EFFECT OF F‘JRCED EXERCISE UPON REPRODUCTIOI-I

OF THE DAIRY BULL

EFFECT OF FORCE EXERCISE UPON EPRODUCTION

JACK WILLARD SLYDER

N

Submitted to the Graduate School of Michigan
State College of Agriculture and Aoolied
Science in partial fulfillment of the
requirerents for the degree of

EASTER OF SCIENCE

Deoertment of Dairy

1950

THESIS

 

*.~—

ACKIOULEDGKEJTS

The author wishes to express his sincere appreciation
to Dr. Earl Teavcr, Professor of Dairy Husbandry, for mak-
ing this study possible; to Dr. C. F. Huffman, Research
Professor of Dairy Husbandry, for his guidance in conduct-
ing these investirations; to Dr. N. P. Ralston, Associate
Professor of Dairy Husbandry, for his guidance and critical
reading of this manuscript.

The writer is esoecislly grateful to Kr. A. C. Ealtzer,
Se retsry—Treasurer, of the hichigan Artificial Breeders'
Association for his aid in the plan of the experiment and in
compiling the experimental data by making many records avail-
able. My sincere regards are extended to the Eichipan
Artificial Ereeders' Board of Directors for providing the
Eichigan Artificial Breeders' Association Fellowship thus al-
lowing me to pursue graduate studies in Dairy Cattle Production.

Gratitude is also eroressed to Mr. Fred Dombroske, Plant
Tanager, of the association for carrying out many difficult
tasks in selecting the experimental animal and collection of
data. Also my thanks are extended to the several other indi—
viduals of the association who cooperated so wholeheartedly
in this study.

Anoreciation is exoressed to W. D. Eaten, Professor of
Hathematics, for his assistance in preparing the statistical

analysis of the data.

Z37fé?

TABLE OF COFTEETS

IKTRODUCTION..... ............................ ...........

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Characteristics of Spermatozoa.. ................ .....

Normal morphology... ..... ......

Abnormal morphology.. ..... ........

Characteristics of Semen..........

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Concentration.....

hotility. ....................... ....

Hydrogen-ion concentration.....

Hyaluronidase.....

Preservation of Semen....

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Diluters...... ..... . .......... . ....... ............

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Factors Affecting Quality of Seaen......

Season and temperature......... ..... ..............

Age and frequency of ejaculation..................

Li1oid0.. ......... C ....... O ....... 0..

The Role of the Endocrine System in Fertility........

Endocrine interactionsv. .................... ......

Effect of the anterior pituitary....

Effect of thyroid gland....... ............... .....

Nutritional Factors..

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Selection of Ani als................................ 57
Feeding and Fanagement.............................. 57
Exercising Procedure................................ 61
:tethod of Semen muslin; 62

Procedure of Baking Semen S ears for
i'orph010g108bl StudieSooooooooo00000000000000.0000. 63

method of Counting Spermatozca...................... 65
Weights of the Bulls................................ 66
Evaluating the Degree of Libido..................... 67
Observations on Appetite and General Activity....... 67

XPERIE'E1:TALRESDYLTSOOO.OOOOOOOOOOOOOOOOOOOOO...00.0.... 68

III-1

Breeding Efficiency................................. 63
Seven Characteristics............................... 77
Volume............................................ 77
Total Spermatozoa................................. 86
Initial notility.................................. ,5

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Types of Abnorval Snernatozoa......................... 113
Coiled tails........................................ 113
Taillese Boermatozoa................................ 122
Broken necks........................................ 122
True abnormal enermetozoa........................... 125

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BIELIOGRAPHY............................................... 133

 

 

 

 

 

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INTRODUCTION

The number of cows enrolled in artificial breeding
associations approached the three million mark in 1999 which
indicates that one cow in nine in the United States probably
will be bred artificially in 1950. Compared with January,
1939, this is an increase of 372,322 or 576.3 percent in num—
ber of herds and 2,819,991 or 2,651.6 percent in number of
cows. I

This method of mass improvement for dairy cattle has di-
rected attention toward the many factors affecting fertility.
Fundamental research on artificial insemination procedures
and their practical applications have increased the average
number of cows served by each bull in the associations.

In artificial breeding, extending the use of older bulls
with creditable breeding records has increased the average
service age and made it imperative that management practices
be evolved which will prolong the useful life of desirable
sires.

Up to the present, increased dilution rates probably
have contributed most to the wide spread use of good sires.
While the experience of those concerned with the reproduc-
tive efficiency of bulls suggests that exercise is beneficial
to their breeding abilities and fertility, the reports in the
literature give only limited quantitative data on the quan-
tity and quality of semen and on fertility.

Various investigators have indicated that proper exercise

contributes to the physical well-being of the bull and in-
creases spermatogenic activity. Bartlett and Perry (19)
exercised three bulls at the rate of two and one—half miles
per hour for one hour each day for one month. The volume of
semen increased 51 percent as compared to the previous month.
Woodward (160) reported that exercise at two and one—quarter
miles per hour for 30 minutes daily greatly diminished the
time of service with a slow bull.‘ It was found that exercise
increased motility and longevity of the spermatozoa. Hamilton
and Symington (65) observed that daily exercise increased the
volume of the ejaculate, sperm concentration and motility.
The lower quality of semen obtained during February and March
by Weatherby and associates (151) was believed to be due to
lack of exercise during these months. Lepard and co—workers
(87) noted no significant differences between exercised and
non-exercised sires in the factors of morphology, concentra-
tion of the Sperm, and viability of the sperm at h.5° C.
The volume of semen showed a slight but insignificant advan-
tage to bulls receiving exercise. Conception rates of the
two groups followed the same general trend. This study only
shows the value of exercise on the amount and quality of
semen as determined by semen characteristics for a sixteen
weeks' trial.

host of the above mentioned workers measured the effect
of exercise on bulls only by laboratory tests presumably de-
signed to indicate the quality of semen. In spite of the

findings favorable to exercise, many of the larger bull studs

have operated over a period of years in which the bulls have
received limited exercise (movement in stalls). This ques-
tion of the value of exercise for bulls to produce good quan-
tities of semen of acceptable quality has become one of wide-
spread interest.

The conception rates measured as "non-returns" for 60—90
days have been increasing due to improvement in collection,
processing, storage and shipment of semen. Therefore, any
procedure that will further increase the rates are diligently
pursued. An eXperiment was designed to investigate the in-
fluence of forced exercise of dairy bulls on semen character-
istics, general well being of the animals, and primarily on

conception rates, "non-returns" for 60-90 days.

REVIEV OF LITERATURE

The reproductive processes of the dairy bull are intric-
ate functions affected by many interrelated forces. To en-
tirely separate and discuss them as separate entities is im-
possible. However, in this thesis, the review has been
limited to spermatogenesis and related factors from an arti-
ficial insemination viewpoint.

Unless otherwise indicated, this review of literature
pertains to the reproduction of the dairy bull. Herman and
Swanson (69) and Anderson (13) have made extensive reviews
concerning the variations in dairy bull semen with respect to

its use in artificial insemination.
Characteristics of Spermatozoa

Normal hor hol e

   

The normal spermatozoon of the bull is a slender motile
flagellate cell having a head, neck, body and tail. When
stained, it is found to consist mainly of a compact structure—
less mass of deeply staining chromatin carrying the hereditary
factors.

Anderson (1%) gave the following measurements for the
various parts of bull spermatozoon: head length -- 5 u.,. head
width —_ 2 u,,. and tail length - 32 u.. He states that it

contains little or no cytoplasm. The head of the spermatozoon

of the bull, which is somewhat similar to the sperm of most
domestic animals, is oblong or broadly elliptical and
appears blunt at the end.

Reed and Reed (113) confirmed the work done by Clark on
the observations of bull spermatozoa made by the electron
microscope. These workers found the existence of a proto-
plasmic cap and a brush-branched tail tip. In addition, a
certain number of organisms found in every field revealed
heavy granulation throughout the protoplasmic cap. The gran-
ules were approximately 0.25 u,. in diameter and when photo-
graphed, gave the appearance of enlarged micro-photographs
of intestinal villi. Since the granules appeared to encroach
on the spermatozoon head, these authors believed this was due
to the cap overlying the crescentic anterior border of the
head. They suggested that these granules may represent age
changes in the cells.

Savage and associates (125) investigated the relation—
ship between the head length of bull spermatozoa and fertil-
ity. They found that in bulls of good fertility that the
head length showed normal or almost normal distribution, and
these workers maintained that the coefficient of variation
of head length provides a good indication of fertility. In
normal bulls, the coefficient should not exceed four accord-
ing to Lagerlof (84). He considered bulls with a coefficient
of four and under as fertile, and those with a coefficient

4.5 and over as of reduced fertility.

Abnormal morphology

Abnormal dairy bull spermatozoa have been placed into
various classifications by investigators in this field.

Addie (l) recognized the following types of abnormal sperma-
tozoa, (1) those differing from normal in size, that is,
giant and dwarf forms, (2) those with two heads or two tails,
(3) those with abnormally shaped heads, such as general
tapering of the head, (4) those with loose heads, (5) those
with abnormalities in the middle pieces and (6) those with
disturbed staining capacity (staining too strongly or too
faintly).

Herman and Swanson (69) classified abnormal dairy bull
snermatozoa into the following groups in the descending order
of their occurrence: (1) coiled tails, (2) tailless, (3)
pyriform heads, (H) other head abnormalities such as damaged
heads, tapering or pointed heads, small and large heads, and
phantom heads, and (5) body abnormalities including damaged,
enlarged, filiform, beaded or shrunken middle pieces, double
tails, broken necks, and protoplasmic drops in the neck.
Bulls with poor breeding records had a relatively greater num—
ber of coiled tails and tailless spermatozoa than bulls hav-
ing a high conception rate. The percentage of abnormal sper—
matozoa varied widely within and between bulls at each fer-
tility level. The semen of dairy bulls of good, questionable
and poor fertility averaged 19.2, 24.0 and 45.8 percent re-

spectively. No particular type of abnormality seemed to be

associated with reduced fertility. These authors indicated
that the unper limit of percentage of abnormal spermatozoa
compatible with good fertility is approximately 30 percent.

Salisbury and associates (123) classified spermatozoa
into the following groups: (1) morphologically normal, (2)
true abnormals, which included such types as those possess-
ing any abnormality with respect to the shape or size of the
head, those with enlarged, abaxial, beaded or filiform
middle pieces, and those with thickened or double tails, (3)
tailless spermatozoa, (4) spermatozoa with broken necks, and
(5) spermatozoa with coiled tails. Lagerlof (84) studied
the semen of good fertility bulls. He found that the percen-
tage of abnormal spermatozoa did not exceed 18 percent (aver-
age 10 to 12 percent). One-hundred and fifty bulls of
lessened or arrested fertility showed 20 percent or more ab-
normal spermatozoa.

Addis (1) reported that three sterile bulls which he ex-
amined were normal as far as volume, appearance, concentration
and motility of the semen were concerned, but that #0 to 50
percent of the spermatozoa were abnormal. Generales (55)
stated that good fertility could be eXpected if the percentage
of abnormal spermatozoa was not over 25 percent. When it
reached 60 percent, the animal was sterile. Similar results
were reported by Sciuchetti (127).

Anderson (11) found abnormal spermatozoa averages of 8.1,
13.1 and 17.6 percent respectively in fertile bulls, bulls of

reduced fertility, and in sterile bulls. In a further study,

Anderson (13) showed that six bulls of high fertility gave

an average of 10.5 percent. Morphological characteristics
of 24 dairy bulls of the Holstein, Guernsey, Jersey, and
Ayrshire breeds used in the University of Nebraska's Dairy
Herd were observed monthly for a period of years by
Trinberger and Davis (1&3). They found that the bulls aver-
aged 790.5 normal sperm cells per 1,000, with a range from
276 to 968 for individual samples, and from 373 to 904.u from
the lowest to the highest average for a bull. The breeding
efficiency was 57.76 percent conception in the #83 cows bred.
Bulls with 900 normal sperm cells per 1,000 spermatozoa had
significantly better breeding records. Whereas, bulls with
less than 500 normal sperm cells per 1,000 spermatozoa had
very poor breeding records.

Davis et a1., (40) found that the percentage of a—
typical sperm in the semen from 11 fertile bulls was rela—
tively constant, average 18 percent or less. Erb and assoc-
iates (51) observed that bulls produced a greater number of
abnormal sperm during the summer months than during any other
season. Swanson and Herman (137) showed that for some bulls,
good fertilitywas maintained in spite of concentrations of
abnormal spermatozoa as high as 30 percent. They concluded
that some pathological condition must be present when the par-
centage of abnormal aperm approaches 50 percent.

In conclusion, the percentage of abnormal spermatozoa
that appears to be compatible with good fertility in the dairy

bull varies between 10 to 30 percent. However, it is not

always possible to determine the exact fertility level of
the dairy bull by using the percentage of abnormal spermato-

208..

Characteristics of Semen

Anderson (13) defines the ejaculate of a normal bull of
good fertility as an Opaque, whitish yellow fluid of milky
or milky-creamy consistency. The measurements of semen which
characterize it are empirical and cannot be discussed as
separate entities. An attempt will be made to treat each
characteristic, but to do so means that these measurements

will be relative to associated factors of semen on its produc-

tion.

Volume

The volume varies considerably in the same bull and in
different bulls from time to time. Herman and Swanson (69)
noted that in one series of 334 ejaculates collected from 50
bulls, the volume ranged from 2.5 to 5.5 ml. with a mean of
4.38 : 1.02 ml. Anderson (13) gave the average volume of the
ejaculate as 4 ml. with a range of 5 ml. to 12 ml.

It was early observed by Anderson (11), that the volume
of semen collected from sterile bulls is less than that ob-

tained from bulls of high fertility. He indicated that the

volume is usually smaller in young bulls than in adult bulls.

10

However, Swanson and Herman (69) found that the volume of
semen did not vary directly with the age of the bulls. In
general, the volume of the ejaculate varied as the size of
the bull within any one breed. A few old bulls that were
small gave much less semen per ejaculate than younger, larger
bulls. Anderson (9) noted that the volume is maintained
fairly constant over a period of five to six years, but it may
decrease as the bulls become older.

A second ejaculate collected shortly after the first is
usually larger as shown by Anderson (11). Davis and Williams
(41) and Mercier and Salisbury (94) noted a slight increase
in the volume of the second ejaculate, with little difference
between the second and third ejaculates. Lasley and Bogart
(86) observed that the volume of semen in range beef bulls
increased as the interval between collections increased.

There are indications of possible breed differences.
Anderson(9) observed that Holstein bulls gave larger ejacu-
lates than Ayrshires. Lewis (8S) found a highly significant
difference between bulls of the same breed, and also an indi-
cation that Guernsey bulls gave larger amounts of semen per

ejaculate than did Holstein bulls.

gbncentration

The total number of spermatozoa in an ejaculate (volume
I concentration) is a highly important factor in determining

the usefulness of bulls in artificial insemination.

(Ill Ill. 15!} [If]. III. I

11

A wide range of variation in concentration occurs in
both bulls of low and high fertility. Erb and co-workers (51)
noted highly significant differences between bulls for con-
centration of spermatozoa per cu. mm. Anderson (13) gives
the average number of spermatozoa as 600,000 to 1,000,000 per
cu. mm. Davis and Williams (41) noted a range from 8,000 to
nearly 2,000,000 with an average of 734,000/cu. mm.

walton and Edwards (146) showed by "exhaustion tests"
that the total number of spermatozoa for 10 collections from
14 bulls ranged from 2,880 million to 32,140 million with an
average of 14,000 million per collection. Herman and Swanson
(69) found that the concentrations of spermatozoa per cu. mm.
rank in order as follows: first ejaculate, 826,000; second
ejaculate, 635,000; third ejaculate, 357,000. Anderson (9)
reported that spermatozoa are few or absent in epididymites,
in atrOphied cases and in hypoplasia of the testes.

It would be of considerable assistance to artificial
breeding stud managers to know the approximate number of sper-
matozoa required for conception in order to make maximum use
of semen. Herman and Swanson (69) found that the conception
rate was practically independent of the amount of semen used
in inseminations when .4 ml. or more of fresh semen was used
per insemination. Salisbury and associates (117) in coopera—
tion with the New York Artificial Breeder's Co-operative di-
luted semen at a rate varying from 1:2 to 1:14. Comparable
rates of conception were obtained. Later, work by Salisbury

and Bratton (118) showed in an experiment involving 7,343

inseminations, that when sulfanilamide was added to yolk—
citrate diluter, there was no difference in fertility level
for dilution rates of one part of semen to 100, 150, 200,

300 and 400 parts of the yolk—citrate—sulfanilamide diluter.
Branton and co-workers (32) found that diluting bull semen
with egg-yolk—citrate—sulfanilamide containing 16, 12, 6, and
4 million spermatozoa per ml. resulted in 62.8, 64.0, 58.0
and 63.5 percent non-returns respectively on 30 - 60 day
basis. Statistically, these fertility levels were not sig—
nificantly different. Hot less than 0.3 ml. of diluted semen
should be used for insemination according to a study by Herman
and Swanson (69).

Four controlled experiments were conducted by Willett
(153) to study dilution levels above 1:100. A total of 11,372
services from 69 collections from bulls selected for high fer—
tility showed a downward trend with an increase in dilution
level, but none of the differences were significant. As the
number of spermatozoa decreased from approximately 12 million
to six million spermatozoa per m1., there was a drop of about
2.6 percent in non—returns per million of spermatozoa used
per insemination. There was a marked decrease in livability
of spermatozoa with increased dilution rates. Chang et a1.
(36) studied the effect of dilution upon motility of bull
spermatozoa on six semen samples from each of five bulls. The
semen was diluted 1:10 and also successively in eight differ-
ent dilutions from 1:100 to 1:12,800. Two different diluents

were used, 0.9 percent sodium chloride and 0.08 M. sodium

 

 

.lll’l.‘|lll|lr

13

citrate. The percentage of motile spermatozoa decreased
markedly in the higher dilutions.

It appears to the author that further investigations are
needed to determine the Optimum dilution rate for fertile

bull semen to insure the highest possible conception rates.

Mgtllity

Motility of Spermatozoa varies considerably. However,
in general, high motility ratings signifies good conception
rate. It is not an infallible index, but it has been the one
criterion most commonly used by successful artificial breed—
ing associations.

The motility of spermatozoa from normal, fertile bulls is
usually 70 percent and above as reported by Anderson (9). He
noted that in one series of 456 ejaculates, only three percent
had a motility of less than 70 percent. In another series of
254 ejaculates, 11 percent had motility of less than 70 per-
cent.

Herman and Swanson (137) examined 256 ejaculates from 10
bulls. They noted that initial motility varied less than any
other semen characteristic. There were striking differences
in motility ratings between bulls of high and low fertility.
Bulls with questionable breeding records were occasionally ob-
served to give high motility ratings, but on the other hand,
not all bulls which produced semen of good initial motility
were of high fertility. These workers stated that semen very

high in abnormal spermatozoa usually does not have good

 

 

Il|t lll'llllil“ ’1' I"

14

motility or viability, but if it does have good motility and
viability, it will probably give good breeding efficiency.
They concluded that semen used for insemination should show

an initial motility rating of three (75 - 85 motile sperma—
tozoa). Although semen with a low motility rating was of
lower fertility, they indicated that semen showing a progress-
ive motion of 45 percent gave nearly as high a conception rate
as semen with a higher motility rating. These data showed
that a curvilinear relationship existed between conception
rate and motility rating of the semen at time of insemination.

A study by Anderson (12) of 1,049 ejaculates during a
27 month experiment showed highly significant individual bull
and monthly differences in motility of spermatozoa. Lewis
(88) found that the average semen motility was least in July,
August and September. Anderson (13) states that occasionally
motility in the first ejaculation is poorer than in the second
or third ejaculates. Davis and Williams (41) found that in
motility, the ejaculates ranked as follows: first, with a
mean of 73 percent; second, with a mean of 75 percent; and
third, with a mean of 69 percent. Mercier and Salisbury (94)
found that in general, the second ejaculate contained more
motile sperm than the first ejaculate.

In a study of some factors affecting spermatogenesis and
fertility of dairy bulls, Lewis (88) observed a breed differ-
ence in initial motility, the Holstein breed showing a higher
initial motility than the Guernsey breed. This was especially

true in the winter and spring, but not as pronounced in the

 

\iyl1lv (111'.

’Il’lll’ll’fl

15

fall and summer.

Several workers have tried to classify the various
types of spermatozoa motility. Walton (147) recognized three
types of motility: (l) progressive, (2) rotary, and (3)
oscillatory. In addition to this classification, other
workers have used different terms to describe various other
types of movements. Rao and Hart (lll) classified the motil-
ity of bovine sperm into three main types, depending on the
vigor and direction of movement, (1) maximal motility, (2)
circular motility, and (3) convulsive motility. They stated
that under routine artificial insemination, maximal motility
is desired.

In summary, one may say that a motility of 70 percent or
more is necessary for practical use in artificial insemination.

However, semen relatively low in motility may be effective in

producing conception.

Hydrggen-Ion Concentration

 

The hydrogen-ion concentration of semen would appear to
be of general value for the appraisal of fertility in the
dairy bull according to Anderson (13). One of the earlier
estimations of the pH of bull semen was made by Tebster (150)
who found that almost all specimens ranged between 7.0 and 7.5.
Davis (39) found that the pH varied widely between semen col-
lected by massage of the seminal vesicles, the ampullae of the
vasa deferentia and by the artificial vagina. Semen obtained

by the former method yielded a relatively greater amount of

16

accessory secretions and a pH of 7.5 to 8.0 was not uncommon,
while for the latter method, the pH was ordinarily below 7.0.

Davis and Williams (41) using a quinhydrone gold elec-
trode, obtained a pH which ranged from 6.18 to 8.31 with a
mean of 6.99. Anderson (10) found a pH of 6.73 - .020 for 221
ejaculates from clinically normal bulls. Herman and Swanson
(69) observed little difference between the pH values of the
semen of bulls of good and poor fertility. The pH was prac-
tically the same for the more fertile bulls (pH of 6.47) and
the questionable bulls pH of 6.50 but was slightly higher for
the poorer breeders; this being mainly due to two bulls which
produced poor quality semen. They noted that the pH of bull
semen showed the least absolute variation next to the initial
motility.

Erb and co—workers (51) secured highly significant dif—
ferences between bulls and between months for all semen char-
acteristics except the pH. The pH of the semen of abnormal
bulls was investigated by Anderson (13). An alkaline reaction
was characteristic in typical cases of epididymitis and bulls
with small testes. The alkalinity was associated with a de-
crease in concentration or absence of spermatozoa.

Anderson (10) noted that when two ejaculates are collec-
ted, one after the other, from fertile bulls, the second ejac-
ulate usually has more acid than the first. In general, this
change in reaction is associated with greater concentration
and higher motility of the second ejaculate. Swanson and

Herman (135) in their study of the correlation between some

17

characteristics of dairy bull semen and conception rate found
little practical value in making routine pH determinations.
The correlation between conception rate and pH of the semen
was not significant. The pH of the semen was significantly
lower in the summer than in the fall, as reported by Swanson
and Herman (136).

Semen characteristics presented by the foregoing authors

are summarized in Table I.

Evalugonidase

:-

Spermatozoa movements have been credited with partially
erroding the cumulus oophorous and penetrating the corona
radiata, zona pellucida and the vitamins membrane of the ovum.
Recent work has indicated that an enzyme,hya1uronidase, pres-
ent in sperm aids the process of fertilization by liquefying
the gel, thus helping to disperse the cumulus cells surround-
ing the ovum.

It has been shown by McClean (90) that some species of
pathogenic bacteria produce a spreading factor which markedly
increases the permeability of the skin to injected fluids.

A similar action is accomplished by a heat labile extract of
mammalian testes, McClean (91) and Pincus and Enzmann (110).
Swyer (138) found a close correlation between hyaluronidase
content of the semen and number of apermatozoa in rabbits,
bulls, boars and men. No correlation was evident in the case

of dogs and fowls. The fact that semen from cryptochids con-

18

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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tains no hyaluronidase indicates that it is secreted by the
seminifercus epithelium rather than by the accessory glands.

A study by McClean (91) and Rowlands (116) showed that the
hyaluronidase content of the semen was related to the total
number of spermatozoa in the sample. Thus, these authors sug-
gest that it is reasonable to assume that some cases of star-1
ility or low breeding efficiency could be due to insufficient
spermatogenesis, with the result that the hyaluronidase present
was reduced to such an extent that the cumulus cells surround-
ing the ovum were not dispersed and the relatively few Sperm
present were unable to penetrate to the ovum.

In line with this suggestion, Rowlands (116) conducted an
experiment in which hyaluronidase was added to various concen—
trations of rabbit spermatozoa. In these studies the treated
semen required only one sixth as many spermatozoa to produce a
50 percent response when compared to the semen to which no
hyaluronidase was added. Chang (37) has also studied the ef-
fect of adding hyaluronidase to rabbit semen containing the
minimal number of sperm necessary for fertilization. Under
his conditions, the addition of the hyaluronidase did not in-
crease the fertilizing capacity of the sperm. Kurzrok (82)
found that in normal human semen the hyaluronidase content in-
creases with sperm concentration up to 100 million sperm cells
per cc. The hyluronidase content did not appear to be related
to the morphology, motility or percent motility of the sperm
in this study.

The source of hyaluronidase in semen has been studied by

20

several investigators. IBergenstal and Scott (23) have reported
that hyaluronidase is probably derived from the sperm cell
itself or is very closely associated with them. No hyaluroni-
dase was found in prostatic and seminal fluids of humans and
dogs although it was recovered from the testes. The hyalur-
onidase content of homogenized semen was at its peak at or
shortly after ejaculation. However, in whole semen, the con-
tent gradually increases with time.

The Question of whether hyaluronidase is released into
the semen by live sperm or is diffused only by moribund sperma-
tozoa has been studied by Swyer (138), Kurzrok and associates
(83) and Johnston and co—workers (75). The evidence appears
to indicate that hyaluronidase is released into the seminal
fluid by dead spermatozoa. Swyer (138) observed that freezing
or otherwise mistreating sperm increased the amount of hyalur-
onidase present in the seminal fluid. Johnston and associates
(75) found the concentration of hyaluronidase increased at a
slower rate when the semen was stored at 5'0. than under stor-
age at 37'0. The concentration of hyaluronidase in spermatic
fluid is in direct proportion to the number of spermatozoa
found in the particular specimen as reported by Greenburg and
Gergill (60).

Kurzrok (82) and Johnston and associates (75) have re-
ported a lack of correlation between hyaluronidase titre and
one or more of the following: morphology, motility, concen-
tration, total sperm and volume. Johnston et a1. (75) have

reported significant negative correlation between hyaluronidase

21

content, the initial percentage of live sperm and the per-
centage of live sperm surviving cold shock.

Sallman and Berkeland (124) were the first workers to
study the relation of hyaluronidase to bull fertility. The
percent of fertile services increased with increasing amounts
of hyaluronidase up to a certain point beyond which fertility
decreased. From these findings, the authors suggest that in
some cases marked by oligospermia the addition of hyaluroni-
dase might increase the conception rate. On the other hand,
the fertilizing capacity of some semen, in which the hyalur-
onidase titre is high, might be improved by removing some of
the hyaluronidase. '

Tobin and associates (l#2) have reported that the hyalur-
onidase activity of testicular homogenate is decreased in rats
by a protein deficient diet. Johnston and Mixner (76) secured
no statistical correlations between the hyaluronidase content
and fertility levels of semen from bulls of relatively high
fertility when the semen is diluted at a rate of 1:100 or less.

Presegvation of Semgn

Stggage of Semen

Many investigators working on artificial insemination
problems have shown that a satisfactory rate of conception can
be obtained when semen is stored for varying lengths of time.

Herman and Ragsdale (70) noted that one-third more ser-

vices per conception was required when fresh semen was used four

22

to five hours after collection than when used one to two hours
after collection. Using an egg-yolk phosphate buffer as a
diluter, Phillips (106) and Phillips and Lardy (107) noted that
diluted semen which had been stored for 100 hours at 10° C
maintained its fertilizing capacity.

Breeding results obtained from 13 artificial breeding as-
sociations receiving semen from the University of Nebraska
bull stud was analyzed by Schultze et al. (128) to determine
the effect of day to day storage on semen fertility. They
found that fertility declines an average of H.6l percentage
units with each day of storage up to four days. Other inves—
tigators, Anderson (13) and Willett and associates (154), have
reported that no significant decrease in fertility occurred in
semen stored up to four days when the semen was of good qual-
ity, properly diluted, and quickly cooled.

Patrick (102) found in his study of factors affecting
semen storage and handling, that the quality of the semen is
lowered slightly by shipment. This slight reduction in the
quality of semen was believed to result from the lack of a low
uniform temperature in transit.

Anderson (7) studied the keeping qualities of bull semen
by determining the amount of time required to collect semen,
length of time before dilution, and time required to cool the
semen. He compared the results by diluting immediately and
cooling as soon as possible after collection, diluting immed—
iately and delaying cooling for #5 minutes, and delaying dilut-

ing and cooling for 45 minutes after collection. The differences

23

found in motility ratings 72 hours after collection, in in-
cubation tests 72 hours after collection, and in methylene

blue reduction time 24 hours after collection, proved that

significant differencasexisted, and immediate dilution and

quick cooling was the best procedure.

Foote and Bratton (52) found that based on 60 to 90 days
non-returns from 8,518 first and second service cows, the fer-
tility level of semen cooled in extender was 59.3 percent and
that cooled without extender was 52.8. The difference between
treatments of 6.5 percentage units was highly significant sta-
tistically. Motility estimates made after 3, 2h, #8, 72 and
96 hours of storage indicated that the samples cooled without

extender had a definitely lower percentage of motile sperma-

tozoa.

Diluters__

Considerable difference of opinion exists as to the rela-
tive merits of the available diluents for bovine semen used in
artificial breeding. Since the development in this country of
the phosphate-egg—yolk diluents by Phillips (106) and Phillips
and Lardy (107) and the citrate-yolk formula by Salisbury et al.
(120) various diluents have been used to preserve the semen of
the dairy bull.

Phillips and Lardy (107) found that egg-yolk buffered
with monobasic potassium phosphate and dibasic sodium phosphate
to a pH of 6.75 preserved motility of dairy bull semen for

24

periods in excess of 100 hours stored at 100 0. Salisbury
and associates (120) observed that an M/7.5 solution of
sodium citrate dihydrate mixed in equal amounts with fresh
egg—yolk produced a diluent which was superior to the yolk—
phosphate diluent for the preservation of motility when semen
was stored for six days or more. Later work by this author
and associates (121) showed that 2.9 percent of the sodium
citrate dihydrate per 100 ml. of distilled water gave an iso-
tonic diluter.

By means of a 6 x 6 latin square design, Bratton and co-
workers (33) compared six bovine semen diluents. Based on the
percent non—returns, the mean fertility level for each diluent
was as follows: phosphate-yolk, 50.5; 3.6 percent citrate-
yolk, 50.5; 3.6 percent citrate—sulfanilamide-yolk, 55.3; 2.9
percent citrate-sulfanilamide-yolk, 56.5; ortho tablet—yolk,
56.n; and ortho liquid, 55.0. The average non-returns for the
sulfanilamide-containing diluents was 5 percentage units higher
than for those diluents not containing sulfanilamides. This
difference was significant at the one percent level of proba—
bility.

Gravers and associates (58) found that the following
treatments of fresh semen had no significant effect upon con-
ception rate: (1) no treatment (control), (2) diluted with
fresh egg-yolk buffer, (3) diluted with stored egg-yolk buffer,
and (n) diluted with autoclaved milk.

Teeth and Herman (151) found that a synthetic pabulum

(Phillips) maintained a grade one motility in dairy bull semen

25

significantly longer than did egg-yolk citrate diluent, how-
ever, conception rate in the field with pabulum was signifi-
cantly less. Bayley and co-workers (20) furthered the work

of Teeth and Herman (151) by studying a synthetic pabulum vs.
yolk-citrate buffer as diluter of bull semen. In a trial in-
volving 1,2sn field inseminations, the fertility was 15 per-
cent higher with semen of 19 bulls diluted with egg-yolk cit-
rate buffer than with other portions of the same semen diluted

with a synthetic pabulum.

Anti-Bigtics

Practically all workers in the rapidly expanding field of
artificial insemination have stressed the bacteriological con-
trol of semen. Gunsalus et a1. (63) first discussed the un-
desirable effect of large numbers of certain bacteria in semen.
They collected #3 ejaculates from 19 bulls using an artificial
vagina. The bacterial count of these ejaculates ranged from
1,000 to 22,000 per cc. Gunsalus and associates (62) observed
that when sanitary precautions were practiced, the number of
bacteria found in freshly drawn semen or freshly prepared yolk-
citrate diluent was not sufficient to interfere with the methy-
lene blue reduction test for semen quality.

In a study of the genital tract of bulls inspected shortly
after slaughter, Gilman (56) reported finding Pseudomonas pyro-
cyaneus along with unidentified rods, micrococci, streptococci

and coliform organisms. In reproductive tracts of normal bulls,

his findings on bacterial content agreed with those of Williams

26

and Kingsbury (155) as to normal bulls being relatively free
of bacteria, whereas impotent bulls harbor large numbers of
bacteria. These authors reported finding micrococci, hemoly-
tic and non-hemolytic streptococci, coliform and Brucella
abortus in semen recovered from the vagina of cows immediately

3

after service.

Gunsalus et a1. (63) recorded plate counts of semen from
bulls with unclean sheaths from 10 to 100 fold higher than
those which previously had been cleaned. They found pseudo-
monas, coliform, diptheroids, bacilli, staphylococci and, in
one case, hemolytic diptheroids present in the semen. A high
percentage of the bulls diminished in fertility within six
months after the isolation of Pseudomonas pyocyaneus from the
semen. Edmondson and co-workers (46) have furthered the work
of the above workers. They isolated the following organisms,
listed in order of their predominance, from the semen of 36
dairy bulls used in artificial breeding work: bacilli, micro-
cocci, coliform, hemolytic, streptococci, non-hemolytic strep—
tococci, pseudomonas, actinomyces, proteus and yeasts. Five
sires from which Pseudomonas pyocyaneus organisms were isolated
were low in fertility, and eventually, all five became sterile.
There was no apparent relationship between the fertility of the
sires, livability of spermatozoa, and the total plate count of
the semen. These workers observed that the addition of micro-
cocci, yeast and non-hemolytic streptococci to fresh diluted

semen caused a substantial increase in the storage time.

 

 

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The control of certain bacteria by use of the bacterio-
static compounds is advocated and recormended by many inves-
tigators in the artificial insemination of dairy cattle.
Shettles (131) observed that the survival and activity of
human spermatozoa was not reduced by the addition of sulfa-
pyridine or sulfanilamide in concentrations up to and includ-
ing 160 mg. per 100 ml. of diluent.

Knodt and Salisbury (81), working at the Cornell station,
were the first investigators to study the feasibility of using
certain bacteriostatic compounds to control bacterial growth
in bull semen. They found that the addition of 200 mg. or more
sulfanilamide per 100 ml. of yolk-citrate diluter controlled
the growth of bacteria in stored diluted semen for 20 days at
5° 0. Later, these workers (122) observed that the use of 300
mg. of sulfanilamide per 100 m1. of diluter increased the fer-
tility of bull semen used routinely in the breeding of dairy
cattle.

The effects of penicillin added to bull semen were first
reported by Almquist and co-workers (6). They found no sig—
nificant decrease in the motility of diluted stored semen when
concentrations of penicillin ranging from 0 to 1,000 units per
ml. were added. However, levels of penicillin ranging from
1,000 to 2,000 units per ml. brought about a significant de-
crease in the motility during storage. Phillips and Spitzer
(108) recommended that .03 percent sulfathalidine, sulfasuxi—
dine or streptomycin be added to their L.G.B. (lipid, glucose,

buffergum) diluter for the control of bacterial contamination.

28

They also mentioned that penicillin, used in proper amounts,
was not toxic to the sperm. Later work by Almquist and
associates (5) demonstrated that streptomycin will inhibit the
growth of bacteria in diluted bull semen. The additions of
100, 250, 500, 750 and 1,000 gamma per m1. of diluted semen
did not significantly affect the livability of bull spermato-
zoa during a 20-day storage period, but levels of 1,250, 1,500
and 2,000 gamma per ml. of diluted semen brought about a sig—
nificant decrease in spermatozoan livability during a storage
period of 20 days. Easterbrooks and co-workers (44) studied
the effect of streptomycin upon the fertility of 16 dairy
bulls. They found that the addition of streptomycin to di-
luted semen increased the percent non-returns of 14 of the 16
bulls. This increase in percent of non-returns was 1%.” units
over the untreated semen.

Foote and Salisbury (54) studied the effects of several
sulfonamides upon the livability of spermatozoa and upon the
control of bacteria in diluted bull semen. Twelve sulfona-
mides were added to bull semen diluted with citrate-phosphate
and stored at 20'C. When the optimum level for each sulfa
drug was determined for spermatozoan survival, nine of the 12
compounds increased the livability of the spermatozoa over
that observed when no sulfonamide was added to the diluent.

Of these nine drugs that increased livability of the spermato-
zoa, only two sulfonamides, sodium sulfamethazine and car-
boxysulfathiazole were significantly superior to sulfanilamide

in maintaining motility of the sperm cells; they were inferior

29

in controlling bacterial growth. Sulfanilamide slightly de-
creased the rate of motility, and N-benzoylsulfanilamide ex-
erted a similar but more pronounced effect.

Foote and Salisbury (53),in studying the effects of a
number of compounds, chemically unrelated to the sulfonamides,
found that these effectively controlled bacterial growth.
Furacin and phenoxethal proved to be highly bactericidal and
at the same time were spermicidal at most of the levels tested.
Pyridium was limited to its usefulness by its low solubility.
Two 00mmercia1 penicillins were equally effective in controll-
ing bacterial growth and were slightly superior to sulfanila~
mide in this respect.

Various workers, Almquist and associates (4) and Mixner
(98), have studied the effect of a combination of penicillin
and streptomycin upon the livability and bacterial content of
bovine semen. Almquist et al. found that a combination of
penicillin and streptomycin in levels ranging from 100 to
1,000 units of each per ml. of diluted semen did not signifi-
cantly decrease the livability of bull spermatozoa during a
20-day storage period. The latter authors conducted two ex-
periments. The first experiment was run on a split sample in-
volving a total of 13 bulls of two breeds, 51 semen samples,
and 2,389 first and second services. The second eXperiment
was a two treatment reversal trial with forced collection
periods involving a total of 12 bulls, 48 semen samples and 801
first and second service breedings. For experiment one, the

control fertility level was 64.8 percent while that of the

30

treated was 64.7 percent based on 60—90 day non-returns.
For experiment two, the corresponding fertility levels were
68.4 percent and 70.4 percent. An analysis of variance in-
dicated that there were no significant differences in these
contrasted mean fertility levels.

Almquist (2) compared the effects of penicillin, strep-
tomycin,and sulfanilamide upon the fertility of dairy bulls.
He found that treatment of yolk-citrate diluted semen with
1,000 units penicillin per m1., 1,000 units of streptomycin,
1,000 units of each penicillin and streptomycin, and 300 mg.
percent of sulfanilamide increased the fertility 21.7 percent-
age units by penicillin, 25.9 percentage units by strepto-
mycin, and 21.3 percentage units by streptomycin plus peni-
cillin. Sulfanilamide gave a slight decrease of 2.9 percent-
age units.‘ Further studies by Almquist (3) showed that the
addition of penicillin to semen of certain bulls of lowered
fertility had a more beneficial effect while failing to be of
significant value when added to the semen of other bulls.
Mixner (99) substantiated the work of Almquist's by showing
there were no significant differences in fertility levels of
relatively high fertile bulls when 1,000 units of penicillin,
3 mg. of sulfanilamide, and 1,000 units of penicillin plus
3 mg. of sulfanilamide were added per m1. of diluter.

Myers and associates (100) and Sykes and Mixner (139)
studied the influence of aureomycin upon the livability and
bacterial content of bull semen. These authors found that the

anti-bacterial activity of 1,000 ug. of aureomycin per ml.

31

compared favorably with the combination of 1,000 units each

of penicillin and streptomycin per ml. of diluted semen.
However, the addition of aureomycin ranging from 50 to 1,000
ug. per ml. of diluted semen caused toxic effects on

motility when compared with portions of the same semen samples
containing no aureomycin or 1,000 units each per m1. of peni-
cillin and streptomycin. The latter workers also studied the
toxicity of chloromycetin upon bull semen. It was noted that
chloromycetin had a relatively low level of toxicity as the

initial toxic levels seemed to be between one and two mg. per

ml. of diluted semen.

Factors Affectinglguality of Semgp

ggason and Temperature

The well established fact that there is a seasonal ef-
fect on reproduction of domesticated animals suggests that
climatic factors such as light and temperature may be respons-
ible.

A number of workers have studied seasonal variation in
semen quality and fertility of dairy bulls. Miller and Graves
(97) observed that the Beltsville herd required more services
per conception in July, August and September than during the
rest of the year. Dawson (42) studying the fertility of aged
bulls, used at various locations in the United States, found

that the relative fertility of sires used at Southern stations

32

was 36 percent as compared to 49 percent for sires used at
Northern and Western stations. He concluded that the lesser
variation in length of daylight may account for the rela-
tively good winter results reported at low latitudes.

A study by Erb and associates (51) of the breeding effic-
iency in the Purdue University dairy herd for a 20 year period
revealed considerable seasonal variations. The month of May
with 74.3 percent had the highest average efficiency, and the
month of August with 58.2 percent the lowest average effic-
iency for the year. Seath and Staples (130) studied an 11 year
history of the North Louisiana State EXperimental Herd and the
Louisiana State University Herd. Seasonal differences in rate
of conception were found in both herds. In each case the
summer months required more services per conception. The best
rate of conception in the Experimental herd was during the win-
ter months followed by the fall period. The University herd
had a reverse in this order with the fall months first and the
winter months second.

Semen quality examinations by Erb and associates (48)
showed it to be of superior quality in the spring and low in
quality during the summer; The average semen volume and in—
itial motility was least in July, August and September. The
length of sperm survival was least in August and lower in
July, September and November than during the other months.
July, August and September were also months of high percent-
age of abnormal spermatozoa. Spermatozoa concentration and

total spermatozoa per ejaculate were at high levels during

33

April, hay and June.

Observations were made by Phillips and co-workers (103)
on volume, motility, number of spermatozoa per 0. 0., total
abnormal spermatozoa, and proportions of abnormal heads,
necks, middle pieces and tails of semen collected from beef
and milking shorthorn bulls. Significant or highly signifi-
cant seasonal differences were found in volume, concentration,
total Sperm, and proportions of abnormal heads, necks, middle
pieces and tails. Of 1,135 matings, 59.6 percent resulted in
infertile matings in April and 40.8 percent in August.

Swanson and Herman (136) studied monthly variations in
motility, volume, concentration, livability in storage, pH and
morphology of semen from bulls used in the University of
Missouri dairy herd. The pH cf the semen was significantly
lower in the summer than in the fall. Initial motility and
viability in storage were lowest in the winter.

An analysis of 51,587 breeding months in the Cornell
University herd by Clapp (38) showed an average of 2.11 ser-
vices per conception.‘ There appeared to be a trend toward
greater efficiency from March through July. Breeding effic-
iency dropped sharply in August and continued at low level
through February; July required 1.90 services per conception
and February 2.29 services per conception.

Mercier and Salisbury (96) found that the lowest percent
of successful services was obtained during the winter and
spring and the highest during the summer and fall. The differ-

ence in fertility level between herds was not significant

34

statistically, but those between seasons were significant at
the five percent level of probability. The average monthly
conception rate of the three herds studied in Eastern Canada
was significantly correlated with the monthly average length
of daylight. Temperature changes had no measurable effect on
fertility level.

Lewis (88) found that monthly variation in semen quality
was not significant in the dairy bull, but the quality was
higher in the spring and summer than during the fall and
winter. Light and temperature were both positively correlated
with spermatogenesis. Light appeared to exert the greater
effect.

A study of the seasonal effects showed a highly signifi-
cant decrease in percentage of motile spermatozoa during the
early spring months and a highly significant difference be-
tween months in spermatozoa counts, Salisbury (119). The low-
est average counts was found in August, but there was no sig-
nificant difference in fertility of the bulls from month to
month.

An analysis of the breeding records at the Bureau of Dairy
Industry, Hilder and associates (71) showed that a relatively
large number of services were required for conception during
midsummer followed by a sharp decrease in the fall.

kercier and Salisbury (95) investigated on the seasonal
variations in fertility of about 25,000 cows and 71 bulls of
Various ages bred artificially in New York. Winter was found

to'be~the poorest breeding season of the year. The fertility

35

level of the bulls was found to be significantly correlated
with the length of daylight, there being a lag of one or two
months before the effect of daylight reached its maximum.
They concluded that young bulls probably are more subject to
changes in light and temperature than are those bulls from
six to ten years of age.

Table II shows the seasonal variation found by the authors
reviewed in the foregoing as well as data concerning other

species. Table III presents a summary of the seasonal effects

upon the characteristics of semen.

Age and Frequency of Ejaculation

A difference in breeding efficiency between young and old
bulls was found by Miller and Graves (97) in a study of the
Beltsville herd. Young bulls appeared to be more fertile than
mature bulls when bred to fertile cows. Tanabe and Salisbury
(140) found that bulls between the ages of one to three years
inclusive, had the highest breeding efficiency of all age
groups.

An analysis of 2,636 dairy bulls by Winters (157) indi-
cated their average useful age to be 10.63 years. Sixty-one
percent of the 2,636 bulls were in active service when they
reached 10 years old, and 4.3 percent of the bulls were still
fertile at 15 years of age. Baker and Queensberry (18) were
unable to find any fertility differences between old and young

range beef bulls. Since the older bulls had been selected for

EASONAL VARIATION

 

 

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TABLE II

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High Low
Author Species Fertility Fertility
Parker (101) Fowl Spring Fall
Late Spring
Asdell (17) Cost Fall Early Summer_
Turner (145) Goat Fall Spring-Surmer
Eissonnette (24) Goat Fall Spring-Summer_
Green (59) Ram Late Fall Summer
NeKens£p (92) Ram Fall Summer
Yeates (159) Ram Late Fall Summer—Early Fall
Miller (97)_ Bull _fi Summer
Late Winter
Qawson (42) Bull Early Spring
Erb (51) Bull May August
Seath (132) Bull Fali—Wgnter SpringrSummer
Phillips (10;) Bull Aergg August
anpp (38) Bull Spring) Late S wmer—Fall
Mercier (95) Bull Summer—Fall Winter-Spring_
Lewis (83) Bull Spring—Fall Fall-Winter
Late Winter

ggider (71) Bull - Summer

 

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38

high fertility, it is likely that any differences were ob-
scured. Werner and associates (152) and Dawson (42) showed
that young bulls showed the highest level of conceptions in
natural breeding.

Bowling and associates (28),in studying breeding records
over a period of 18 years found that bulls 13 years of age or
over were significantly less sure breeders than bulls of six
years of age. The breeding efficiency of bulls as they in-
creased in age did not become significant until the bulls
reached an average age of six years. Hilder and co-wcrkers
(71) using data from 8,919 natural services reported that the
number of services per conception for bulls of all ages was
2.67. Bulls seven to 10 years of age required 3.14 services
per conception, while bulls under five years of age 1.52 ser—
vices per conception.

An age difference in response to seasonal variation in
fertility was observed by Mercier and Salisbury (95). The cor-
relation between fertility level and average length of daylight
for the same period was not significant for bulls under six
years of age. These young bulls were relatively high in fer-
tility in winter, gradually decreasing to a low in the hot
temperatures of summer. The relationship was high for bulls
0f SiX’tO eight and eight to 10 years of age, low for bulls
over 10 years of age, and high for all bulls.

fieatherby et al. (149) showed a marked decrease in sperma-
tozoan concentration of the semen of the bull used once each

day fer a 57 day period. Lasley and Bogart (86) have reported

39

that semen volume, total number of spermatozoa per ejaculate,
percentage of morphologically abnormal spermatozoa, and fer-
tility increased in range bulls as the interval between ejacup
lations increased from one up to 10 days. While statistically
significant, the correlation coefficients which they obtained
were quite small. Mercier and associates (93), working at the
Cornell Station, concluded that a six day interval between
ejaculations is not detrimental to spermatogenic activity.
Three groups of four bulls each were ejaculated according to
the following schedule during a period of 216 consecutive days;
one ejaculate every six days; two ejaculates taken within a

few minutes of each other at 12 day intervals; and three ejacu-
lates taken within a few minutes of each other at 18 day inter—
vals. The volume of semen per ejaculate average 7.9, 6.6, and

5.3 ml. for the six, 12 and 18 day intervals respectively.

Libido

The problem of improving the libido of bulls is rarely
mentioned in the studies of sterility in the male bovine.

McKenzie and Berliner (92) reported that libido is relap
tively independent of spermatogenesis in the ram. They found
that sterile rams might exhibit normal sex drive and fecund
rams might show very little. Hart and associates (67) noted
that semen quality for artificial insemination from three
bulls was reduced due to a lack of sexual drive. Hellstrom

(68) found that in five cases when bulls were allowed to serve

40

immediately, no semen was ejaculated,and in 12 others only
1—3 ml. (average 1.7) was produced. When the bulls were re-
strained for 1—6 minutes, the semen volume was increased to
4.9 m1. and after a longer wait the volume increased to 5.3

ml.

The Role of the Endocrine System in Fertility

gpdocgine lnteractio s

Knowledge of the interactions of the hormones ffecting
sexual activity is meager. The internal rhythm of reproduc-
tion in our higher animals is brought into relation with
seasonal changes and other external environmental phenomena.

In particular, there is new general agreement as to the dom-
inating role played by the anterior pituitary gland, which

is recognized as being the organ directly stimulated, while
activation of the gonads is brought about indirectly through
the pituitary. The thyroid gland also exerts an effect upon
the gonads through its effect on cell metabolism. The anter-
ior pituitary gland secretes a thyrotrophic hormone which regu-
lates the amount of thyroxine secreted by the thyroid gland.
Thyroxine, in turn, depresses the rate of secretion of the thy—
rotrophic hormone by the anterior pituitary. Gonadotrophic
hormones from the anterior pituitary affects the activity of
the gonads. In turn, the gonads secrete hormones which depress

the rate of secretion of gonadotrophic hormones from the anterior

41

pituitary gland. It is logical to expect, therefore, that
these changes may condition the metabolic processes, but in
part, at any rate, act exteroceptively through the nervous
system and probably through the hypothalamus upon the anterior

pituitary and then upon the testes and ovaries, Turner (144).

Effect of the Anterior Pituitary

It appears that the most widely supported and likely
mechanism of pituitary stimulation by light is that involving
the eye as a receptor. The transmission of impulses or
stimuli to the pituitary is affected through a neural pathway
as well as possible by humeral means.

A good deal of work has been done on the use of various
hormones upon sterility and sexual inactivity in dairy bulls,
but very little data on this condition has been reported in
the literature. The interest of research workers in Dairy
Husbandry is doubtless centered on the possible use of the
gonad-stimulating hormones as having influence in correcting
breeding troubles in the dairy bull. Those breeding diffi—
culties in which infection is not the primary cause and in
which abnormal testicular function impairs fertility would ap—
pear to offer some possibility of responding to treatment with
spermatogenic stimulating hormones.

Although the chorionic gonadotrophin is assumed generally
to activate chiefly the interstitial cells of the testes,

favorable reports concerning its therapeutic employment in di-

verse grades of seminal failure have been shown. Pighine (109)

42

treated eight sterile bulls with anterior pituitary tissue

and six became active again. The treatment of three bulls
which produced semen with low sperm motility with chorionic
gonadotrophin improved the quality of the sperm as reported
by Bottomley and associates (27). Though the existence of
seminal failure due to inadequate gonadotrophic activation
from the pituitary has been presumed from both the experimen-
tal and clinical observations, factual proof that pituitary
deficiency may induce seminal failure without androgenic fail-
ure is lacking.

The andr0gen content of the testes increases at a uniform
rate during the first two years of life, from two to five
years it increases sharply, and thence forward it decreases.
This may be one of the many reasons why young sires require
fewer breeding services per conception, There are no striking
changes in Leydig cells or in the androgen content of the
testes at puberty as reported by Asdell (15). Bottomley et a1.
(27) reported injection of 2 cc. of human pregnancy urine ex-
tract. The results of these experiments indicate that chori-
onic gonadotrophin may be of great value in treating sterility
in the bull when endocrine deficiencies are suspected.

Erb and Andrews (49) noted that the injection of 2,250 R.
U. of gonadotrophin into a dairy bull caused a decrease in ven-
ous blood plasma ascorbic acid of 42 to 67 percent during the
first 24 hours. The recovery of ascorbic acid to approximate
per injection levels required longer than eight to 10 days.

Durrell (43) treated four bulls, with low ability to mount,

43

with 300 mg. of testosterone propionate. A11 of the bulls
responded favorably, but in one, the increased response was
only temporary. Hart (66) reported that a valuable Hereford
sire injured his penis in service and would not make any
effort to breed. One year after the injury, 1,500 I.U. of
gonadotrophin in pregnant mares' serum were injected. This
stimulation brought about by the injection of the pregnant
mares' serum overcame the inhibition, and in two days he bred
a cow normally.

The injection of large quantities of sheep pituitary ex-
tract and of pregnant mares' serum into bull calves one to
four months of age, by Casida (35), did not produce any mature
sperm. The size of the testicles was increased, but it was
not definitely determined whether this was due to increased
interstitial tissue or size of seminiferous tubules. The sem-
inal vesicles of these calves were definitely stimulated which
indicated an increased activity of the interstitial cells. In
no case was there definite evidence of development of sexual
desire even with extreme development of the gonads. Asdell
and associates (16), however, were unable to note any results
from administering gonadotrophic hormones to sterile cows.

The latter workers caution that the high rate of spontaneous

recoverings often encountered render it difficult to give cor-

rect interpretation to findings.

44

Effect of the Thyroid Glagg:

A good deal of work has been done on the use of various
hormones upon sterility and sexual inactivity in males, but
judging from the literature on this work with various species
most of the work with our domestic animals has been with thy-
roxine. This hormone, secreted by the thyroid gland, controls
the basal metabolism and this is essential for the efficient
function of every cell of the body. There is evidence avail-
able that hypothyroidism often is associated with infertility,
so this hormone must be considered in any accyunt of hormonal
therapy for spermatogenesis.

When there are lowered basal metabolic levels, thyroid
substances often prove to be effective in therapy of seminal
failure. An extensive review of the physiology of thyro-active
substances has been made by Reineke (115). Out of a total of
14 bulls that received thyro-protein treatment by Reineke (114),
10 were observed to show definite improvement in vigor and
libido. There was no change in the other four bulls receiving
the thyro—protein treatment. The time noted for an observable
effect to occur averaged 16 days. Definite evidence of improve-
ment in the conception rate was inadequate, but the limited
records were suggestive of an improvement in spermatogenesis.
Definite improvement of libido of bulls with some indications
of improved fertility were observed on a dosage of approximately

0.5 to 1.0 gram of thyrc-protein daily per 100 lbs. of body

weight 0

45

Schultze and Davis (129) fedl.0 to 1.24 gms. of thyro-
protein per hundred pounds body weight daily to seven bulls
for 30 days. Initial motility of the group showed definite
improvement. The percent of abnormal spermatozoa changed
little except in one bull where it decreased markedly. Con—
ception rates of five of the bulls increased from an average
of 51.7 percent to 55.0 percent within the first 10 days.
After 10 days, the conception rate increased to 58.6 percent,
and during the 10 days after feeding stopped, the conception
rate further increased to 60.4 percent. Seven other bulls,
used as controls, exhibited no changes in breeding efficiency
during this time.

Spielman and associates (133) reported that a thyroidecto—
mized bull produced visible spermatozoa, but libido was com-
pletely absent. The administration of thyroid, dinitrophenol,
and testosterone propionate temporarily restored normal breed-
ing behavior.

Eaton and associates (45) observed the effects of feeding
thyroprotein on semen characteristics of rams. Comparison was
made between groups of rams fed 2 gm., 1 gm. and no thyropro-
tein. These results indicated that the feeding of thyropro-
tein to rams was not beneficial since neither fed group was as
good as the unfed group in spermatozoa concentration, percent-

age of normal sperm, and motility score. However, the volume
of the ejaculate was somewhat higher in the lot fed 2 gms. of
thyroprotein in the daily ration for a period of 15 weeks.

Bogart and Mayer (25) showed that thyroxine or thyroid active

11

o

b
V O
p a -
\
. '1

O
D
O

46

protein, administered orally by injection, alleviated symp-
toms of summer sterility in rams resulting from impaired
spermatogenic activity.

Warwick and co-workers (14%) substantiated the work of
Eaton and associates (45) by showing that treatment of rams
with thyro—protein in the months of April and May had an
apparent deleterious effect on semen quality as measured by
initial fertility, livability, density, and ability to re-
duce a solution of methylene blue. These workers also fur—
thered the work of Bogart and Mayer by presenting data to
show that treatment of rams with thyroprotein during the sum-
mer months produced semen which was either equal or slightly
above the semen produced by the controlled group.

Martinez (89) reported that thyroprotein fed as 0.04
percent of the ration caused a definite stimulation of
spermatogenesis in the domestic fowl. Jaap (74) noted that
doses of 0.25 to 1.0 gms. of desiccated thyroid gave an in-
crease in the size of the testes of drakes during late win-

ter and early spring months.

fipgrigional Factors

Vitamin A

The importance of vitamin A in developing and maintain-
ing the normal germinal epithelium, and the breeding ability

of young bulls has been amply demonstrated by Sutton et al.(134)

47

Hodgson et a1. (72) and Erb et a1. (50).

Phillips (150) reported that cellular sloughing is noted
in vitamin A deficiency, but spermatogenesis continues. The
condition could also be repaired after 60 to 90 days of vita-
min A. administration.

Sutton et al. (134) noted the following changes in the
young male bovine from a ration low in vitamin A: degeneration
of the germinal epithelium of the testes, absence of spermato-
zoa in the epididymis, and an accumulation of fluid in the
cleft between the anterior and posterior lobes of the pitui-
tary gland. Regeneration of the germinal epithelium following
vitamin A and carotene therapy has been observed by Hodgson
and associates (72) and Erb et a1. (50). These latter workers
reported that a bull fed a low vitamin A ration for four
months became blind, had staggers, and gastric intestinal dis-
turbances. By using testicular biopsy, they found severe de-
generation of the seminiferous tubules and nearly complete dis-
appearance of sperm from the lumen of the tubules. Feeding of
60,000 to 150,000 units of vitamin A per day resulted in re-
covery within two to five months.

Six dairy bulls were fed dry roughages low in carotene and
a concentrate deficient in Carotene and vitamin A for a period
0f 16 months by Bratton and associates (34) without inducing
clinical manifestations of the deficiency. when the roughage
compmnent of the ration was changed from hay and/or straw to
driedbeet pulp, development of incoordination, edema of the

exhrendties and papillary hemorrhage resulted. They also noticed

43

a decrease in the percent of motile spermatozoa and a gradual

increase in the percent of abnormal apermatozoa.

1Jri t 3min C I

Phillips and associates (105) reported that bulls having
a low ascorbic acid value for semen (two mg. or less) were
brought back to normalcy in a large majority of cases within
five weeks by the subcutaneous injection of Vitamin 0.

Phillips also pointed out that semen ascorbic acid values
above eight mg. percent were toxic and the quality of the semen
may be as poor as when ascorbic acid values are low.

The mechanism of how vitamin C improves spermatogenesis
is not definitely known. Berg and co-workers (21) found that
the ascorbic acid is concentrated in the seminal vesicle.

These authors assume that the spermatozoa are kept viable after
spermatogenesis is completed by the ascorbic acid in the semin—
al vesicles until they are ejaculated.

Phillips and co-workers (105) showed that blood plasma
ascorbic acid declines with the development of vitamin A defic—
iency. Twenty cc. of cod liver oil per day was required to
maintain portal ascorbic acid values in Guernsey bulls. That
there is a difference between breeds,with the Holsteins lower
than the Guernseys, has been reported by Phillips and associ-
ates (104).

Bortree et a1. (26) showed that the feeding of chlorobu—
tanol to cattle resulted in a marked increase in plasma ascor-

bic acid. Recent work has shown that the feeding of chlorobu—

”9

tanol to the bovine results in a marked increase in the level
of ascorbic acid in the blood plasma. Fifteen slow breeding
bulls were fed chlorobutanol orally by Soheidenhelm (126).

The libido of the bulls improved in 76.6 percent of the cases.
The average time reouired to serve a cow was reduced from #5
minuted to 3.7 minutes. Only two sires were able to Withstand
doses of 20 grams of chlorobutanol per day for more than a

three week period without developing muscular incoordination.

Vitamin E

Somewhat contradictory claims are presented in the liter-
ature in regard to the value of vitamin E for normal reproduc—
tion of dairy cattle.

That vitamin E has no value in improving spermatogenesis
in the dairy bull, has been shown by Gullickson and co-workers
(61). These workers fed seven bulls on a ration devoid of
vitamin E and found that growth, physical, and sexual develop-
ment were normal in every respect. The feeding of one ounce
daily of solvent, process wheat germ oil, in addition to the
normal ration, by Salisbury (119), did not increase the volume,
concentration, motility, or shorten the time required for ser—
vice.

On the contrary, Timin and Perelurian (141) reported de-
cidedly favorable results from the feeding of vitamin E in the
form of wheat germ concentrate. A comparison between the bulls
fed the concentrate and those used as controls showed a 31.5

percent increase in volume, 63.0 percent increase in Sperm

50

viability, and a 32 percent increase in sperm concentration
in favor of the wheat germ concentrate. These beneficial
effects were noted 25 to 30 days after feeding started. They
recommend 800 to 1,000 gms. per bull per day.

Kafka (79), studying the case history of 126 non—breed-
ing cows, found that treatment with wheat germ oil gave 65
percent positive conceptions, seven percent negative concep—
tions, and 28 percent non—conclusive results. Jones and
Ewalt (78) injected wheat germ oil in 49 females at the Oregon
State College Dairy Herd. The dosage varied from 10 cc. to
20 cc. per injection. Forty of the cows injected, calved,
three were disposed of as sterile, and no records were avail-
able for the remainder of the cows. They concluded that
vitamin E had a favorable influence in the case of 15, indef-

inite results in the case of 23, and negative results with

five females.

Amino Acids

The optimum amount of dietary protein that is needed for
producing high quality semen in the dairy bull has been under
investigation for some time.

Holt and co-workers (73) working with humans found that
a diet deficient in arginine over a ten day period caused a
reduction in the number of spermatozoa to one—tenth of the

normal values. They concluded that atrophy of the spermato-

genic tissue took place. Guterman (64) studied five men pa—

tients before, during and after amino—acid therapy. One

51

month prior to the amino acid therapy the average sperm count
was 11.2 million per cc.; after eight months of treatment, the
average concentration had increased to 47.0 million per cc.
The amino-acids were then discontinued, and eight months later
the sperm averaged 21.8 million per cc. This worker also
treated 13 infertile men with oligospermia in which they re—
ceived 1.8 - 2.7 grams of arginine and minimal amounts of
lysine, tryptophane, and pyridoxine in tablet form for eight
months. The tendency for sperm concentration to increase was
as great in the untreated group as in the treated groups.. It
appears that amino-acid therapy for oligospermia should be
reserved for those patients who exhibit or give the history

of inadequate protein in-take. Berg and Rohse (22) found

that a period of uncomplicated trytophane deficiency in young
male rats, lasting as long as 20 days, does not induce subse—
quent sterility.

Jones and associates (77) using two groups of bull calves,
starting at five to seven months of age and continuing to 32
to 41 months of age, compared the effect of two supplemented
alfalfa hay rations upon fertility. The basal ration consis-
ted of alfalfa hay, disodium phosphate, salt, and potassium
iodide and the supplemented basal ration consisted of the
basal ration plus one pound each of skim milk powder and cat
groats. Bulls fed the basal ration produced good quality
semen after 18 months of age and were fertile on service be—
tween two and 3.5 years of age. Bulls fed the supplemented

basal ration produced good quality semen after 12 months of age,

52

and were fertile on service. The average initial motility
was rated 52 percent of the samples on the basal ration as
compared with 72 percent of the samples on the supplemented
basal ration. The authors believed that the earlier maturity
and better condition of the bulls fed the supplement was due
to the greater energy intake.

Brenton and co-workers (30) studied th measurable semen
characteristics and relative fertility of 18 bulls when they
were fed the protein supplement and timothy hay es the only
roughage. Based on 60 to 90—day non-returns to first service
cows, the average fertility levels of the semen produced when
the bulls were fed corn gluten feed, skim milk powder, and
soybean oil meal were 63.5, 61.6 and 65.7 percent respectively.
The results showed that corn gluten feed, skim milk and soy-
bean oil meal were approximately eoual in value as protein
supplements in the concentrate mixture. It is doubtful whether
any real advantage lies with the soybean oil meal because the
difference is relatively small.

Reid and associates (112) indicated that the ingestion of
a simple and/or complex concentrate gave similar characterist—
ics of good quality semen. Eranton and co-workers (31) found
comparable results in semen characteristics, relative fertility
and body weight changes when the T. D. N. intake levels varied
from 100, 120 and 1&0 percent of reconnended maintenance re-
quirements for dry dairy cows of equivalent weights fed simul—
taneously with concentrate mixtures containing 12, 16 and 20

percent total protein.

hinerals

Lardy and associates (85) studied the effect of a low
manganese ration of corn, corn gluter, timothy hay, and min-
erals upon semen production. They found that ejaculates from
the three bulls reared on the low manganese diet produced a
small volume, low concentration, poor spermatozoa motility,
and a short storing period. In contrast, the ejaculates from
three bulls receiving the same ration plus a supplement of
manganese sulfate produced a normal volume, high concentra-
tion, excellent motility, and the spermatozoa maintained motil-
ity for a long storage period. These authors indicated that
an adequate amount of manganese is essential for sperm produc-
tion in the bull. Karked improvements in semen quality was
observed by Kncap (80) in seven of the 11 problem sires who
daily received 50 mg. potassium iodide plus .8 pound of skim
milk powder for a period of two to six months. Improved sperm-
atogenesis was indicated by one or all of the following fac—
tors: libido, Quantity of semen, output of sperm cells, per-
centafie of living sperm cells, and the motility activity rat-
ing of the cells.

Boyer and associates (29) found that a manganese defic-
iency in male rats did not result in lowered ascorbic acid
content of the various tissues. However, the rats on the def-

icient diet showed complete lack of spermatozoa.

54

SUMMARY OF THE REVIEW OF LITERATURE

The factor of exercise in management of dairy bulls
has not received adequate study. Various investigators
(19, 65, 87, 151 and 160) have indicated that exercise may
give favorable effects on fertility; however, the data pre—
sented is somewhat contradictory. Exercise may increase
semen quality and libido in the bull. If exercise affects
soermatogenesis in the dairy bull, the physiology involved
is not well defined.

Semen characteristics have been shown to be influenced
by various factors. That the seasonal variation affects
semen quality and fertility of bulls is evident (3a, 51, 96
103 and 130). Several investigators (42, 51, 88, 95, 96, 103
and 130) have demonstrated that fertility is affected by
season. These authors concluded that light and temoerature
were two of the factors involved. The quality of the semen
appears to be lower during the summer and fall months.

The age of the bull asbears to have an affect upon breed—
ing efficiency (28, 42, 71, 97, luO and 152). It appears that
bulls six years of age and younger produce higher quality of
semen than older bulls. That the frequency of ejaculation may
affect the breeding abilities and fertility of the bull has
been shown by (86, 93 and 149). From these data, it is reason-
able to conclude that a six—day interval between ejaculations
is not detrimental to spermatogenic activity.

The factors affecting libido in bulls is not definitely

55

known. Two workers (67 and 68) indicate that libido is rela-
tively dependent of spermatogenesis in the bull. The data
showing the effect of the ration on libido is contradictory.
Several workers (26, 105 and 126) showed that a ration which
improves vitamin 0 synthesis or the injection of ascorbic

acid will aid in maintaining sex drive. Improvements in semen
quality was obtained by manganese sulfate and potassium iodide
therapy as indicated by (80 and 85). The feeding of manganese
deficient diets to male rats by (29) resulted in sterility.
The eXperiment work conducted in the United States (61, 78 and
119) indicates that the feeding of wheat germ oil as a source
of vitamin E is of no value in maintaining semen quality. The
importance of vitamin A in developing and maintaining breeding
efficiency of young bulls has been demonstrated (34, 50, 72 and
134).

There is evidence in the data (114, 129 and 133) that thy-
roid substances often prove to be effective in therapy of semin-
al failure. Hypothyroidism is associated with impaired sex in—
terest. Gonad—stimulating hormones (27, 43, 66 and 109) may
have an influence in correcting breeding troubles.

Data on the relationship of semen quality to breeding ef-
ficiency have varied (20, 46, 94, 135 and 137). Investigations
(9, 41, 69 and 70) to date, indicate that initial motility of
the spermatozoa is the best laboratory measure of semen fertil-
ity.

Values (13, 51, 69 end 70) for good quality of semen varied

somewhat, but it appears that semen to be inseminated should

56

have the following characteristics: (1) normal volume -— 4
m1., (2) concentration -- 800,000 permatozoa per cu. mm.,

(3) motility rating -- 70 percent progressively motile sperma-
tozoa, (4) abnormal spermatozoa -— less than 30 percent, (5)
hydrogen-ion concentration —- 6.8.

Various authors (75, 76, 124 and 142) have studied the
relationship of hyaluronidase titre to fertility levels. No
conclusive evidence has been presented.

Many investigators have studied the storage of semen
(7, 13, 52, 70, 102, 106, 107, 128 and 154). Most workers
are of the opinion that a storage temperature of 5° C is opti-
mum, and that semen, if used for insemination, should not be
stored over four days. Various diluents (20, 33, 106, 107,
120, 121 and 151) have been used in the United States to pre—
serve semen. Best results in maintaining the fertility of
semen have been obtained with the buffered egg-yolk—citrate
and the buffered egg-yolk—phosphate diluents. Many workers
(5, 6, 54, 81, 98, 100, 108 and 139) have studied bacterio—
logical control of semen. A combination of penicillin and
streptomycin added to the above accepted diluents has more de—
sirable anti-biotic pronerties than any other bacteriostatic

compound.

57

OBJECT

The object of this experiment was to observe the effects
of forced exercise of dairy bulls upon their semen character—
istics (volume, concentration, motility and percent abno male),
and the fertilizing capacity of their seven by computing the
percentage non—returns on first and second service cows based
on 60—90 days. These cows were owned by patrons of the

Hichigan Artificial Breeders Cooperative Incorporated..

EXPERIIEITAL PROCEDURE

Selection of Animals

Thirty—two bulls of the hichigan Artificial Breeders Co-
operative Incorporatead varying from four to 15 years of age
were divided into eight groups according to breed and to high

or low fertility as shown by Table IV.

Feedinggand Hanagement

Approximately one-half of the bulls in this experiment
were housed in 9' by 11' box stalls and the other one-half in
5' by 8' tie stalls. All bulls received a 15 percent protien
concentrate, (Table V), and an average quality alfalfa—brome—
grass hay. In addition, grass silage was fed for the first
122 days, followed by corn silage for the last 59 days. The

analysis of the grass silage and corn silage is shown in Table VI.

flBER 30, 1949

‘\

FROM OCTOBER, igus THROUGH SEPTE-

A

 

 

TAB LE IV

 

 

SUIEMARY 0F BREEDING EFFICIENCY FOR THE INDIVIDUAL BULLS

 

58

 

 

 

 

 

 

 

 

 

 

 

I». to F
(DEC-1 O
03 N \O m .2." H N
C \O \0 L0 \0 m \0
P. H J N
+9 (D
«4 g o O\ O H N
H C 24' N M M M
H
H g .. C‘ .0 .. .fi .. .. .q .. .. .‘ .0 .. . .0 .. .O .. .. .0
U) (D O
In C 0
H HER. Ln N N :1- 3 N
B (D \0 Ln \0 \o \o
O O +3 N
.J 0)
a: H d
o d H N M :l'
H :r: 23 N N N N
N .. .. .d .. .I .. .. .4 .. .. .‘ .. .. .i .. .. .O .. .. .4 .. .. .J
H)
[11 >: o
are! H N L0 L0 M Ln
I b: m \o N \o \o \o \o
49 c: N
:2" OH H
H (D '
O H :3 0 Ln \0 I\- ‘60
4D (5 2; N N N N
2 H
(D .0 OJ OO OO OJ .0 CO .d O. OO OO O. O. O . .0 OO OJ OO OO O
[1. m
C O
,c: HE'S-1. LA '60 N d’ O\ N
L0 0) [~- \0 [- l~ no [-
-H +3 N
a: CO
H J
O O N ’60 Ch 0
C13 ’23 H H H N
00 00 0d 00 OO DJ 00 OJ OO OO O. OO O. OJ OO OO O. O. OO O . OO O. oi OO O. .1
m
>5 O
ms". 3 O N :J‘ N O
m m Lf\ Ln 0 Ln
G N
h H
+3 (D J
«4 :3 o M :1- Ln \0
S U 2 H H H H
P OO OJ OO OO OJ OOOO OJ OO OO OJ OOOOO OOOO OJ OO OOO
H M
Q) C‘. O
m It. n—na‘l no Ln \0 0 ON [\-
Q.) UN m KO m N m
U) B P N
O 03 J
H OJ H
O 0 LC\ \0 N w
0 :13 24
m .. .. .J .. .d .. .. .J .. .. .d .. .. .J .. .. O 1 .. .. .1 O. .. 0‘
L“
Ed >3 O
(DE-Q Ln N O :J- \O \o
N >0 (D \O \O \O I‘- \O \O
+9 c: N
[1] 0H H
H (D 1
«4 :3 o O\ O H N
+3: (5 :2: H H H
G) O. OJ OO OO OO OO OO OJ OO OO O. OO OO O OO OO OJ OO OO OJ
[Ia M
G O
.13 «4‘32 0\ '60 O :1- H 0
DD 0) \O \O I‘- l‘ $0 I‘-
0H +9 N
{I} a)
H J .p
O O H N M .21“ P
:n:: E4 ‘< |

 

 

% Non-returns: 60-90 days

 

31.. 04:

4.: 1’9! dQJIQIQ'IFuJ 3. _ ~

.1...

59

TABLE V
CONSTITUEETS OF GRAIN RATION

 

 

 

 

 

 

 

Feed Pounds
W
D. M. = 23.01b80
TOD. N- = 81.71b8.
Corn 300
Wheat bran 600
Wheat middlings 300
Meat scraps 200
Linseed Oil meal 100
Soybean oil meal 100

 

M. V. P. poultry con—

 

 

 

centrate 100
Salt 1.5%
Cobalt 3.0 oz.
Mn 8 04 1.0 lb.

 

Legend - I"According to the Morrison Standard

D. P. : Digestible protein
D. M. = Dry Matter
T. D. N. a Total Digestible nutrients

60

TABLE VI

ALALYSIS OF THE

CORN SILAGE AED GRASS SILAGE

mm

W

 

 

 

 

Protein Protein
Moisture Tet Basis Dry Basis
.o 0% 4%
I I I
Corn . 70.36 2.41 8.10
Grass 50.70 7.70 15.50

 

I*Association of

Official Agricultural Chemists

61

The average daily level of feeding the grain mixture, silage,
and hay was 3.5 lbs., 12 lbs., and 15 lbs. respectively.

This ration contained sufficient digestible nutrients to meet
the Morrison Standard.

The original plan called for weekly semen collection.
However, because of the fluctuations in demand of semen, con-
dition of the bull, and the management practices, this time
schedule could not be strictly followed. In general, the in-
terval between collections was longer depending on the indi-
vidual bull.

An artificial vagina was used for collection. In most
cases the bulls were ejaculated twice at each collection time
with a short interval between the first and second ejaculates.
In no case was a third collection made. For each ejaculation
the bulls were restrained depending upon their habits and

libido.

Exercising Procedure

During the first 35 days, one—half the bulls were exer-
cised for 15 minutes in the afternoon on a mechanical exer-
ciser with a speed Of 1.24 mi. per hr. The amount of daily
exercise was increased to 23 minutes at the same rate of speed
for the following 15 days. For the remaining 119 days of the
experiment, these bulls were exercised daily for 30 minutes at
the rate mentioned above on the mechanical exerciser. NO

bulls were exercised on Sunday.

62

Method of Semen Handling

Semen collections were made on Monday, Wednesday and
Friday from 3 a.m. to 7 a.m. All bulls were ejaculated in
or near the breeding stable adjacent to the processing lab-
oratory. Immediately after each collection the vial con-
taining the semen was taken into the laboratory. The follow-
ing procedures were used:

1. The semen sample was observed for any gross
abnormalities.

2. The semen volume was measured and recorded.

3. The spermatozoa concentration and motility was
determined by the following technique:

A. A 1 ml. T. D. pipette was inserted into the
semen receptacle and .2ml. of semen was
pipetted.

(a) .1 ml. of the pipetted semen was transferred
to a 3 ml. (10 x 75 mm.) test tube contain-
ing 1 ml. Of sodium citrate dihydrate. This
tube, with the diluted semen, was inserted
into the photoelectric colorimeter and the
reading recorded as thousands Of Spermatozoa
per cu. mm.

(b) .1 m1. Of the pipetted semen was placed on a
sterile microscopic slide (body temperature)
and the spermatozoa concentration was estim-

ated objectively under the microsOOpe.

 

63

4. Semen which showed a concentration of 800 sperma—
tozoa per cu. mm. or above and also had motility rating of
70 percent or above was further processed. The semen was
diluted with buffered egg—yolk citrate prepared by the
method of Salisbury and associates (138). The range of di-
lution for the processed semen varied from 1:30 to 1:40.
Sixty-days after the start of the experiment, a combination
of 1,000 international units each of penicillin and strepto-
mycin was added per ml. of diluted semen.

5. Semen was then gradually cooled to 5° C. at the
rate of 15° per hour.

6. The semen was then placed in 8 c. c. vials, one—
fourth inch from the top. Paraffined corks were used as
stoppers. ‘

7. The tubes were packaged in special containers con—
taining ice for parcel post, special delivery and air ship-
ment to the inseminators that morning or afternoon. Thus,

the semen used for insemination was never over three days

old when the cow was bred.

Procedure of Making Semen Smeags for MorphOIQgical Studies

Smears were made of the fresh semen from each bull to
determine the percentage of abnormal spermatozoa. The semen
smears were made immediately after recording the volume by
the following technique: (1) A small, sterile stiring rod was

cautiously introduced into the calibrated semen receptacle to

 

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64

transfer a small drop of the semen to a small, two—inch test
tube, 2 ml. capacity, containing .5 ml. of physiological
saline. (2) The contents of the test tube were then poured
on the entire flat surface of a sterile microscopic slide and
allowed to air-dry at laboratory temperature. The semen smears
were then taken to the nutritional laboratory for the stain—
ing technique. The following staining method was used to il-
lustrate the head, midsection, and tail of the sperm,
Gradwohl (60).

A. Fixation in Schaudinn's solution:

1. Immerse for one minute in 7 percent solution
of corrosive mercuric chloride, 2 parts, and
absolute alcohol, 1 part.

2. Immerse for a half—minute in 50 percent alco—
hol.

3. Immerse for a half-minute in 3 ounces of dis-
tilled water, and 2 drops of tincture of
iodine.

H. Wash in tap water.

B. Staining Process:

1. Immerse for a half—minute in aqueous solution
of 5 percent eosin.

2. Immerse for one minute in 3 ounces of 50 per—
cent alcohol and two drops of concentrated
hydrochloric acid.

3. Wash in distilled water.

- #. Immerse for two and one—half minutes in

65

hematoxylin.

5. Immerse for one minute in 3 ounces of dis—
tilled water, and 2 drops of glacial acetic
acid.

6. Wash in distilled water.

7. Dry at laboratory temperature.

Method of Counting Spermatozoa

Each stained slide was placed on a movable microscope
stage and following a standard technique of moving the slide
about, 250 individual spermatozoa were examined and classi-
fied as to morphological type.

Spermatozoa were classified into the following groups
suggested by Salisbury and associates (39):

l. Horphologically normal.

2. True abnormals, which included such types
as those possessing any abnormality with re—
spect to the shape or size of the head,
spermatozoa with enlarged, abaxial, beaded or
filiform middle-pieces, and those with thick—
ened or double tails.

3. Tailless spermatozoa.

4. Spermatozca with broken necks.

5. Spermatozoa with coil tails.

The number and types of normal and abnormal spermatozoa

found were recorded and these figures multiplied by four to

66

give the number of abnormal spermatozoa per 1,000. The ex—
aminations were made at #30 X magnification with a high—dry
objective. In addition to noting the abnormal spermatozoa,
observations were made as to the presence of debris, epithe—
lial, and primordial sperm cells in the semen. In recording
the abnormal spermatozoa, the following system was followed:
using a bacterial counter, 62 spermatozoa were counted in
each corner of the microscope slide, in some cases, this
procedure could not be followed due to the absence of cells
on some slides. Each sperm cell was recorded in its respec-
tive classification as it was counted. No SpermatORMX1was
included in more than one group. Hence, a pyriform head that
was tailless or coil-tailed. For this reason the percentage
of each abnormality is not absolute but represents only the
abnormal types that fall in their group after other forms
have been separated out. Since many of the coil-tailed and
tailless spermatozoa possessed other defects, it can be seen
that the values for these two forms will be somewhat high in

comparison to the other two types of abnormals.

Weights of the Bulls

Weights of the individual bulls were taken approximately
at six-week intervals during the course of the eXperiment.
All bulls were weighed at the same time each day. The regu-
lar weighing time was 10:00 a.m. so as to eliminate the pos-

sible error of feed consumption, upon body weight.

67

,Eyaluatinn the Degree of Libidg

The procedure used was to note the length of time in
minutes or fractions of a minute that elapsed from the time
the bull was two to three feet from the teaser and the com—
pletion of service to the artificial vagina. In a few cases
some bulls were retarded in their sex drive by the leader
forestalling the bull's mount. This time that a bull was

hindered in libido was not recorded.

Observations on Appetite and General Activity

During the experimental period, close observations were
made upon each bull to detect any noticeable changes in

appetite and activity.

its .1.E$§afl.gfigh=_ .

68

EXPERIMEKTAL RESULTS

Breeding Efficiency

A summary of the numbers of cows bred monthly and the
breeding results for treatments and breeds are found in
Tables VII and VIII.

The Holstein bulls had a considerably higher breeding
efficiency than the Guernseys. The percent of non—returns
for the Holstein breed was much higher on both exercise and
non—exercise than those for the Guernseys. The Holsteins
not exercised exceeded the exercised group by .8 percent in
total 60—90 day non-returns; whereas, the Guernseys that were
exercised showed 1.6 percent more total non—returns than the
non-exercised group. Figure 1 shows graphically the monthly
percent of 60-90 day non—returns for treatments and breeds.

The data for breeding efficiency were analyzed on fer—
tility levels by analysis of variance and the results are
presented in Tables IX and X. A highly significant differ-
ence of the average of non-returns was found between breeds
and between months in the high fertile bulls. No signifi-
cant differences were shown by the lcw fertile bulls. The
treatment interaction, exercise X breeds, was significant in
the fertile group, but not in the bulls of low fertility,
meaning that in the high fertile bulls, the Holstein did not
respond the same as Guernsey bulls for exercise and non—ex-

ercise. As shown by the analysis of variance, there were not

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Fig. 10

Percent of 60-90 Day Non-Returns

If.“
Holsteins - Exercised
-- Holsteins - Non-exercised
.... Guernseys - Exercised
_ __ __ __ Guernseye -- Non-exercised
Legend
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72

TABLE IX

ANALYSIS OF VARIAhCE OF PERCEIT .
FOR HIGH FERTILE BULLS

 

 

 

 

 

 

 

 

Source of Degrees of Kean

Variation Freedom Square F
Exercise 1 15.0 .39
Breeds 1 1,073.0 2E’>‘.01"”‘I
Months 5 150.5 4.19*‘
Exercise x Months 5 #8.6 1.27
Exercise x Breeds 1 251.0 6.55*
Breeds x Months 5 46.2 _ 1.21

-fl_ Exercise x

Breeds x Fonths 5 17.9 .47
Error 72 38.3 --

*Significant at the five percent level of probability
**Significant at the one percent level of probability

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—

73

TABLE X

ANALYSIS OF VARIAECE or PERCEIT won—RE
FOR Low FERTILE BULL

T’RES

 

N

H

 

 

 

 

 

 

 

 

Source of Degrees of Kean
Variation Freedom Square ' F
Exercise 1 lfl1.1 3.8
Breeds 1 1.2 .03
Months 5 14.4 .39
Exercise x Months 5 3.5 .09
Exercise x Breeds l .5 ..01
Breeds x Months 5 11.6 .31

Exercise x
Breeds x Months 5 12.3 .33
Error 55 37.0 --_-

 

w

a-.. A :I 311.141.... OI. 0.1.1.1 we... ..

74

significant differences in percent non—returns, in breeds
and treatments between months regardless of fertility levels.

Tables XI and XII summarize the breeding efficiency of
the exercised and non—exercised, high and low fertility
Holstein and Guernsey bulls. This data includes the average
percent non—returns during the course of the eXperiment, six
months prior to the experiment, and the corresponding six
months, one year before the experiment. An analysis of vari-
ance of these data showed no significance between the percent
non-returns for the three periods. However, this analysis
showed that there were highly significant differences between
the bulls for the three periods. This was more pronounced
with the Guernseys than the Holsteins.

Statistical analysis showed significant differences be-
tween the Holstein bulls in percent non—returns. The varia-
tion between the Guernsey bulls was highly significant.

Correlation coefficients between percent non-returns and
various factors were calculated in order to ascertain any real
relations between them. A highly significant correlation
(0.536) was obtained between percent non—returns and abnormal
spermatozoa. The higher the percentage of non—returns the
lower the percentage of abnormal spermatozoa. Significant
correlations were obtained between months in percentage of non—
returns for all bulls which means that non-returns for one
monthare Closely associated with those of other months. A
correlation of—O.539, which is highly significant, was obtained

between percent non-returns and age of the bulls. The younger,

75

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77

the bull (age 4 — 15 years), the higher was the percentage
of non—returns.

The correlation was less between the monthly responses
of the exercised and non-exercised groups of bulls, than
when all bulls were thrown together. Hence, it was thought
justifiable to do an analysis of variance for the exercised
and non—exercised groups separately. In some cases there
was a slight correlation between monthly responses and in

others there was no evidence of correlations.

Semen Characteristics

Volume

A monthly summary of the average semen volume for exer-
cised and non—exercised, high and low fertile, Holstein and
Guernsey bulls is presented in Table XIII. This table
shows that the non-exercised bulls produced .3 ml. more
semen per ejaculate than the exercised group.

Figure 2 shows the monthly differences in volume be-
tween high and low fertile bulls exercised compared to those
not exercised. The high fertile bulls on exercise slightly
excelled the high fertile group not on exercise; whereas,
the non-exercised low fertile group was slightly superior
to the low fertile bulls receiving exercise.

Exercised, high and low fertile Holsteins showed a

smaller average ejaculate than the correSponding groups not

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High Fertile Bulls Exercised
p—— ---Lo “Fertile Bulls Exercised

\\\ ....High Fertile Bulls Non-exercised
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81

exercised. High fertile Guernsey bulls exercised showed 1.6
ml. more semen per ejaculate as compared to the non—exercised

ah fertility. This was not true with the low

V.

Guernseys of hi
fertile groups as the non—exercised, low fertile Guernsey
bulls exceeded the group of low fertility on exercise.

Figure 3 is a graphical summary of the monthly volume
differences between exercised Holstein and Guernsey bulls to
that of the non-exercised. An examination of the monthly
averages showsthat the Holstein bulls on exercise were, in~
general, slightly superior to the Guernsey bulhanot exercised;
whereas the non-exercised Guernseys were superior to the ex-
ercised Holsteins. The Holstein bulls were slightly higher in
semen volume.

As shown in Table XIV and Figure 4, the volume of the
second ejaculate was larger than that of the first for both
the exercised and non-exercised bulls. The volume of the first
and second ejaculate of the bulls on exercise was somewhat
lower than those not receiving exercise.

Bulls of both breeds gave a greater volume of semen in the
second ejaculate than the first ejaculate. The Guernsey bulls
produced a greater volume of semen in the first (.5 ml. per
ejaculate) and second (.7 ml. per ejaculate) ejaculates than
.the Holstein bulls. This was the only semen characteristic in
which the Guernseys were superior to the Holsteins. These
data are summarized in Table XIV and presented graphically in

Figure 5.

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u.
.“n (
m— i, ._ ‘ ‘,
0

 

 

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Fig. 3. M1. Semen Per Ejaculateo

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83

 

 

 

 

 

 

 

 

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'100

Fig. 4.

-—--2nd Ejac.

_2nd Ejac.

Ml.

Legend
Exercised Bulls

Exercised Bulls
Non—exercised Bulls
Non—exercised Bulls

lst Ejac.

.....lst Ejac.

l

d

'AON
'ceq
°usf
'qeg

Semen Per First and Second Ejaculates.

.QIQN

 

{Envy-2v - .

a. .. ... N.H.§aJuI-.SJQ§9. .

 

 

Teresa
lst Ejac. - Holstein Bulls
-—--—2nd Ejac. — Holstein Bulls ¢“_

Guernsey Bulls ;
Guernsey Bulls

.....lst Ejac.
_2nd Ejac.

—_
0 ~‘_‘
&
.>.__.
. .o
o- .
" .
0 a
3
v.7 n;
a
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f;
‘ 1
7g .

 

 

L_.
7*.—
i.-

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'qex

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Fig. 5. M1. Semen Per First and Second Ejaculates-

 

 

4.: .4. 1,. ...-18“...le agar»... .

86

Since the data indicated a variation in volume of semen
between exercised and non-exercised, high and low fertile
Holsteins and Guernseys, anaanalysis of variance according
to the method of Snedecor (132) was made. No significant
differences in volume were obtained between exercised and
non-exercised, high and low fertile Holstein and Guernsey

bulls.

T tal SQermetozoa

Table XV presents a monthly sumaary of the average, total
spermatozoa per ejaculate for exercised and non-exercised,
high and low fertile, Holstein and Guernsey bulls. This table
shows that the exercised bulls were lower in total number of
spermatozoa per ejaculate than the non—exercised group.

Considerable monthly variation in total spermatozoa per
ejaculate was found between treatments and fertility levels as
indicated in Figure 6. The high fertile bulls that were ex-
ercised produced .15 billions yore soermatozoa per ejaculate
than low fertile exercised bulls.

' Non-exercised, high and low fertile, Holsteins were super-
ior to the corresponding groups exercised. High fertile, ex—
ercised Guernseys were slightly superior to the non-exercised
low fertile group.

A monthly summary of total Spermatozoa per ejaculate for

exercised and non—exercised Holstein and Guernsey bulls is

presented in Table XV and Figure 7.

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89

 

10 ...—...

 

Fig. 6.

Legend
High Fertile Bulls Exercised

—----Low Fertile Bulls Exercised
.....High Fertile Bulls Non-exercised
_Low Fertile Bulls Non-exercised

0
. \-
\
/J9‘ -- 3
h ‘ I /
o \ ..
; ' ’3' ‘
9
“Q .9. t
b, .
c. V. y, 1 ‘
e , 9’
J
r f,
r' (3
0 ,

—
_

. —
h—
——
—

'190
'AON
°oeq
°Uef
‘qag
'19“

Billions of Spermatozoa Per Ejaculate.

 

10

9O

 

 

Legend
Holsteins Exercised

 

 

w 0
.....Holsteins Non-exerC1sed
. -eveGuernseys Exercised
-_ “ . _____§uernseys Non—exercised
./ a
J—-—_‘ . ' ‘
* G
. \\.
Ii (é.
. o . 1“"; ‘ .
. -‘\ \\‘ ” . \\
“a N‘ "'
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g 'n -J l
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i
l ' g
(D 2: ti c. we ::
O O (D g (D SD
d' 4 o c' H
O O O O O 0

Fig. 7. Billions of Spermatozoa Per Ejaculate.

91

In non-exercised groups, the Guernseys were superior to
the Holsteins in numbers of spermatozoa per ejaculate. Ex—
cept for the month of February, the semen from the exercised
Holsteins was consistently of higher spermatozoa concentra-
ticn than that from the exercised Guernseys. Tne Holsteins
slightly xcelled the Guernsey bulls in the total number of
spermatozoa per ejaculate._

The semen from the first ejaculates showed a higher tot—
al number of spermatozoa than that from the second ejaculates.
These data are presented in Table XVI and Figures 8 and 9.
These data show that the first ejaculates of the exercised and
non-exercised bulls contained a higher number of spermatozoa
than did the second ejaculates. The first ejaculates from the
bulls not exercised had a larger number of spermatozoa per
ejaculate as compared with the ones from the exercised group.
The total number of spermatozoa per second ejaculate was
higher for the bulls on exercise than those receiving no exer-

cise.

Both breeds gave a greater number of spermatozoa in the
first ejaculates than in the second.

In total Spermatozoa, the first ejaculates of the Holsteins
slightly excelled the first ejaculates of the Guernseys; where—
as, the second ejaculates of the Guernseys had .2 billions more
spermatozoa per ejaculate than the second ejaculate from the
Holsteins.

An analysis of variance of the variation in total spermatozoa

 

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93

 

* Legend
11 let Ejac.‘ Exercised Bulls

----2nd Ejac. - Exercised Bulls
.....lst Ejac. Non-exercised Bull
_2nd Ejac. Non-exercised Bulls

.- ... ..-.-

10 e...
5
'v
9
l
K
8
'I— 3 U3 . O
0 O
9 t
C’ Q
‘9 , r
0
9
6 .—

 

\ ——

 

'190
‘AON
'oeq
'UBf
'qeg

Fig. 8. Billions of Spermatozoa Per First
and Second Ejaculations.

'Jew

 

 

..., suites—.3411udisfiufie ..

91+

 

Legend
10 ‘___ lst Ejac. - Holstein Bulls
----- 2nd Ejac. - Holstein Bulls
.....lst Ejac. - Guernsey Bulls
_gnd Ejac. - Guernsey Bulls
a A.
f or
a o 'a)/{
8 I ./ ,6 my
0 I
c ’f
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g, . o
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l l J L

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‘400
'AON
°oeq

Fig. 9. Billions of Spermatozoa Per
First and Second Ejaculates.

°an

 

 

deg. .fifijlfllnn.g§a .

 

95

per ejaculate, for the exercised and non—exercised, high
and low fertile, Holstein and Guernsey bulls, showed no sig-

nificance between treatments, fertility levels and breeds.

Apitial Fotility

The percentage of initial motility showed less variation
than any other semen characteristic. A monthly summary of
initial motility for exercised and non—exercised, high and low
fertile Holstein and Guernsey bulls, is presented in Table
XVII. This table shows that the non-exercised bulls exceeded
the exercised group by 1.7 percentage units in initial motility
of the spermatozoa.

Figure 10 presents graphically a summary of the monthly
variations in initial motility for high and low fertile, ex-
ercised, and for the same group, not exercised. The high fer—
. tile group, exercised, was superior to the high fertile group
not exercised; whereas, the low fertile group not exercised
was higher in initial motility than the exercised low fertile
bulls.

Both groups, the low fertile Holsteins and Guernseys non-
exercised, were superior in initial motility as compared to
the high fertile Holsteins and Guernseys exercised; whereas,
the exercised, high and low fertile Holsteins and Guernseys
show a higher percentage of progressive motile spermatozoa
than the corresoonding groups not exercised.

A summary of the monthly differences in initial motility

r0
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m.mm m.m5 m.M5 0.m5 W H.wm :.mm H.55 H.m5 .p00
0 m... 0 m m a m 0 m
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97

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m. m. . AH. M5% .55
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%
80 _ O
i
f \
9 ' ‘1:
n
I O
o * ‘ 9
a
a c
70 __ O ‘ “+3: ‘ ‘
a
fi . Legend
ngh Fertile Bulls
Exercised
. ————— Low Fertile Bulls
. :wExercised
97 .....High fertile Bulls
Non—exercised
. 2 Low Fertile Bulls
60 (~ '——"‘ . .
—— J Non—exerc1sed

 

 

L.

 

'100
'AON
'oeq

Fig. 10. Initial Motility Per

t. In :3

ca m m

D C" "3
Ejaculate.

 

...”...éaflqdilléar.

 

between exercised Holsteins and Guernseys may be found in
Table XVII. Table XVII and Figure 11 indicate that the in-
itial motility of exercised Holsteins was lower than that of
the Guernseys receiving exercise. In the non-exercised
group, the Holsteins were higher than the Guernseys. The
Holstein bulls slightly exceeded the Guernseys in percent of
progressively motile snermatozoa.

Table XVIII shows that spermatozoa motility in the first
ejaculation is poorer than in the second ejaculate except for
bulls on exercise. The average motility ratings of the first
and second ejaculates for the treatments are graphically pre—
sented in Figure 12. It can be seen that the motility from
the second ejaculates of the non—exercised bulls was 1.3 per-
centage units higher than the first ejaculates. However, a
comparison of the exercised bulls shows that the first ejacu—
lations contained .8 percent more motile spermatozoa than the
second ejaculates. In the two treatments, the motility of
the first and second ejaculates of the exercised bulls were
superior to those of the non-exercised bulls.

Figure 13 presents the monthly and breed variations in
percent of motile spermatozoa per first and second ejaculates.
As shown by this Figure and Table XVIII, the motility of the
first and second ejaculates did not show a striking difference
between the Holsteins and Guernseys.

As with the volume and total number of spermatozoa, an
analysis of variance of average motility ratings for the ex-

ercised and non-exercised, high and low fertile Holstein and

‘50.

80

7O

60

100

 

F"“‘” - .---w_____l_.. -.- ,-
In”...
J U 5.
Le end
Holsteins Exercised
....‘Holsteins Non-exercised
H-evvduernseys Exercised
_fiuernseys Non-exercised
I.-..

 

 

__-...-—___-.m~.‘-

.wan—— .—-A .....—~.—— _—-_ -- .-

 

'100
'AON
'oeq
°uef

qeg
'JBW

Fig. 11. Initial Motility Per Ejaculate.

a..§.e..i.a..

 

 

lOl

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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o.m5 m.:5 m.m5 m.H5 M m5 m5 m5 m5 auasnpme
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5.m5 H.m5 H.m5 w.m5 M «5 m5 m5 w5 HmpEmomo
5.m5 m.H5 m.»5 o.m5 M m5 H5 m5 m5 empameom
m.M5 m.H5 m.m5 055 H5 m5 m5 05 H3800
«Hmmceost maHmpmHomH M IomHmemxmuewz MmHOmem apnea

 

mambaq HHHHHBmmh ho wmquM4wmm
muoHB¢4304bm onomm Dm< BmMHh ho whHHHBOA HdHHHEH ho madamemmm

HHH>M aqmde

‘102

 

 

 

 

 

%
80 .
,,o
,/
P -~--o * "V”
o , c ----- o\
\ ‘ \\
_ -\ \ \
_ . \
.-‘ , ._O 0
\ :35. l o z A
o . U 7 :TJIF ; "'0 04 ‘.
_/‘ o . r ' ' K
x/ 0" . 3
7O "/ do
Legend
. lst Ejac. - Exercised Bulls
-—~—2nd Ejac. - Exercised Bulls
.....lst Ejac. - Non-exercised Bulls
_2nd Ejac. - Non-exercised Bulls I
60 4_ i

 

'qu
'AON
'oaq
'UBf
’QGJ
'JBW

Fig. 12. Initial.Motility Per First and
Second Ejaculates.

103

 

 

%
80 ._,_
°.' --
4 'l
g l»
70
Legend
lst Ejac. — Holstein Bulls
-—-—2nd Ejac. - Holstein Bulls
.....lst Ejac. — Guernsey Bulls
_2nd Ejac. - Guernsey Bulls
60 ...

 

 

'400
mm
'oeq
°uep

0.9.21

Fig. 13. Initial Motility Per First and
Second Ejaculates.

'JBN

104

Guernsey bulls, showed no significance in treatments, fertil-

ity levels and breeds.

Abnormal Spermatozoa

A monthly summary of abnormal spermatozoa for exercised
and non—exercised, high and low fertile Holsteins and Guernsey
bulls is given in Table XIX. This table indicates that the
non-exercised bulls produced 1.4 percent more abnormal spermap
tozoa per ejaculate than the exercised bulls.

The exercised high fertile bulls, showed 3.9 percent less
spermatozoa abnormalities as compared to the high fertility
group not exercised; whereas, the low fertile exercised bulls
reproduced 1.0 percent more than the low fertile non-exercised
group.

The monthly variations of the tree ments by breeds accord-
ing to the percentare of abnormal spermatozoa in their senen
are shown in Figure lfis. These variations are markedly pro-
nounced. The Guernsey bulls exceeded the Holsteins in percent
of abnormal spermatozoa. The semen from exercised Holsteins

honed an average of 5.9 percent less abnormalities than those
not exercised; whereas, the semen from the exercised Guernseys
had an average of .2 percent more abnormal spernatozoa than
those not receiving exercise.

A conparison of the non—exercised groups indicated that
bulls of high fertility produced .1 percent more abnormal sperm—

atozoa than the low fertile bulls, and the exercised bulls cf

105

 

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A

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106

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18

12

107

 

 

 

 

 

,.'4‘\
v . ” \
\.
u.— ‘__ _ \ .
:c ‘\_ ‘5
Legend
. Holstein Bulls Exercised
-. H—Guernsey'Bulls Exercised
.........Holstein Bulls Non-exercised
__._,Guarnsey'dulls Non-exercised
l :_ I - i I 5 A A“
O a? 3 is“ 3 3%
9+ <= 9 E” 9' r3
Fig. 14.

Percent Abnormal Spermatozoa.

 

.AHHQ’Mua I . . -

 

 

high fertility contained 9.8 percent less abnormalities than
the low fertile group. These data are presented monthly in
Figure 15.

Exercised high fertile Holsteins contained 3.9 perdent

1 ss spermatozoa abnormalities per ejaculate than the non—

(D

exercised group. This was also true with the low fertile ex—
ercised Holstein bulls which had 2.0 percent less abnormal
spermatozoa oer ejaculate as compared with the non—exercised
group.

The data shown in Table X. indicates that the first ejac—
ulation contained more abnormal spermatozoa than the second
ejaculates. It is evident that the first and second ejacul—
ates of the exercised group vere decidedly lower in abnormal-
ities as compared to the group not receiving exercise, Figure
16..

A summary of the monthly variation in percent abnormal
spermatozoa for first and second ejaculates of the Holstein
and Guernsey breeds is graphically presented in Figure XVII.
These data show that the first and second ejaculates of the
Guernsey bulls were higher in percent abnormal spermatozoa
than those of the Holsteins.

According to an analysis of variance, there were no sig-
nificant differences in the percent abnormal spermatozoa be-

tween treatments, fertility levels, and breeds.

109?

 

High Fertile Bulls
.....High Fertile Bulls

Low Fertile Bulls
24 "' ______Lothertile Bulls

 

93

W9".

 

Legend

Exercised
Non-exercised
Exercised
Non-exercised

 

 

'100
'AON
°oeq
.ugf

Fig. 15. Percent Abnormal Spermatozoa.

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fix qu¢a

ll].

 

21’ ‘— Legend

lst Ejac. Exercised Bulls
-—-—22nd Ejac. Exercised Bulls
.....lst Ejac. - Non-exercised Bulls
_____2nd Ejac. Non-exercised Bulls

0
F \u'
. I pf,‘
, \
\ (1 \ 2
l l 1' \
a 4 _ h .. .‘
12 _____1 I! x; g // .3 '\.~_,
I’ z
u ’ /’ £
a / a’

9

 

"mo
‘AON
°oeq
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'Qes
.13“

Fig. 16. Percent Abnormal Spermatozoa Per
First and Second Ejaculates.

 

Nunez? .. '1' .II a. Adair. .

 

112

 

 

24 [“‘ Legend
C lst Ejac. - Holstein Bulls
--—-2nd Ejac. - Holstein Bulls
oocoolSt E380. " Guernsey 311118
‘_2nd Ejac. — Guernsey Bulls
18 ‘___ g'
1!"
"If
, a 9
\\ .
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12 // “
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’ x”, e
f’ D
a? t ‘ W
a}
6 +__ E

 

 

 

'100
'AON
'oeq
°uep
°qeg
°Jew

Fig. 17. Percent Abnormal Spermatozoa Per
First and Second Ejaculates.

113

AIypes of Abnormal Spermatozca

A sunrary of the abnormal types of spermatozoa for the
treatments and fertility levels, regardless of breeds, is
presented in Table XXI. There seemed to be no one particular
type of abnormality associated with exercised or non-exer—

1

cised bulls. This was also true with fertility levels. The
main distinguishing characteristic between spermatozoa of
bulls of high fertility and those of low fertility were the
percentage of total abnormal spermatozoa. There were excep—
tions to the above statement in that some bulls with semen of
abnormal morphology were high in percentage of non-returns,
and that other bulls of low fertility had semen with few mor-
phological defects.

The abnormal types of spermatozoa for exercised and non-
xercised Holstein and Guernsey bulls, regardless of fertil—
ity level, is suemarized in Table XXII. This table shows that

the non—exercised Holsteins and Guernseys exceeded the exer-
cised group in percentage of coiled tailed, tailless, and true
abnormal spermatozoa; whereas, the broken neck spermatozoa
were slightly higher in the exercised Holstein and Guernsey
bulls than in the non—exercised groups.

The most common abnormal form encountered was coiled
tailed spermatozoa followed closely by the tailless. The next
host common abnormal type was true abnormal including such
forms as those possessing any abnormality with respect to the

shape or size of the head, spermatozoa with enlarged, abaxial,

 

114

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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116

 

 

 

 

 

 

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117

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11S

beaded or filiform middle pieces, and those with thickened or
double tails. Spernatozoa with broken necks were relatively

rare as compared to the coiled tailed and tailless.

901191 r9113

Figure 18 presents graphically the monthly variations in
coiled tailed spermatozoa for treatments and fertility levels.
A study of this graph indicates that the semen of exercised
high fertile bulls contained decidedly less coiled tails than
any of the other experimental groups. In the non—exercised
groups, the high fertile bulls produced .8 percent more coiled
tails per ejaculate than the low fertile bulls. A comparison
of the bulls of low fertility shows that the group on exercise
had .6 percent more coiled tailed spermatozoa per ejaculate
as the bulls not exercised.

Table XXIII shows the percentage of the types of abnormal
soermatozoa for treatments and ejaculates one and two. A study
of this table shows that first and second ejaculations of the
bulls on exercise contained a lower percentage of coiled tailed
spermatozoa than those not receiving exercise. Of the non—ex-
ercised group, the second ejaculation contained .5 percent more
coiled tailed spermatozoa per ejaculate than the first ejacu—
lates; whereas, the first ejaculates of the bulls on exercise
showed .1 percent more per ejaculate of this abnormality than

the second ejaculation.

119

 

i9 '

 

 

 

 

 

3 4 fl
’
Legend
High Fertile Bulls Exercised
l Low Fertile Bulls Exercised
.....High Fertile Bulls Non-exercised
0 _Low Fertile Bulls Non-exercised
L... “"
d::_ I J l I l I l --j»
C) 22 c: ¢4~ *s t!
o . o ‘m g m m
5* .4 5° . E" i‘

Fig. 18. Percent of Coiled Tails.

5:32.131 -fliwfllig?

120

 

 

 

 

 

 

 

 

 

 

 

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121

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Tailless spermatozoa

Figure 19 shows graphically the wide variation of tail—
less epermatozoa for the treatments and fertility levels. The
number of epermatozoa without tails was slightly higher in the
non—exercised bulls, (Table XXII). Both the low and high
’fertile bulls receiving exercise were higher in tailless sperm—
atozoa as compared to the corresponding groups not exercised.
In both treatments, bulls of low fertility were higher in per—
centage of tailless spermatozoa than the high fertile groups.

As was true with coiled tails, this type of spermatozoa
abnormality was slightly higher in the first and second ejacu—
lation of the non—exercised bulls as compared to the exercised
group, (Table XXIII). In both groups, the first ejaculate con-

tained a higher percentage of this abnormality.

Broken Necks

This abnormality was not noticed in all ejaculates. Bulls
that received exercise showed .1 percent fewer broken necks per
ejaculate than those bulls not on exercise, (Table XXII). Ex—
ercised bulls of high fertility had slightly more broken necks
than those of low fertility. This was also true in the case of
the corresponding groups not on exercise. These data are pre-
sented graphically in Figure 20.

A comparison of the first and second ejaculates in Table
XXIII indicates that the first ejaculates generally contained

more of this type of abnormal spermatozoa than the second

l—J

Ari
rh!

‘12}

 

 

 

 

e
\
9 .... ‘
\
\
\ p
6 1F 0 \(\ I.” “
l \ x
x
. \ K ,\
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.1. ‘\ Q. '0' , \\ ”’8'
o «9'. ” /“ ’\
3 ‘— 6 \ E—W °-- /- /:\\"\\\
l .,, '
Legend
_____fligh Fertile Bulls Exercised
----Low Fertile Bulls Exercised
.....High Fertile Bulls Non-exercised
_Low Fertile Bulls Non-exercised
O ah
4.5] l L l I J__'_J
C) 2: c: ta *s E:
o o o m o
F .4 .° 5’ 9‘ t‘
Fig. 19. Percent Tailless Spermatozoa.

 

 

 

 

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e
0 .
a
L.- .I/N.‘
;/ .
“f is.
9' _ Q
1 0,
— (-
.‘ P
Fl“ 9 'v I
a . I
e
lasers.
High Fertile Bulls Exercised
---«Low Fertile Bulls Exercised
___, .....High Fertile Bulls Non-exercised
_LOW'Fertile Bulls Non-exercised
a e e e a s
5* :4 9 .5 9‘ 11
Fig. 20. Percent Broken Necks Spermatozoa.

..-rJhSKZi- ..Efiflflmifi.

125

ejaculations. This fact was especially true of the exercised

bulls.

True Abnormal spermatozoa

This type of abnormality consists of forms of spermatozoa.
Figure 21 shows the wide variation between months, treatments,
and fertility levels. The non—exercised groups had a larger
number of true abnormal spermatozoa than the exercised bulls,
(Table XXI). In the non—exercised group, the bulls of high
fertility showed .6 percent more true abnormals per ejaculate
than those of low fertility; whereas in the exercised groups,
the low fertile bulls produced .6 percent more of the abnormal-
ity per ejaculate than the high fertile bulls.

The Holstein bulls produced more true abnormals than the
Guernsey bulls (Table XXII). The non—exercised Holstein and
Guernseys had a larger number of this abnormality than those
breeds on exercise.

The first ejaculates were higher in true abnormals than
the second ejaculates for both exercised and non—exercised

bulls, (Table XXIII). *

30:11 Tfeigz'ht of Bulls

Individual body weights of the bulls were taken at approx-
imately six week intervals. The initial and final weights of
the exercised and non—exercised groups are shown in Table XXIV.

Both groups of bulls gained in body weight. The 16 bulls not

L”?
JD
3
a
Ag
1%
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o q I
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1— ‘3 \ Q
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.r”
Legals
High Fertile Bulls Exercised
-—-~«Low Fertile Bulls Exercised
..c..High Fertile Bulls Non-exercised
'_Low Fertile Bulls Nonpexercised
_

 

 

‘100
'AON
°oeq
.ugf
'QQJ

’

Fig. 21. Percent True Abnormal Spermatozoa.

°xen

34 I‘VE—dud; . .. g;.
.Infi.‘ .d-flu

127

 

 

 

 

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128

 

 

 

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129

on exercise only gained 95 pounds more than the exercised
group. Only three bulls not exercised lost body weight;

whereas, only two bulls exercised lost body weight.

Degree of Libido

bull
The time reouired for each/to mount the teaser for each

collection was recorded. Ejaculation frequencies and the
mean mounting times for the bullsareagiven in Table XXV. It

is evident from these data, that no real differences existed.

130

TABLE XXV

EJACULATICH FREQUEKCIES A-D HEAN H UITING TITES
FOR THE IHDIVIDUAT BU'LS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E X E R‘G I S E i u 0 N — E X E R C I S E
Ejaculatione Time : Ejaculations Time
To. Fumber . ifinL : No. Pumper Vin;
High Fertile Holsteins
1 _50 .6 i 17 23 2.0
2 25 .1 i 18 22 .2
3 51 1.3 g 19 25 1.8
4 £1. 1.0 E 20 5g_ -2
Total 153 fig; 2 1;; 4{§____
Low Fertile Holsteins
5 29 1.7 21 11 1.6
6 29, I .9 22 16 3.§____
7 25 1.4 23 43 1.#

 

s 5 2.0 ,gu ' 19 .5

o. o. ’00 00 P. 00 no 00 on 00

_gptai as 6.0 as 2.3

 

1

0a

TABLE XXV(oontinued)

EJACULATION FREQUEKCIES AFD EEAN EOUFTIKG TIKES
FOR THE IEDIVIDUAL BULLS

 

 

j

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E X E R C I S E i N O N — E X E R C I S E
Ejaculations Time : Ejaculations ime
No.3 Fumher IfinL : No. Number Fin.
High Fertile Guernseys
9 as .0 E 25 25 .s
10 2M .1 E 26 29 1.5
11 23 1.2 : 2Z 19 .2
.....12 1}. 1... 28 2.3. was __._
:gptsl 11s 3.;1 : 96 2.5
Low Fertile Guernseys_
13 5 .o E_ 22 29 .6
14 18 .3 i 30 16 .1
15 10 h.1 i 31 18 1.5
__15 . 24 143 i 32 11 .6
Total 52 Sal l: 74 2.8
Grand Tot. 416 17.0 g 381 16.8
Av. Sec. 2.4 : 2.6

 

 

pal.‘

131
DISCUSSION

From the days of our forefathers, dairymen have been par-
ticularly concerned about the role of exercise in management
of bulls, and its relationship to maintainance and/or its im—
provement of reproductive efficiency.

A few previous workers have reported varying results.
martlett and Perry(19) found that regular 3 stematic exercise
of three bulls for one month gave a 51 percent increase in
volume. Woodward (160) reported that the exercising of bulls
for 30 minutes a day increased the motility (with exercise 60
to 100 percent of the spermatozoa were motile, while with no
exercise there was only 5 to 45 percent motility) and longevity
of the soermatozoa and greatly diminished the time of service
with a slow bull. Hamilton and Symington (65) observed that
daily exercise increased the volume, sperm concentration and
motility of the ejaculate. Lenard and associates (S7) noted no
significant effect of exercise on the morphology, concentration
and viability of the spermatozoa. The volume of the semen
showed a slight but insignificant increase in bulls receiving
exercise. They reported that the conception rate of the exer-
cised and non—exercised bulls followed the same general tend.
These results only show the value of exercise on the amount and
quality of semen for a sixteen weeks' trial.

It is not unlikely that some of this variability of pre-
vious results stems from a multiplicity of factors affecting the

potential fertility and characteristics of semen. No doubt, the

132

method of selecting the animals and the period of time the
bulls were exercised was a major problem. Bowling (28) and
Dawson (42) have indicated that age and health of the bulls
may have an effect upon breeding efficiency. That the fre-
quency of ejaculation may effect the breeding abilities and
fertility of the bull has been shown by Teatherby and assoc-
iates (149) and Lesley and Bogart (86). The season-of the
year effects semen quality and fertility of bulls as shown by
Lewis (38) Hercier and Salisbury (96). The data showing the
effect of nutrition upon reproduction is limited and somewhat
contradictory, but several investigators, Erb and co—workers
(50) and Hodgson and associates (72) have suggested that cer—
tain nutrients are concerned in normal breeding efficiency.

It is cocmonly thought by many dairymen that exercise is
an important factor in maintaining the production of high
quality semen in bulls over a long period. They believe that
exercise stimulates the appetite, influences the degree of
fleshing, and may be resnonsible for normal blood circulation.

It is aporeciated that the percentage of 60-90 day non-
returns is not as accurate in measuring bull fertility as 90-
120 day non—returns, however, the trends observed would have
probably remained the same.

As shown by the analysis of variance there were no signif-
icant differences in the percentage of non-returns between the
exercised and non—exercised bulls during the course of this
experiment. These results are in accord with those reported by

Lenard and associates (87).

evil-and, W334i;

133

Highly significant differences between breeds and between
months were found in the bulls of high fertility, whereas, the
low fertile bulls showed no significant differences between
breeds and between months. The interaction, breeds X exercise,
was significant in the high fertile bulls which indicates that
the high fertile Holsteins did not respond to exercise the
same way as the high fertile Guernsey bulls.

Highly significant differences in fertility of individual
bulls weie found during the experimental uariod. This was
more pronounced in the Guernseys than the Holsteins. These data
are similar to those reported by Lewis (88) and Salisbury (119).
The monthly variation in the percentage of non—returns was sig—
nificant between sone months but not for all months. The Hol—
stein bulls showed a consistently higher fertility than the
Guernseys.

Statistical analysis showed that there was no significance
between the oercentage of non—returns for the six months that
the bulls were exercised, the six months prior to the experimen—
tal period and the corresponding six nonths, one year before the
exercised period.

Bowling and associates (80) and Dawson (42) have indicated
that the age of the bull may have an effect upon the breeding
efficiency. The results of this study indicate that young
bulls have a higher percentage of non—returns than older bulls.

The findings of this study confirm the earlier resorts of
Erb and associates (51) and Anderson (13) that the higher the

percentage of non-returns the lower the percentage of abnormal

spermatozoa. In view of the difference in fertility level
observed between the Holsteins and Guernseys, it was interest-
ing that the semen of the Guernsey bulls contained more abnor—
mal spermatozoa than the Holsteins. This may be one of the
factors responsible for the lower fertility observed in the
Guernsey bulls.

The bulls on exercise produced senen with less volume,
with fewer total spermatozoa, with lower initial motility, and
less abnormal spermatozoa than the non-exercised bulls, but
the differences were not significant. These data confirm the
work of Lepard and associates (87). The findings of this study
disagree with those of Woodward (160) who found that exercise
greatly diminished the time of service with a slow bull. The
results obtained here showed that libido was not affected by
exercise.

These data indicate that the management practice, exercise,

q

did not have an effect upon the body weigats, appetites and gen-
eral activities of dairy bulls for a six months period. If the
aged theory, that exercise has an effect upon the breeding ef-
ficiency is to be clarified, an exueriment involving a large

number of young and old bulls will have to be planned for a long

periOdo

135

SUMMARY

Thirty—two Holstein end Guernsey bulls, owned by the
Michigan Artificial Breeders' Association, varying from
four to 15 years of age, were divided into eight groups
according to their breed and to high or low fertility.
All animals were fed and Kanaged similarly .xcept for
exercise. During the first 35 days one—half of he bulls
were exercised for 15 minutes a day on a mechanical ex—
erciser with a speed of 1.24 mi. per hr. The amount of
daily exercise was increased to 23 minutes at the same
rate of speed for the following 14 days. For the remain;
ing 119 days of the exoeriment these same bulls were ex—
ercised daily for 30 minutes at the rate mentioned above
on the mechanical exerciser. The other 16 bulls were
left in their stalls during the six months oeriod. 452
semen collections and 33,292 breeding records were tabu-
lated in this study.

No significant differences in the percentage of non-returns
were found between the exercised and non—exercised bulls.
Highly significant differences in percentage of non—returns
were found for individual bulls during the exoerinental
period.

Highly significant differences in the percentage of non-
returns between breeds and betveen months were observed
in the high fertile bulls.

No significant differences were found in the percentage

10.

11.

12.

13.

11+.

136

of non-returns between breeds and between months in the
low fertile bulls.

A breed difference in resnonse to exercise was signifi-
cant in the high fertile bulls.

The monthly variation in the percentage of non—returns was
significant between some months, but not for all months.
”he Holstein bulls showed a consistently higher fertility
than the Guernseys.

Kc significant differences were found in the percentage of
non—returns for the six months that the bulls were exer—
cised, the six months prior to the experimental period,
and the corresponding six months, one year before the ex—
ercised period. This was also true with the non—exercised
bulls.

A highly significant correlation L£L539) was obtained be—
tween the age and the percentage of non-returns.

A correlation of-O.536, which is highly significant, was
obtained between the percentage of non-returns and.the
percentage of abnormal spernatozoa.

ho significant differences were noted between the exercised
and non-exercised bulls in the semen characteristics
(volume, total spermatozoa, initial motility and abnormal
spermatozoa).

A breed difference in percentage of abnormal snermatozoa was
evident, but not significant.

Libido was not affected by exercise.

fig... ......lli 3...... 5:3.

 

137

15. The body weights between the exercised and non—exercised.bulls

show little variation.

l.

9.

10.

13S

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'I"

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((1)

 

 

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39: I’LL}.

 

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