 89.05 84.05 79.05
Solvent soybean meal (50% C.P.) 8.00 13.00 18.00
Defluorinated phosphate (32% Ca; 18% P) 1.80 1.80 1.80
Calcium carbonate (38% Ca) 0.50 0.50 0.50
Iodized salt 0.50 0.50 0.50
Trace mineral premix 35C-73a 0.05 0.05 0.05
Vitamin premix (U.F.)b 0.05 0.05 0.05
Chemotherapeutic premixC,d 0.05 0.05 0.05

Totals 100.00 100.00 100.00

a The composition is shown in Table 3.
b The vitamin fortification is shown in Table 4.
c Basal diets contained tylosin phosphate, 11.0 mg/kg.
d Hormone diets contained 2.2 mg/kg each of diethylstilbestrol
and methyltestosterone and 11.0 mg/kg of tylosin phosphate.

Table 2. Experiment 178. Calculated analysis of diets

Protein levels, %
Calculated analysis 12 14 16

Protein, % 11.93 13.99 16.04
Energy, met. cal./kg 3208 3166 3123
Calcium, % 0.80 0.80 0.80
Phosphorus, % 0.62 0.62 0.62
Vitamin A, I.U./kg 5700 5723 5557
Vitamin D3, I.U./kg 441 441 441
Riboflavin, mg/kg 12.5 12.5 12.5
Niacin, mg/kg 215.4 215.4 215.4
Choline, mg/kg 800.0 800.0 800.0
Vitamin B12, ug/kg 11.0 11.0 11.0
Pantothenic acid, mg/kg 20.0 20.0 20.0

Table 3. Experiment 178. Composition and contribution of trace mineral
premix 35C-73


% in premix

Level in feed when added at 0.05%

Manganese 10.0 50.0
Zinc 10.0 50.0
Iron 10.0 50.0
Copper 1.0 5.0
Cobalt 0.1 0.5
Iodine 0.3 1.5

a Supplied as manganese sulfate, ferrous sulfate, ferrous carbonate,
iron oxide, copper oxide, cobalt carbonate, potassium iodide,
and zinc sulfate.

Table 4. Experiment 178.


of vitamin premix


Contribution per kg diet

Riboflavin 6.6 mg
Niacin 22.1 mg
Pantothenic acid 13.2 mg
Choline chloride 88.2 mg
Vitamin B12 11.0 pg
Vitamin A 2756 I.U.
Vitamin D3 441 I.U.

Table 5. Experiment 178. Dry matter and protein analysis, % of diets

Protein levels, %
Analysis 12 14 16

Dry matter, % 85.84 86.93 85.53
Crude protein, % (d.m. basis) 12.71 14.58 16.44

Table G. Experiment 178.

Code for marbling score of longissimus dorsi
at 10th rib

Amount of marbling


Devoid 0
Practically devoid 1 2 3
Traces 4 5 6
Slight 7 8 9
Small 10 11 12
Modest 13 14 15
Moderate 16 17 18
Slightly abundant 19 20 21
Moderately abundant 22 23 24
Abundant 25 26 27
Very abundant 28 29 30
Extremely abundant 31 32 33

Table 7. Experiment 178. Code for color of longissimus dorsi at
10th rib

Color of lean Code

Very dark I
Dark 2
Greyish pink (ideal) 3
Lightly light in color 4
Chicken meated very light 5



Table 8. Experiment 178. Code for firmness of longissimus dorsi at
10th rib

Firmness of lean Code

Medium hard 2
Medium soft 3
Soft 4
Oily 5

Table 9. Experiment 178. Code for boar odor and flavor score

Degree of boar odor or flavor Code

Slight 2
Moderate 3
Strong 4

Table 10. Experiment 178-A. Experimental
of animals

design and distribution

Treatment factor 1 2 3 4

DES + T + +
Protein level, % 16 16 12 12
Number of pigsa 18 18 18 18

a Each lot consisted of 9 barrows and 9 gilts.

Table 11. Experiment 178-A. Summary of feedlot performance

16% C.P. 16% C.P. 12% C.P. 12% C.P.
Criteria Basal DES + HT Basal DES + MT

Average daily feed, kg 2.62 2.53 2.86 2.74
Average daily gain, kg
(66 days) 0.75 0.75 0.81 0.75
Feed/gain 3.50 3.36 3.54 3.64

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