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has been accepted towards fulfillment

of the requirements for

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Major professor

 

Date October S, 1951.

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Submitted to tne School of Gr luate Studies of Michigan
State College of Afiriculiure ;nd Applied Science
in partial fulfillment of the requirements

for the degree of

Department of Animal Husbandry

1951

THESIS

ACKNO". EDGE-H3138

The author feels pleasure in expressing his sincere appreciation
and most grateful thanks to Dr. Leonard H. Blakeslee, Associate Professor
of Animal Husbandry, for his assistance, guidance, great concern and con-
stant encouragement in the conduct of this work, and for his invaluable
criticism in the preparation of this manuscript.

The author is also indebted to Dr. William D. Eaten, Professor of
Lhthematics, for generous help in the mathematical a alysis; to the United
States Weather Bureau for furnishing meteorological data; and to Mr. Lee
Bell, Shepherd of the College flock for cooperation during the course of

these studies.

263337

II

III

VI

“7

A

XI

I
II”: RCDUCT ICI‘T O O O O O O O O O O O O O O O O I O O O O O O O O
PURPOSEOFSTUDY...............
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.L'Lt-LlLRLLLaOOoooococoa-00.000.00.000.

(a) Housing . . . . . . . . . . . . . . . . . . . . . . . . .
(b) Feeding and Watering . . . . . . . . . . . . . . . . . .
l-EmHOD OF OBSERVPTIOII . . . . . . . . . . . . . . . o . . . .
(a) Beha iour of Ram . . . . . . . . . . . . . . . . . . . .

(E) EBhaViOlu‘ Of E'VICS o o o o o o o o o o o o o o o a o o o o

(0) Signs of Testrus . . . . . . . . . . . . .

VISUAL OESLZRVATIQIB CF DESTRUS II T133 EXPERDZQZEKJJ HES FRO}:

JANUARY 15 TO AUGUST 31. . . . . . . o . . . . . . . . . . . .
(a) Dorset Horned Ewes . . . . . . . . . . . . . . . . . ...
(b) Hampshire Ewes. . . . . . . . . . . . . . . . . . . . . .
(c) Oxford Ewes . . . . . . . . . . . . . . . . . . . . . . .
(d) Rambouillet x Dorset Horned Ewes . . . . . . . . . . . .
(e) Shropshire Eves . . . . . . . . . . . . . . . . . . . . .
(f) Southdown Ewes . . . . . . . . . . . . . . . . . . . . .
(g) Suff 1k Ewes. . . . . . . . . . . . . . . . . . . . . . .
DURAT CH OF OESTRUS . . . . . o . . o . o . . . . . . . . . .
(a) Duration of Oestrus in the Different Breed Groups . . . .
DIOIJSTRUS PLRIC'D . o . . . . . . . . . . . . . . . . . . . . .
OESTRUS CYCLE. . . . . . . . . . . . . . . . . . . . . . . . .
0:311? T THE ‘FQEZIXG SEASCN . . . . . . . . . . . . . . . . .

I‘m"? “'TC‘ ""I 777’ ‘Tl'r‘fi'
O-LJQ—F-l-UQ J-L" «Ll-LU ILA-$41!“D o o o o o o o o o o o o o o o o o o o o o

10
13
15
17
2O

20

Table of Contents Continued

XII SBXULL BEHATICUR IN THE aanr;lue srnsom . . . . .
(a) Number and Percentages of Ewes Settled . . .
XIII DISCUSSICI. . . . . . . . . . . . . . . . . . .
(a) Duration of Cestrus . . . . . . . . . . . .
(b) Oestrus Cycle . . . . . . . . . . . . . . .

(c) Onset of the Breeding Season . . . . . .

(d) Modification of the Natural Breeding Season

(1) Length of Lieht Allowed . . . .

. (2) Temperature . . . . . . . . . . . . . .

-r. C! W" ~
4.10 U (4&1; o o o o o o o o o o o o o o o o o o o o o

XV SELECTED BIBLIOGRAPHY . . . . . . . . . . . . . .

Pd
vim
vum

C0
h)

Table
I 5e of Experimental Ewes on January 15, 1951 . . . . . . . .
II Number and Percentage of Ewes in Heat. . . . . . . . . . . .
III Occurrence of Oestrus in Dorset Horned Ewes from January 15
toA‘dsustfl
IV Occurrence of Oestrus in Hampshire Ewes from Januaryl5tolugust
31.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V Occurrence of Ce trus in Oxford Ewes from January 15 to August
31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VI Occurrence of Oestrus in Rambouillet x Dorset Horned Ewes from
January 15 to August 31 . . . . . . . . . . . . . . . . . .
VII Occurrence of Oestrus in Shropshire Eves from January 15 to
August 31 . . . . . . . . . . . . . . . . . . . . . . . . .
VIII Occurrence of Oestrus in Southdown Ewes from January 15 to
Aigust 31 . . . . . . . . . . . . . . . . . . . . . . . . .
IX Occurrence of Oestrus in Suffolk Ewes from January 15 to August
31 . . . . . . . . . . . . . .. . . . . . . . . . . . . . .
X Observed Duration of Oestrus in Different Breeds . . . . . .
XI Duration of Dioestrus Period in Different Breeds . . . . . .
III Duration of Oestrus Cycle in Different Breeds. . . . . . . .
XIII Age of Ewe Lambs at the Breeding Time . . . . . . . . . . .
vIV Dates of Turning In and Taking Out of Rams . . . . . . . . .
XV Number and Percentage of Hampshire Ewes Settled. . . . . . .
XVI Number and Percentage of Oxford Ewes Settled . . . . . . . .
XVII Number and Percentafe of Shropshire Ewes Settled . . . . . .

43

45

47

49
50
51
54
56
67
68
69

List of Tables Continued.

Table - Page
XVIII Number and Percentage of Southdown Ewes Settled . . . . . 7O

XIX Number and Percentage of Suffolk Ewes Settled. I. . . . . 71

Ti

\1
0

C0
0

gure

LIST OF FIGURES

Experimental Ewes on Pasture . . . . . . . . . . . . . .

Group of Ewes with

Average
Average
Average
Average
Average
Average
Average
Avercge
Haximum
Average

Maximum

Percentage
Percentage
Percentage
Percentare
Percentage
Percentage
Percentage

Percentage

the Ram Equipped at the Checking Time

Ewes in Heat Each Month . . . . .
Hampshire Ewes Settled Each fienth.
Oxford Ewes Settled Each Month . .

C‘s

Shropshire Ewes Settled Each Month
Southdown Ewes Settled Each Month
Ewes Settled Each Month, 1948-1949

Ewes Settled Each Month, 1949-1950

Ewes Settled Each Month, 1950-1951

and Minimum Day Length from January to Dec mber.

Max'mum and Minimum Monthly Temperat re at

and Minimum Temperature at East Lansing. . . . . . .

East Lansing

INTRODUCTION-

Domestication and breeding of sheep along with other livestock began
at a more remote period than the recorded history of man himself. Sheep
attracted the attention of mankind as a constant source of food and
clothing.

Knowledge about the prehistoric man‘s association with sheep is very
limited and therefore, precise information about the ancestral type of
this animal is also lacking. The Old Testament makes frequent mention of
the pastoral occupation of sheep herding. Thus it may be inferred that
sheep were of definite value long before that period. However, primitive
sheep were a very inferior stock, wool being of hairy character, thin and
of various colors.

For proper deveIOpment and reproduction ewes had to be protected
and properly fed. With the limited number of foundation stock, their
well being was all the more important in order to secure substantial in—
crease in number which could be relied upon when needed. Mere care and
haphazard breeding could not keep pace with the increasing demands of the
human population, therefore, need for better and more efficient animals
soon arose.

The improvement of livestock by controlling the parentage, goes

beyond the time of Egyptian Prince Hehenwetre, who ruled about 21 B.C. A

'_J

n

H-

chamber opened in the tomb of this Prince 91;, revealed that he owned

/
974 heaisof sheep in addition to the other livestock. A model illustrat-
ing the difference in type between the wild and improved animals showed

their understanding of the subject of breeding. Improvement of livestock

according to present day conception, however, began in about 1760 in the

time of Robert Eakewell, followed by the Ceiling brothers in 1783, Thomas
Eates and Thomas Booth.

Progressive breeders by this time began to realize a definite econ-
omic need for animals suiting different purposes which ultimately estab-
lished various breeds of livestock. Continuous efforts to effect im-
provement in meat and wool yields brought into being Ecol and Hutton
breeds of sheep.

Success of any enterprise is measured in terms of return it brings
as compared to its cost. In sheep enterprise, fertility is one of the
factors having direct bearing upon success. To achieve this, understand—
ing of the breeding habits of this animal is very important. It is of
paramount importance, therefore, for the breeder to know of any tendency
there may be in the seasonal breeding habits of a particular breed or
strain of sheep under his care. A knowledge of the trend of females to
come in heat and become fertilized during certain periods of the year
would lead to a more rational preparation and distribution of males dur-
ing such seasons and a consequent higher fertility and reproductive
efficiency of the females. Also, information concerning the reproduc—
tion of a greater number of youngs during certain months of the year is
advantagious as the breeder can provide adequate facilities so as to re—
duce the mortality to minimum.when reproduction occurs during unfavorable

months of the year.

PURPOSE OF STUDY

With the hepe of solving some of these problems, workers in differ-
ent countries have from time to time studied the occurrence of breeding
season among different breeds and ages of sheep in which they were inter—
ested. Precise information on the occurrence of the phenomenon beyond
the regular breeding season esgecially among young ewes under Michigan
conditions is not available.

A flock of yearling ewes practically of similar ages but of differ-
ent breeds, owned by the Michigan State College was found available to
work with in January, 1951. The opportunity was considered worth spend-
ing time and energy for the purpose of obtaining exact information re-
garding the sexual behaviour of this flock maintained under similar
dietetic and other environmental conditions through-out the period of ob-
servation, extending from January 15 to August 31, 1951.

*It is further hoped that the conditions imposed upon the animals
under observation being natural and thus identical with those prevailing
on an average farm would furnish equally identical results which could be

utilized without any further modification.

REVIEW OF LITERATURE

The breeding season is a certain period of the year when females
accept the males. Onset and termination of the breeding season differs
in different Species of animals. Yithin species, it is influenced by
breed, strain, heredity, age, nutrition and various environmental factors.
within breeds and strains, individual females exhibit certain differences
from time to time.

Cows are generally receptive to the male at regular intervals
throughout the year, although, majority breeds during Spring and late
Summer.

Hares, usually exhibit signs of oestrus during Spring, while some
breed regularly all the year round. Still others mate in Spring, Summer
and Autumn. A similar general statement about seasonal occurrence of
oestrus in sheep holds true. Breeling season in this species of live-
stock starts in late Summer and ends in early Winter. As in case of
other livestock, one finds variations among breeds, strains and individu-
al animals. Environmental conditions as nutrition, climate, season, etc.,
have a direct bearing upon the phenomenon as well. In addition to the
above, age is a factor of fundamental importance. The problem being of
vital importance for the industry has been a subject of study in almost
all the sheep breeding countries of the world.

Henning and HCKenzie (1927) while working with a group of Dorset and
Grade Merino ewes found that 38% conceived in June, 48% in July and 4% in
August with 8% cases ofrnmxnceiion in 1924.

Next year another group of Grade Merino and Dorset x Xerino ewes

were observed, out of which 84% conceived in June, 8% in July, 2% in

September and October each and 4% cases of nonconception.

Valente Villegas (1929) reported his findings on a group of Indian
Grade ewes. During the period of observation (1923-1928), 18.3% matings
took place from January to April, 39.3% in May and June, 21.2% from July
through November and 21.2% in December. This indicated two periods of
marked sexual activity instead of one as is the case with other breeds.

McKenzie and Phillips (1930) found that the breeding season started
in the end of August, Fampshire ewes started breeding 10 days earlier
than Shropshires and Soutldowns. Another group consisting of ewe lambs
representing the same breeds revealed that all the Hampshires had been in
first oestrus by October 19, while October 16 marked the beginning of
first oestrus in Southdowns as compared with Shropshires all of which ex-
hibited first oestrus by November 4.

Smith and Hussain (l935) observed that sheep were bred all the year
round in the Punjab (India) but maximum numbers of lambs were dropped
during Spring and Fall.

son in the

{D

Smith and Singh (1938) reported that regular breeding se
Punjab is Spring and Fall in Eikaner ewes. A study of 3 years breeding
records of Bikaner and Hissar Dale flocks maintained at the Government
Cattle Farm, Hissar, revealed that 823 of lambs were dropped in Spring.

Apart from the above, 2 groups of Bikaner ewes were observed from
Farah 15 to June 15. Large majority of ewes were settled by the end of
observation period (June 15), while ewes that did not settle were found
coming in heat regularly up to that date.

Observations detailed above fall in line with Valente Villegas who

also found that Indian Grade ewes have a tendency to breed twice a year.

McKenzie and Terril (1937) reported their observations on Hampshire,
Shropshire, Southiown, High Grade Rambouillet and Grade Hampshire x Shrop-
shire ewes from 1929 through 1936. Each year, observations started from
August and terminated when all ewes had stopped coming in oestrus. They
concluded that considerable variations existed in the onset and duration
of breeding season in different ewes under same conditions and same ewes

n different years. In spite of all these variations, breeding seasons

PJI

started in late August and beginning of September and ended by the end of
December or January.

Kelly and Shaw (1937, 1939, 1943) observed different strains of
Australian Merino, Dorset Horned, Leicester and Merino cross bred ewes at
centers 13° latitude apart. A well defined periodicity in the percentage
of ewes coming in heat was observed at all centers. Decrease in the in-
cidence of oestrus occurred in Spring months (Fall in U.S.) and rise in
Sumner and higher level was maintained in late Summer and Autumn through-
out the period of observation. Further, breeding season started earlier
in the Dorset Horned ewes while Marines exhibited relatively longer breed-
ing season as compared with Border Leicester ewes having a restricted
season. Variations with.in breeds were found characteristic of strains.

Schott, Phillips and Spencer (1939 in connection with hot House
Lamb Production project conducted at Hidileburry and Eeltsville observed

Corriedale, Dorset, Tasmanian Merino, Hampshire, Shron

.L

shire, Southdown,
Karakul and various other groups of crossbred ewes. The rams were let
loose in the flocks from may to the end of October each year. Ewes from
different breeds were in mating throughout the period of obserVation but

.'

lambs tended to be dropped in two ratner distinct periods around September

and January. The proportions of ewes settled in June, July and August
were small. In Corriedale, Dorset and Dorset x Tasmanian Merino ewes,
the proportions that settled during May were higher than in the three
succeeding months. Among Tasmanian herino ewes, none settled during July
and in Dorset x Tasmanian Merino and Dorset x Delane Merino ewes, none
settled during June.

Among the mature ewes in Corriedales, the first oestrus occurred
during the last week of July in 1938. Among the Hampshire, Shropshire,
Southdown, Karakul and Karakul crossbred ewes, the first oestrus occurred
from the second to fourth week of August, yearlings tended to come in
heat somewhat later than mature ewes.

Hammond (1944) reported regarding a flock of Suffolk x Border
Leicester Cheviot ewes that were allowed to run with rams throughout the
year from 1932 to 1939. The onset and end of the breeding season ranged
from September 18 to November 5 and February 17 to April 10 respectively.

Yeats (1947) reported, that phenomenon of seasonality in breeding
among sheep of British Isles is due to some stimulus of natural environ-
ments, rather than to an inherent rhythm and the idea had a support by
the evidence of reversal of breeding seasons when these ewes were trans-
fered to Southern Hemisphere. Consequently a group of ewesvnnssubjected
to varying lengths of light during 24 hours and the sexual behaviour ob-
served. He found that seasonal variations in the length of days is the
chief factor determining the onset and duration of natural breeding sea—
son, and that it can be modified and even reversed by altering the length
of days artificially. A change from increasing to decreasing length of

days induced reproductive activity, the breeding response occurred some

10-14 weeks after the change. On the other hand, a change from decreas—
ing to increasing length of the day, induced an-oestrum 10-14 weeks after
the change.

Gunn (1948) quoted breeding record of Australian Merinos from 1933-
1938 showing that the percentage of ewes settled in October, November,
December and January was lowest. From January onwards, the percentage of
conceptions showed rise and reached its peak in Nay, June nd July. From
July onwards, fall in conception percentage again resulted and reached

the lowest levels from about October. Onset of breeding seasons was how-

ever earlier than.the breeds of British origin .

MATERIAL

Animals used in the eXperiment consisted of young ewes dropped by
the College flock from KOVember 1949 to May 1950. To allow proper growth
and development, the ewe lambs were not bred during Fall, 1950. With the
exception of a group of Rambouillet x Dorset Horned, the entire flock con-
sisted of pure bred Dorset Horned, Hampshire, Oxford, Shropshire, South-
down and Suffolk yearling ewes. The number of females was different in
different breed groups and rather small except Shropshires. This problem
had no solution as no more animals were available. Deaths and other such
unavoidable causes were encountered during the period of observation,
that resulted in further reduction of number in different breed groups.

To start with, 47 young ewes consisting of Rambouillet x Dorset
Horned 8, Dorset Horned 3, hampshire 7, Oxford 5, Shropshire 16, South-
down 7 and Suffolk l, were available in January 1951. The ages of these
yearling ewes ranged from eight months and fifteen days to fourteen
months and fourteen days (Table I).

The rams used as teasers to check oestrus belonged to regular breed-
ing flock of Shropshire and Oxford breeds and after a trial of few days,
two of them were finally found suitable for this teasing work and used
throughout the period.

During Winter and early Spring, generally one of them was used for
routine daily checking. From about middle of may 1951, when the atmOSph-
eric temperature started showing rise, the teasing activity of the rams
was found decreased. It was therefore decided to;use two instead of one
to have reliable results. This scheme was then put into operation and

continued throughout the rest of the period.

-10-

In addition to the material mentioned above, information was also
collected from the breeding records of the College flock with the purpose
of determining the onset of heat in ewe lambs. It was also considered
worth-while to analyze the breeding records of adult females which might
show some difference in the sexual behaviour in relation to breeds and
individuals within breeds during the regular breeding season. Records of
breeding dates with respect to each ewe were not kept andeere calculated
from the lambing dates in each case.

Housing

The entire flock of young ewes observed in this experiment along
with check rams was h0u33d in the Experimental Barn in the beginning of
November 1950, when the animals returned from pasture. To provide the re-
quired housing Space of 12 to 16 sq. ft. per head, the animals were con-
fined in separate pens according to breed groups. Dorset Horned ewes were
only 3 and were consequently accomodated along with Ranbouillet x Dorset
Horned group. Similarly a Suffolk yearling ewe, the only representative
of her breed was also housed along with the Oxford group. On the whole,
the flock was scattered in 5 pens, one pen for each group of Pambouillet
x Dorset and Dorset Horned, Hampshire, Oxford and Suffolk, Shropshire and
Southdown ewes respectively.

From May 11, 1951, the flock was put on pasture and was then moved
to the Kain Earn. From here, the ewes could go and come back from the
grazing field at any time which was not possible from the Experimental
Barn. During the pasture period all ewes were put in one flock.

Check rams were also housed in one pen by the side of ewes.and were

kept separate by keeping the connecting door closed.

-11-

T’FLF I
gnu .J

AGE OF EXPERIHEWTA LESS N JANUARY 15, 1951

 

Date of Age on January 15, 1951

Birth Months/Days

Nov.
Apr.

 

 

 

 

 

 

 

 

 

_...__ 5.23....
meg eb.18/750
905 eb.;275O

50
912 >- 50
i ‘3
9

 

 

continued

-12-

Date of Birth Age on Jan. 5/51
lie/days .

o
O

 

 

'7 u‘LlffOlk

 

 

-13-

Feeding and Watering
while confined in the Experimental Barn from.November 1950 to May 11,
1951, ewes as well as rams were fed twice daily between 8 and 9 A.H. in
the morning and 4 to 5 P.M. in the evening according to the following
scale per head
Morning

Oats and Corn (equal parts) -%¥

Soyabean oil meal 1/10#

Corn silage 4#
Evening

Oats and Corn (equal parts) %#

Hay (mixed Alfalfa, Clover and Brome grass) 2?

Double sided feeding racks were provided, one for each pen where the
feed was placed each time. The animals were found scattered all around
according to their convenience and consumed their shares.

From May 11, 1951, the ewes were put on }asture consisting of 3
fields. Grazing in each field was done in rotation one after the other
to provide ample young grass:s. Field No. 1, 2 and 3 consisted of Ladino
Clover mixed with Alfalfa and Brome grass, Ladino Clover, Alfalfa, Alsike
and Brome grass and Birdfoot terfoil and Ladino Clover respectively (Fig.
1).

Throughout the period, rams had also the facility of grazing in
separate field from the ewes. Wholesome and fresh water was always a-
vailable in the Barn in each pen from cemented water troughs. Tlere was
no provision for water in the fields and the animals had to come to th

Barn whenever they were thirsty. For so doing they had to walk about 400

yards each way.

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-15-

METHOD OF OESLRVATION
Workers on similar projects have, from time to time used different
methods for detecting heat in ewes. Rams were allowed to run with ewe
flock all the trme by some and breeding dates calculated from dates of
lanbing. Others, used rams with painted breasts and ewes bearing color
mark on runps on the following day Jere assumed to be in heat. In either
case, rams ad to be withdrawn after some time for rest and replaced by a

’1

fresh group. Similarly, painting 0: breasts required constant attention
and frequent changes of colors to have correct readings. At every change
of color, clipping of runps was essenti0 to remove the previous stains.

Method No. I, described above seemed to provide no information about
the occurrence of oestrus in the same ewe in successive months which
formed main feature of the present investigation. Method No. II, on the
other hand seemed not very reliable, as a vigorous ram would mark at—
least some ewes even when they were not in heat.

Ior the purpose of obtaining reliable information etc., it was de—
cided to use aproned rams for checking the flock. The rams were hep
separate and only turned with flock at the time of checking. It was there-
fore, possible to continue using the same rams without replacements. here-
over every ewe was under direct supervision at the checking time each day ,
thus giving a true picture of the behaviour of different breeds and in-
dividual females constituting the flock.

From the very start of the experiment, it was decided that the flock
should be contented and satisfied when checked in order to have satisfact-
ory readings. Nornings and evenings both, being feeding times were unsuit-

able as the ewes were always found restless and bleating. Under the cir-

-16...

mstances checking in the afte1 noons was considered liore suitable. This

plan was adhered to as closelya spossible between 1 and 2 P. H. every day

.1

so long as the flock was confined in the Barn previous to may 11, 1951.
Everyday usually one ram was taken out from his pen with an apron
fitted around his neck in front passing between forelegs and under the
belly, finally tied around flanks in the rear.. For the purpose of impos-
ing the least feeling of restraint on ram, the apron was never fitted
very tight and thus the ram could easily mount the ewes in heat. The ram
was then led to one pen and allowed to check each ewe. Except Rambouillet
x Dorset Ho ned and Shropshire groups, ewes in any single pen d d not ex-
ceed 8 in number and the ram, therefore, had no limitation in contacting
each ewe. Regarding groups containing more ewes, the animals were either

taken out in the ad 3a cent yard or moved every now and then to facilitate
con act of both sexes. (Fig. II.)

As the work progressed, it was observed that the ram after surveying
a pen from one side to the other, stood is interested in ca se no ewe hap-
pened to be in heat. On the other hand, any ewe in heat was most immed-

iately detected and was removed frOIi the pen to induce the ran to attend

the rest. In this way, after checking all the pens one afte er tlze other,
the ram was separated and confined in his own pen till the next da .

From.May 11, 1951, the er es were gestured and shifted to the Kain
Barn. All the thee the ewes were given free access to and from the pas-
ture fields at will. Due to the onset of summer season, decrease in the
teasing activities of rams was noticed especially during hot parts of the
day. This necessitated a chang.e in checki Lng time as well as increase in

number of teasing rams to obtain reliable results. Consequently, two rams

-17-

instead of one were new used early morning instead of afternoon.

Ewes were generally found grazing and were driven back to the Barn
every day. They were then divided into 3 lots of approximately equal
sizes. One out of the three lots was confined at a time in a pen and rams
allowed to mix as before. Every ewe was identified from her ear tag num-
ber painted in bold letters on her back. Date as well as time of onset
and end of heat was recorded in each case in order to collect complete in-
formation of the sexual behaviour of individual ewes besides the flock as
a whole during the period under review.

Behaviour of Ram

Rams exhibited great variations in behaviour toward ewes. The same
ram behaved differently with the same ewes on different days, showing
more interest on one day and less on the other. However, no association
of such a varied behaviour could be established with the sen a1 activity
of ewes. On the other hand, disinterestedness of a ram after surveying
the whole lot of ewes was found to be a fairly reliable index of no ewe
being in heat in that lot. Twes attended least on the previous day were
in heat the following day while ewes in whom ram showed continued interest
for many da s did not come in heat for months after. Thus the rams were
never found consistent in giving more or less attention to females for a
considerable length of time.

Broadly Speaking, ram would go round practically every ewe in the
pen giving more attention to some and less to others till any ewe that
happened to be in heat was detected, otherwise he stood disinterested.
Immediately after contacting a ewe, the ram sniffed her vulva, elevated

his head with curled upper lip and sniffed air. The head was then low-

-18-

659w c
max one on» an wommdsvo_adm can Ava: mesa mo @5090

.N onsmfih

 

ered and same action repeated with the same ewe.‘ In others, after sniff—
ing vulva once, he walked to a second ewe without taking any further notice.
In still others, after having sniffed once or twice, regular teasing star-
ted which consisted of a variety of actions. Neck was stretched and head
moved up and down Leing in close contact with one side of ewe more often
with flank. At this sta. ge it appeared as if the ram is going to butt the
ewe. Along with head DOVements, tonguex was also mOVe d in and out of mouth
kept generally open. A typical murmuring sound was emitted at this stag
of action, sometime very low and often so loud that it could be heard from
a distance. Along with the actions mentioned above, raw would always
strike his fore leg against the belly or hind leg of the ewe while teasing.
A vigorous ran after sni ffir ng the vulva woulds raight away jump without
going through any of the above fcrzm1Wis. Such a behaviour was common
with young rams especi a.lly yecrlilg 8. On the other hand, aged rams did
not attempt to mount till they felt sure tha+ the ewe would not move.
Mfinity for certain ewes and antagonism against others was not observed
arhong rcrzns used in this echrlment.

Besides the characteristic beha iour of a ewe in heat, it seemed
probable that certain odoriferous substances were secreted during this
period that help the ram in locating such a ewe. To establish this,
vagina of Dorset Horned ewe No. 846 was swated on August 2, 1951 wit
cotton when she was in heat. The cot on swab was then rubbed ar und per-
inium of Southdown ewe No. 936 who was not in heat. The Southdown ewe
thus treated was then turned with another ran along with 4 other ewes.

The ran went around, sniffed vulva of each one of them and finally tart-

(0

ed teasing the Southdown ewe whose perinium had been smeared. The ewe did

-20-

not stand to teasing but in-spite of that, the ram attempted to mount her

several times.

It is further possible that such substances are secreted in varying
quantities and concent ations by individual ewes during heat.
substances persist for some time defending upon quantitiy and concentra-

tions secreted, which seems to be a suitable explanation as t why rams

5

jersistently follow only certain females for some"time after heat, when

5—,

such ewes do not stand to teasing.
Behaviour of Ewes.

Like rais, ewes too exhibited quite a variety of behaviours when a-
pproached by rams. 'Hhen in heat, they stood to teasing action of ram and
allowed mounting. At this stage it was very easy to catch the ewe for
identification of ear tag number which otherwise required considerable
effort.

Almost all whether in heat or not, stood to sniffing of vulva and
moved away when teasing started. there allowed teasing for some—time
and finally moved away. Still others jumped immediately when teased, then
turned back and started butting the ram. Most of the ewes that stood to
teasing urinated, wiggled their tails and moved away if teased any more.
A few individuals stood to teasing for any length of time but moved and
even jumped away when the ram attempted mounting. As in the case of rams,

individual ewes were found very inconsistent in their day to day behaviour

[’1
E.

and it was thu .possible to assign a set routine response to a certain
592718.19 0

Signs of Oestrus

-21-

A female is said to be in heat when she receives the male. Be-
haviour at this stage is very typical and can be detected easily even by
those who are not very well aware of it. They are restless, nervous and
wander in search of male if free to do so. Appetite is decreased, conges-
tion and even swelling of vulva is present with mucous discharge in some.
Bellowing and neighing is seen in cows and mares resyectively and the
tail is kept high. Frequent urination is very common but each time only
a small quantity of urine is passed. The writer has seen in young hei-
fers of Dhanni breed discharging actual blood when not mated. Ewes be-
have somewhat differently than females of other species of livestock men-
tioned above.

During this experiment, it was not usually possible in the absence
of ram to predict with a reasonable certainty that such and such ewe was
in heat. Congestion of vulva was observed in some cases while in others
it was not noticed. On the other hand in some ewes, vulva was found con-
gested in dioestrus and anoestrus periods.l Similarly mucous discharge was
not detected ingany case. This might have been either absent or in so
slight a quantity that it passed unnoticed. Growth of wool around vulva
and checking the flock only once a day might have been the other respons-
ible causes. Likewise nervousness, restlessness and bleating was not seen
in any ewe except one of Dorset Horned group No. 969 in one heat only. On
'this occasion, she was found standing apart from other mates and bleated
occasionally. When turned with ram she immediately walked towards him and
stood for mounting.

Symptoms of heat in the presence of ram may be summed up as follows.
As expected, the ram approached and sniffed vulva. Some of the ewes urin-

ated while others did not. Majority of them stretched their bodies and

-22-

brought rumps in close contact with the breast of ram. Nest of these
turned their heads towards ram every now and then and finally stood firm
when mounted.

Individuals were also observed wh did not always exhibit the char-

/

acteristic signs described above. They kept on movingthis or that way
while being teased and did neither stretch their bodies nor came in close
contact of the ram. 'When mounted they did not stand firm like the others .
Dorset Horned ewe No. 846 on one occasion on April 14, 1951 behaved this
way but stood firm like others next time.

A third group of ewes however, did not behave like either extremes
but took the middle course. To sum up, the ewes were extremely variable
with respect to the signs of oestrus. Even the same ewe was not always

found consistant in behaviour on successive occasions.

VISUAL OESLR AT CNS OF OZSTR 3 IN THE

E21

PERIHEETAL EUES FROM JANULQY 15 TO AUGUST 31

A total of 47 young ewes were observed daily from the start of the
experiment. During the course of this work that terminated on August 31,
few ewes died, some were removed and in two cases three were added to the
already existing number. In each breed group, dates of death, removal or
addition have been shown against the individuals so involved.

On account of shortage of pasture in August, it was decided to dis-
continue observing the ewes that had been in heat during August. Conseq-
uently a total of 15 such ewes (Dorset Horned 3, Harpshire 5, Oxford 1
and Ramb. x Dorset Horned 6) was removed from the flock. The ewes thus
removed have been indicated in their respective breed groups.

In order to present an overall picture of the sexual behaviour of
each ewe, a separate table for each breed has been prepared wherein the
record of each ewe presented for the entire period. Date of onset and end
of oestrus with respect to each ewe has been shown along with the dioes-
trus period and duration of heat.

Apart from such an individual treatment, a complete picture of each
breed group has been presented in Table II and Figure 3, showing the num-
ber of ewes observed and average percentages that came in hea in a cer-
tain month. In calculating these percentages, the number of ewes that
died,were sold, added or replaced, was counted in case they renained in
the flock for more than 15 days in that month, otherwise not.

It may be noted that the months during which none of the ewes was ob-
served in heat, have been omitted from the reSpective table.

Dorset norned Ewes

Only three ewes of this breed were available for observations through-
out the period (Table III). Out of these 3, two (Nos. 969 and E49) were
twins. None from the group came in heat during January, February, march,
Ihy'and June. The number that was observed in heat during April, July
and August was 2, 2, and 3 reSpectively.

Ewe. No. 846 was in heat on A ri1 14, for the first time and on July
16 and August 2. fir the second and third times respectively.

Ewe No. 969 one of the twins, came in heat for the first time on
April 9 and on July 6 and 22 for the second and third times respectively.
Fourth heat in this ewe was observed on August 8 when she was bred.

The last of this group was ewe he. N49 which came in heat on August
10 for the first time when she was also bred. These three ewes were re-
moved from the flock on August 13. It may be noted how different was the
behaviour of twin born ewes (No. 969 and N49) maintained under identical
environmental conditions.

Eampshire Ewes.

The number of ewes in this group was 7. Out of these, ewe No. 815
died on May 8 and No. 802 was slaughtered on February 22. Neither of the
two was observed in heat. From the remaining 5, ewe No. 819 was removed
from the flock on May 12 and brought back again on July 21. Another ewe
lo. 834 born on March 3, 1950 had still birth and was put in the flock on
May 12 (Table IV). however none of the ewes under observation, came in
heat during January, February, march, Kay and June. The number of ewes
found in heat during April, July and August was 1, 1 ;nd 5 respectively.

Ewe Me. 832 was the first to come in heat on April 29. For the second

time she was in heat on August 6.

-25-

First heat shown by ewe No. 816 was on July 24 and second on August

Ewes No. 819, 823 and 834 were in heat on August 7, 3 and 4 reSpect-
ively for the first time. The only ewe of this group that did not show
heat up to August 13 was No. 831. Uith the exception of this, all others
were removed from the flock on August 1°. The remaining ewe of this
group (No. 831) was observed up to August 31 and was not found in heat
till then.

Oxford Ewes.

Five ewes were ava lable in this group to start with. Out of these,
ewe No. 856 died on Kay 22 (Table V) without coming in heat till death.
From the remaining 4, no one was observed in heat during Januar', Feb-
ruary, may, June and July. The number of ewes that came in heat in March,
April and August was 2, l and 1 respectively.

Ewe No. 857 was in heat for the first time on March 2 but after that
she was not found in heat till August 31.

Ewe No. 867 was in heat on march 4 for the first time.on April 9 for
the second time. For the third time, she was in heat on August 8 and was
removed from the flock on August 13.

Out of the remaining three ewes (Nos. 854, 857 and 859), that were
observed up to August 31, not one was found in heat till then. The ewes
of this group that did not show even one heat during the entire period of
observation were Nos. 854 and 859.

Ramb. x Dorset Horned Ewes.

The number of ewes (8) in this group remained constant throughout the

period of observation. None came in heat during January, Narch and April.

-26-

The number that came in heat during February, May, June, July and August
was 1, 1, 2, 5 and 4 respectively (Table VI).

Ewe No. 346 was the first of her group that came in heat on February
25. The second heat observed in this ewe was on JUne 27 when she was
bred but she did not settle and was found in heat on July 14 and 31 for
the third and fourth times.

The second earliest heat from the group was shown by ewe No. 986 on
rhy'26 when she was also bred. Since hen, she did not repeat And was there-
fore, assumed to have been settled.

In addition to ewe No. 346 mentioned above, ewe No. 349 was second to
come in heat on June 9 for the first time and was likewise bred. She too,
did not come in heat after that and was therefore taken as settled.

Ewe No. 345 came in first heat on July 17 and again on August 4 for
the second tine. Similarly first heat in ewe No. 347 was observed on July
30.

First heat in ewes Ho.. 364 and 368 was found on July 4 and 2 resyec-
tively but neither of the two was seen in heat again till August 31.

Ewe No. 344 was the last to come in heat on August 4 for the first
time.

With the exception of ewes No. 364 and 368, all others were in heat
by August 13. From this date (August 13) onwa ds, ewes No. 364 and 368
were observed till August 31 and all the rest were removed from the flock.

Shropshire Ewes.

The number of ewes in this group was 16 at the onset. Out of these,

ewes Nos. 914, 917, and 937 died on July 22, July 2 and June 21 respect-

ively. From the remaining 13, ewe No. 908 and 936 were sold on August 8

(Table VII). None of these 5 ewes had been observed in heat by the time
of death or sale respectively. Out of the rest 11 ewes, no one came in heat
during January, February, March, May, June and July.

Ewe No. 929 wa= observed in heat on April 13 for the first time. Up
to August 31 she was not observed in heat for the second time.

Ewes Nos. 905, 923, 91111751 were found in heat for the first time on
August 19, 17, 17, and 16 reapectivelv. hone of these ewes were seen in
heat again up to August 31. The ewes that did not come in heat even once
till August 31 were Hos. 902, 912, 919, 931, 940 and 952.

Southdown Ewes.

This group consisted of 7 ewes to start with. Cut of these, ewe No.
963 was removed on April 8 without showing any heat till this date (Table
VIII). Out of the remaining 6 of the group, none came in heat up to July
31.

The first heat in this group, was shown by ewe No. 970 on August 23
with ewe No. 971 following on August 30. It is worth-while to state, that
these two ewes (N6. 970 and 971) were separated from the rest of the flock,
in the end of June and fed on concentrates and hay in order to be ready
for the show. The remaini-g 4 ewes of this group were on pasture alone
along with the rest of the flock and did not come in heat during the en-
tire period of observation even once.

Suffolk Ewes.

Only one ewe of this group was available to start with. On July 21,
two more yearling ewes of this breed were available and were consequently
added to the flock (Table IX). Up to July 31, none of the 3 was observed

in heat.

-23-

On August 19, ewe No. 932 was observed in heat while 891 and 893 did

not come in oestrus till August 31.

-29-

DU? AT ION- ? OESTRUS
The flock was checked once every day up to August 12, when twice a
day checking was decided with the idea, that some ewes might have been in
heat that passed u noticed on account of exceptionally short duration. So

in addition to the morning, evening checking was also started from that

Duration of oestrus was calculated from the time, when a ewe was
first observed in heat to the time when she was first found to be out of
heat at the checking time. A ewe was considered in heat when she stood
to mounting by the ram, and out of heat when the ram was not allowed to
mount. Calculated this way, the duration of heat that exceeded 24 or 48
hours has been shown with / sign, and in case of less than 24 with - sign
up to August 11. From August 12 onwards, it was possible to split the -
24 hour's duration into ~12 and /12 hours.& likewise the #21 hour's dur-
ation into —36 and [36 hours.

Out of the hserved oestrus periods between August 12 and 31, the
writer did not find any individual with -12 and /48 hour's duration. It
may be noted, that the data recorded in connection with the duration of
oestrus, does not furnish the required accuracy. It is possible, that a
ewe found to be in heat at 8 A.M. on a certain da , might have been in
heat from the last 23 hours. On the other hand, it is equally possible,
that a ewe might have been in heat just a short while before the checking
time. A similar discrepancy, might have been operating regarding the end
of oestrus. As such, in the analysis of this data it was assumed, that

the onset as well as end of oestrus was according to the checking times.

f:

-30-

Duration of Oestrus in the Different Breed Groups

In all, 38 oestrual periods were observed among the different breed
groups (Dorset Horned 8, Hampshirei7, Oxford 4, Ramb. x Dorset Horned 12,
Shropshire 5, Southdoxm 1 and Suffolk 1) which ranged from ,112 to #48
hours in duration. Out of tiese, 9 or 23.68% were found to be of -24, 26
or 68.42% of %24 and 3 or 7.89% of [48 hour's duration (Table X).

From the 9 oestrual periods of ~24 hour's duration, 3 were observed
in the ShrOpshire, 2 and 2 among the Dorset Horned and Hampshire and 1 and
1 among the Oxford and Ramb. x Dorset Horned groups respectively. It may
be noted that the largest number of -24 hours duration occurred in the
Shropshire ewes.

On the other hand, out of the 3 periods of #48 hours length, 2 were
seen among the Hampshire ewes and one among the Rama. x Dorset Horned ewes.

Further analysis of the data revealed that even the individual ewes
were not consistent regarding the duration of heat at different times.

Ewe No. 816 of the Hampshire group Table IV) had /24 hours duration on

the first oestrus in July and #48 hours on the second in August. Similar-
ly ewe No. 832 of this group had /24 hour's duration on the first oesturs
in April and -24 hour's duration on the second in August.

The only oestrus of /48 hours duration in the Ramb. x Dorset Horned
group was seen in ewe No. 346 (Table VI) on the first oestrus in February.
During the remaining three oestrual periods seen in this ewe, the duration
was /24 hours in each case.

Likewise, two ewes No. 846 and 969 of the Dorset Horned group (Table
III) had -24 hours duration in April when heat was observed in them for the

first time. Later in July and August, 2 oestrual periods were observed in

-31-

ewe.No. 846 and 3 in ewe No. 969 which were of /24 hour's duration.

The duration of oestrual periods, most frequently not with among all
the groups and individual ewes, was /24 hours with the exception of the
SZrOjshire group, in which only 2 out of 5 such periods were of /24 hours.
The fact that only one heat period was observed in e,ch ewe of the Shrop-
shire group might not have given the true picture cepccially when inconsis-
tency in the individual ewes occurring so frequently was taken into con-
sideration.

Only 3 oestrual periods of‘/ 24 hours duration, were observed after
August 12, which con :3. be Splitted into -36 and /36 hours. One out of
these 3, was of -36 hours duration seen in Shropshire ewe No. 311 and the
other two were of /36 hours duration, one in Southdown ewe No. 970 and the
other in Suffolk e.e No. 892 (Table VII, VIII and IX). However, it seemed
reasonable to conclude that, the duratian of oestrus in these ewes was K24
in the great majority of cases irrespective of i.dividual as well as

breed differences.

-32-

DIODSTRUS PniIGD

Dioestrus period may be defined as a period of sexual quiescence be-
tween heat periods.

Length of the dioestrus period was counted from the day when a ewe
did not allow the ram to mount immediately after oestrus to the day when
she stood for mounting again, both days exclusive. A total of 13 such
periods was observed whichsranged from 118 to 12 days (Table II).

Dorset Horned ewes No. 846 and 869 were observed in heat for the
first time on A ril l4 and 9 respectively. For the second time, these ewes
were found in heat on July 16 and 6 after a long period of sexual inact-
ivity of 91 and 86 davs respectively. Third heat in these ewes was obser-
ved on August 2 and July 22 after a dioestrus period of l4 and 13 days in
each case. Ewe No. 969 was again found in heat on August 8 after 14 days
interval. It was thus evident that ewes of this breed, underwent a period
of sexual rest after showing only one oestrus in April to ahout the end of
first week of July, when they started coming in heat refiularly (Table III).

Hampshire ewes No. 816 and 832 were found in heat for the first time
on July 24 and April 29 respectively. For the second time, ewe No. 816
was found in heat on August 8, after a dioestrus period of 12 days. On
the other hand e'e N0. 832, went through a period of long rest of 96 days
and was in heat for the second time on August 6. Out of the remaining 4
ewes of this group, 3 came in heat in August for the first time. As all
of these ewes were removed from the flock on August 13, it was therefore,
not possible to note their ‘ture so; 31 behaviour. (Table IV).

Two dioestrus periods observed in the Oxford group were in ewe H0.

867. She was first observed in heat on “arch 4 and again on A ril 9 after

33 days. For the third time, she was found in heat on August 8, after
observing one of the longest periods of sexual inactivity of 118 days (
Table V).

Four dioestrus periods observed in the Ramb. Dorset Horned group,
were in 2 ewes No. 345 and 346. First oestrus in ewe No. 345 was seen on
July 17 and second on August 4 after a dioestrus period of 15 days. Ewe
No. 346 was the first to come in heat on February 25 and again on June 27
after a dioestrus period of 118 days, the second longest duration. Third
and fourth heats in this ewe were found on July 14 and 31 respectively,
with a dioestrus period of 14 days in each case. Like Dorset Horned ewes ,
this group too (Ramb. x Dorset Horned), went through a period of sexual in—
activity up to about the end of May (Table VI).

Leaving the long periods of sexual inactivity aside, the longest and
shortest durations observed were 15 and 12 days respectively. Out of the
7 such periods, the duration was 15 days in one case, 14 days in 4 and 13
and 12 in one case each respectively with a mean of 13.71 and stanfard
deviation of éO.7 days.

Within the breed groups, the duration tus 14 days in 2 cases and 13
days in 1 case in the Dorset Horned group, 12 days in the Hampshire and
15 days in 1 and 14 days in 2 cases in the Ramb. x Dorset Horned group.
Thus the longest duration was observed in the Ramb. x Dorset Horned group

and shortest in the Hampshire group.

-34,

OBSTR 3 CYCLE

Oestrus cycle may be defined as the interval between the onset of the
preceding and succeeding oestrus. This was counted from the day a ewe was
observed in heat to the day when she was again found in heat, including
the former and excluding the latter.

Out of a total of 13 such cycles observed, the duration ranged from
122 to 15 days (Table XII). In seasonally polyoestrus females as ewes,
an unusual cycle length of 122,99,9_3 and 88 days is an indication of sex-
ual quiescence during that period. Leaving such durations aside the in—
terval was 18 to 15 days. The two extreses of’interval were observed in
the Ramb. x Dorset Horned ewe No. 345 and Hampshire ewe No. 816 respect-
ively. A majority of the oestrual cycles, a total of 4 out of 7, were of
17 days duration with a mean of 16.71 and standa d deviation of £9.7 days.

In case of the Oxford ewe Re. 867, the interval betw en the first
and second oestrus cycle was 36 days. This showed that this ewe missed
one cycle which falls within the mean cycle length. It is equally poss-
ible that she might have exhibited an exceptionally short oestrual period
this time that passed unnoticed in once a day checking that was being

followed at that time.

-35-

ONSET OF THE BETH“IHG SEASON

The number of ewes of each breed group that was observed and the per-
centages that came in heat every month from the different groups ave been
shown in Table II and Figure 3. Breeding season in sheep, is the period
when majority of the ewes accept the males, and in case they are not
mated, or those who do not settle after mating, k~ep on coming in heat
throughout that period with a reasonable regularity. However, variations
in oestrual cycle length, as early or late oestrus or missing of one heat
etc. are met with even in the regular breeding season. Sucn variations
are due to hereditary, breed and environmental differences, some of which
are difficult to control and evaluate. The data given in Table II and
from Te les III to IX are being interpreted in this light in the discuss-
ion that follows.

The Dorset Horned ewes underwent a period of sexu quiescence from
January up to the end of Harsh. In pril,2 out of a total of 3 observed
or 66.66% were found in heat. Both these ewes after showing only one oes-
trus each, again observed a period of sexual rest up to the end of June.
In July, the same two ewes (No. 969 and 846) can in heat and from then on-
wards, both kept on coming in heat after a dioestrus period of 13 to 14
days up to August 13. The remaining ewe of the group (No. {49), was also
found in heat in August, thus giving a percentage of 66.66 and 100.00 in
July and August respectively. It was therefore, concluded that the breed-
ing season in the Dorset Horned ewes started in the first week of July,
and by the first week of August, all of them were in heat.

The Hampshire ewes similarly went through a period of sexual inact-

ivity, from January through March. In April, 1 (Ho. 832) out of the 6 or

-36—

16.66% of the total was found in heat. During hay and June, none was
found in heat but in July, 1 (No. 816) out of the 5 or 205 of the ewes ob-
served, was found in heat. In August, 6 ewes of this group were otserved
of which 5 or 83.33% were found in heat. Ewe No. 8 6 which was found in
heat on July 24 was one of the 5 ewes that came in heat in August, after
a dioestrus period of 12 days. None of the ewes, that were in heat during
August, could be observed for the second oestrus on account of their re-
moval from the flock on August 13. In view of the fact, that 5 out of the
6 observed came in heat during August and the one found in heat during
July repeated after a normal dioestrus period, it was inferred that the
breeding season in this group began, be ween the last week of July and the
first week of August. Comparing this group with the Dorset Horned, the
onset of the breeding season was delayed for about 3 weeks.

The 5 ewes of Oxford group remained sexually quiescent during Jan-
uary and February. In March, 2 of them (No. 857 and 867) or 40% of the
total were found in heat. In April, ewe No. 867 was again found in heat
after a dioestrus period of 33 days. During May, June and July, none was
observed in heat but in August, 1 (No. 867) out of a total of 4 or 25.0%
was seen in heat, after a dioestrus period of 118 days. This ewe was re-
moved from the flock on August 13, and as such, it was not possible to ob-
serve her future sexual behaviour. The rest 3 of the group were observed
till August 31, but none was found in he t. In view of the absence of
further observations on the only ewe that came in heat in August, and the
sexually quiet behaviour of the rest, the only conclusion that could be
drawn was, t.at the bree.ing seas:n in this Ireed did not set in until the

end of August.

-37-

Out of the 8 ewes of Ramb. x Dorset Horned group, none came in heat
during January. In February, 1 (H0. 346) or 12. % of the total was found
in heat. In March and A ril, no heat was observed in this group but in
May, again 1 (No. 986) or 12. % of the total was found in heat. Thi5"‘
~ewe was trod. In June, 2 out of the remaining 7 (No. 346 and 349), or a
total of 28.57% was found in heat. Both these ewes were also bred but ewe
No. 346 did not settle and started coming in heat regularly thereafter,
observing a dioestrus period of 14 days each time.

In July, out of a total of 6 ewes observed, 5 or 83.33% were found in
heat. On August 13, 6 ewes of this group were removed from the flock which
consisted of 2 ewes that had settled and 4 that came in heat during August.
The remaining 2 ewes (No-364 and 368) were observed till August 31, but
they did not come in heat till then. Thus out of a total of 6 ewes obser-
ved during August, 4 or 66.66% were found in heat. Leaving the 2 ewes that
were bred and settled during the end of Hay and beginning of June, the
first oestrus that was followed by the regularly recurring heat periods in
that very ewe and in maiority of the rest was observed on June 27. Based
upon the evidence of theaedata, the breeding season in this group started
betwcen the last week of June and first week of July, falling in line with
the Dorset Horned ewes and about a month earlier than the Hampshire group.
The Shropshire ewes remained sexually inactive from January through March.
In April, 1 (No.929) out of the 16 ewes or a total of 6.25% was found in
heat. This ewe was not found in heat again up to August 31. From May
through July, the group was again sexually silent. Four of the 11 ewes
observed or a total of 36.36% were found in heat on August 16, 17, 17 and

19. None of these ewes was found in heat up to August 31, which was

natural with a mean dioestrus period of 13.71 days observed in the entire
flock. The data so compiled showed, that the breeding season in this group,
started after the middle of August, a month and a half later than the Dorset
Horned and Ramb. x Dorset Horned groups and about two weeks later than the
Hampshire group.

The group of Southiown ewes was one of the two that observed the
longest period of sexual quiescence from January through July. Two ewes
(No. 970 and 971) out of the 6 observed in August, or a total of 33.33%
was found in heat in the last week. The rest 4 did not come in heat up to
the end of this month. As already mentioned, these 2 ewes were being fed
on concentrates and hay from the end of June as compared with the remain-
ing 4 which were on pasture. As such, these two ewes were in a much better
bodily condition than the others. Better feeding might possibly have been
the cause of early heat in them alone. iowever, assuming that the other
ewes of this group would have been found in heat after a reasonable inter-
val in case observations had continued after August 31, the breeding sea-
son in that case start d in the last week of August, about 7 weeks later
than the Dorset Horned and Ramb. x Dorset Horned groups, 3 weeks later
than the Hampshire and one week later than the Shropshire group.

In the Suffolk group only one ewe was under observation till July 21,
when 2 more were available. Up to July 31, no oestrus was recorded in
this group which constituted the other longest period of sexual inactivity
in the second group.

In August, 1 out of the 3 ewes, or a total of 33.33% was found in
heat. The other 2 remained sexually quiet till August 31. with such a

meager data at hand no definite conclusion could be drawn regarding the on-

set of the breeding season in this group. However, assuming that from
August 31 onwards, the group would start coming in heat regularly, the
breeding season in that case started 7 weeks later than the Dorset Horned
and Ramb. x Dorset Horned groups, 3 weeks after the Hampshire and one week

after the Shropshire group.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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m. o o m. o 0 mo 00 m: o o W? 0 0 mo 00 m... cm... 0
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HH mafia

 

TABLE III

‘8 FROM JANUARX 15 TO AUGUST 31.

."I'
Hi)

1‘ T HORNED 13'

(1‘1
.1

THUS IN DOI

OBS

T4"
.

OCCURRENCE O

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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(sanoq) ~¢ I 3&23
uotqexuq {E Six“
P:
3 (819p) to I to \2‘
pug r1 (v
(8129)
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potJea I l I
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(men) I . a
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PUH
(849p)
Issue :1 ' °‘
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a: 2: a) 2: cs
PI oz aw

 

 

 

 

TABLE IV

’ OCCURRENCE OF OESTRUS IN HAMPSHIRE EWES FROM JANUARY 15 TO AUGUST 31.

 

 

 

 

 

 

13 53
'§§3 a: “x E?
£35“ *‘ '8
.s :5 130 13
gas I, I.. 3
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snaqseotq PI . ex
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July

 

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April

”58
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5/1 24

 

 

(a..p)
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29

 

8
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6
2:

802

815

816

819
823

831

832

834

 

 

 

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V

TABLE

OF OESTRUS IN OXFORD EWES FROM JANUARY 15 TO AUGUST 31.

”I?
4.4

OCCURREHC

 

Died way 22

 

spotieg
{snadseo

I910;

3

 

 

(sfisp) potaeg
snaiseotq

 

(sanoq)
uorqeanq

24 118

 

August

a e
‘ 1.5g,

9

 

(91??)
Issue

8

 

 

(sfiep) potaeg
snaqseotq

33

 

April

(sxnoq)
notaeauq

 

(848p)
PUH

 

(949p)
aesuo

9 111 V24

 

 

March

Nausea

 

(sxnoq)
wordslnq

 

ma

4 /24

6 V24

 

 

(819p)
qesuo

2

4

 

 

a) o
3 o
HZ

854

856

857

859
867

 

 

 

'OH IBIJ98

 

 

 

 

 

 

 

 

 

TABLE VI

UARY 15 TO AUGUST 31.

~Iv
V

M J}

'HES FRO

,_
H
1.1

OCCURRENCE OF OESTRUS IN RAMBOUILLET X DORSET HORNED

.45-

 

Sporaeg
Isnaqseo {940;

2

br
ed

 

(358p) potqeg
anissorq

 

(sqnoq)
uotqsduq

~24

 

August

(919p) pus

 

(seep) qesuo

4 5

4 6 /24 15

 

sfie orae
( ghagséotg

 

(ssnoq)
uorqeanq

#24

 

July

(9499) pus

19 #24I

6 #24

 

(eqep) aesuo

17

30 8/1

4

 

(sfiep) potdeg
snaqseotq

 

(saneq)
uotdean

 

June

(819p) pug

 

(848p) aesuo

 

(sflip) poised,
anaseotq

1 6 1
- 27 29 /24 118 3% 8}; iii 12 - - -

 

(sanoq)
notiean

 

Hay

(819p) put;

 

(819p) aesuo

26 28 #24

 

February

(sfisp) poraeg
snaiseotq

 

(sanoq)
uorqeanq

 

(9191)) ms

 

 

(849p)
aesuo

25 28 /48

 

Q).
30
LIJZ

344

 

 

 

'ON IBIJGS

 

 

 

2 345
3 346
4 347
5 349
6 364
7 368

 

 

 

 

 

 

8 986 ”

 

 

 

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4.“ NH\ mH S I I I I mmmo

I I I I .. I I I I as .0
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I I I .. I I I I ..mHe 0

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HH> e

4
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TABLE VIII

OF OESTRUS IN SOUTHDOWN EWES FROM JANUARY 15 TO AUGUST 31.

I?
.....I

OCCURRENC

-47-

 

Removed April 8

Removed Aug. 30

 

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(eqep)
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23
30

 

 

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963

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972

978

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-52-

0113 BUS IN 13.313 LAME

Like other phases of sheep industry, occurrence of first oestrus with
respect to age in ewe lambs have been studied by workersikom time to time.

HcKenzie and Phillips (1930), found that out of seven Yampsh re ewe
lambs born between February 7 and Iareh 21, 1930, all had been in oestrus
by October 19, 1930, at an a*. age of 213 days (range 187 - 250 days).
Out of another group of 13 Shropshires, eight came in heat by November 4,
1930. These were born in February and early Harsh of the same year. The
remaining five born on.Kar:h 2, 10, 17 22 and 31 did not come in heat by
Noveuber 4. He concluded that puberty in early ewe lambs is reached in
the F111 months; later lambs may fail to come in oestrus until the follow—

ing year.

i

(

Cole and Miller (1935) found That in eight ewe lambs the first oes-
trus was expressed at eight to 10 months age. They further stated that
the first oestrus of the breeding season appeared later in ewe lambs than
in mature ewes.

Roux (1936) found that first oestrus in Merino ewe lambs occurred
when they were 16 to 20 months of age.

By January 15, 1951, vhen this experiment was started, the breeding
season had already passed and it was therefore not possible to subject the
ewe lambs to direct observations for this specifi phase of study. The
fact that ewes rad never been bred at the College until about 1% years of
age, made it more difficult to obtain precise information as no data were
available for the previous years. It was however, noticed in the breeding
records the some ewe lambs of Hampshire, foord and Shropshire breeds

lambed in 1948 and 1951 lambing seasons. These ewe lambs were bred per

chance while on pasture bys ome rams who gained access s mehow, inspite of
the existing arrangements for keeping them separate. Lambing records of

22 such ewes were available regarding whom the data are presented in Table
XIII. Breeding dates of these individuals were calcm ated from their res-
pective lambing dates with an average gestati n period of 147 days. Re-
cords of the dates of Mir h of these ew s were available which enabled cal-
culation of the breeding ages reSpectively. It is probable as well that
some of these ewes might have been in heat on one or more occasions before
they were bred. However, the data falls in close comparison with the
findings of other workers refered to above.

In this case, the average age of the onset of oestrus in Hampshire
group was 257 days ranging between ;35 to 268 days. In Oxford r cup, L53
Iays was the average age and ranged between 240 to 272 days. astly in
Shropshire ewe lambs, the observed range was from 231 to 297 with an av-

erage of 257 days. Considering the three groups together, the average age
was 256 d ays ranging between 231 and 297 days.

Comparison between ages at the breeding true among Hamps -ire ewe la-
mbs in this case and at first oestrus of those reported by HcKenzie and
Phillips in 1930 showed that the oestrus appeared 44 'ays later in the ewe
lambs at this sta+i:n. In the absence of direct observati ns it appears
safe to assume that this delay might have been due to the absence of ob-
servations rather than clima tic, nutritional or strain differences. 0n
the other hand average age of oestrus among all g rougs observed here was
almost the same, 257, 255 and 257 days in Hampshire, 0::ford and Shropshire
breed 3 respectively.

It 2y thus be concluded that ewe lambs of the above three breeds can

be bred at an average a; e of 255 d ays.

TABLE XII I

AGE OF III-I73 Iii-BS AT TIE E32331 IIIG TEE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5 SW8 4 '3 “add *3 2° 42%-
8 ‘1‘ IS" 23 83388 23" a 22:0
1 303 Hampshire liar. 9/47 Dec. 1/47 Apr. 26/48 8/21
2 311 " Mar. 15/47 Dec. 2/47 Izpr. 27/48 8/17
3 313 n Mar. 1.6/47 Nov. 25/47 Apr. 20/48 8/9
4 322 " 1m. 29/47 Dec. 22/47 Loy. 17/48 8/23
5 809 " Feb. 23/50 Nov. 18/50 Apr. 13/51 8/26
6 810 " Feb. 24/50 Nov. 21/50 Apr. 16/51 8/28
7 834 n Mar. 19/50 Nov. 13/50 Apr. 8/51 7/25
8 354 Oxford Mar. 29/47 Dec. 30/47 May. 26/48 9/2
9 362 " Apr. 3/47 Dec. 3/47 Apr. 28/48 8/0
10 372 " Apr. 12/47 Dec. 26/47 May. 21/48 8/14 _
11 861 n Mar. 9/50 002.2959 43.25/51 8/21
12 862 " Mar. 9/50 N;ov.1o5/50 ammo/51 8/6
13 202 Shropshire Mar. 3/47 Dec. 4/47 Apr. 29/48 9/1
14 206 " Mar. 8/47 Jan. 4/48 r-on. 30/48 9/27
15 215 " Mar. 18/47 Nov. 28/47 Apr. 23/48 8/10
16 223 " Mar. 3/47 Dec. 4/47 Apr. 29/48 9/1
17 232 " Apr. 5/47 Nov. 26/47 Apr. 21/48 7/21
18 250 " May. 3/47 Dec. 25/47 Ma . 20/48 7/22
19 903 " Feb. 18/50 Nov. 10/50 Apr. 5/51 8/23
20 916 n Mar. 9/50 Nov. 30/50 Apr. 25151 8/22
21 924 *1 Mar. 5/50 Nov. 11/50 Apr. 6/51 .3/6
22 927 " Mar. 7/50 Nov. 13/50 Apr. 8/51 8/6

 

 

 

 

 

 

 

 

 

-55-

SEXUAL IZHAVIOUR IN THE BREEDING SLASON

According to their sexual behaviours, females of different species
of livestock have been classified as monooestrus, seasonally polyoestrus
and polyoestrus.

Cows come in heat at usually regular intervals of about three week
all the year round and are therefore classed as polyoestrus.

flares and ewes, on the other hand come in heat after every three
weeks and 16 to 18 dais respectively in certain seasons of the year and
are claSsel as seasonally polyoestrus.

Commencement of the breeding season is marked when a reasonably re-
presentative number of females of‘a certain species start coming in heat
regularly. Similarly breeding season is said to have passed when majority
of the females of that Species quit coming in heat. In some species of
animals as deer, the males also go through a period of sexual inactivity
for some part of the year.

Eith the object of knowing the frequency with which ewes of the same,
as well as different bro ds mated in the different years at the Michigan
State College, the data were obtained from the records of the College breed—
ing flock from 1948 to 1951.

In seasonally polyoestrus females as sheep, the choice of early or
late breeding lies with the flock owner. Consequently some breeders pre-
fer breeding thvir flocks earlier than others. At this station the rams
Y9T9 turned in on September 20 in 1948 and 1949 and September 29 and Oct-
ober 2 in 1950. They were allowed to run with ewes till January 31 each

year and separated thereafter as detailed in Table XIV.

 

 

 

 

 

 

 

 

 

 

—- - - —--—-—¢
, 1948 - 1949 1950
B‘ 99d In Out In Out In Out
Hampshire Sept. 20 Jan. 31 Sept. 20 Jan. 31 Oct. 2 Jan.31
Oxford 1: n n n Sept . 29 u
_.._.4‘
Shropshire u u u u n n
Southdown n n n n u u
Suffolk n n n u n n

 

 

 

 

 

 

 

 

 

Breeding dates of individual ewes were calculated from the lambing
dates with a gestation period of 147 days in each case.

Obviously it was difficult to determine the precise dates for the
onset of the breeding season in different breeds beyond the dates of turn-
ing in the rams. It was equally difficult to know for sure whether the
late breeding ewes were habitual late breeders or not for the above rea-
son. Partial or complete infertility of some rams in the early season
might have been one of the most important factors, at-least in some ewes
that brei late in those seasons. In order to eliminate this factor, fur-

ther investigati ns r

(D
U»?
"3

a ding fertility of rams at the time they were tur-
ned in revealed, that Shropshire ram No. 575 (BUTTER) pruchased in Sumner
1949 and used as ram lamb in the following Fall was not completely fertile;
for at least sometime in the beginning. Similarly another Shropshire ram
404 (CCC) was also infertile in the start of the hreeiing season of 948.
Likewise semen of Hampshire ram No. 4-50 (BECKY) was of poor quality in

1950 breeding season. .

a57-

Number and Percenta ges ofE es Settled

The data were further arranged in Tables XV to XIX according to num-
ber and percentages of ewes of the same breed that settled in different
months. Besides this, Figures 4 to 10 inclusive present graphs sh wing
the Percentare of ewes of the same as well as different breeds that se-

tlel in different months of the same as vell as different breeding sea-

sons.

A careful study of the tables as well as graphs revealed that out of

mpshire ew 5, 34.78, 69.56 and 81.48 yer cent settled in October 1950,

1949 and 1948 respectively. During 1950 breeding season, 52.17 per cent
of the ewes, the peak figure were settled in Nevenber. Hampshire ram
1a:1b No. 4-50 (ShC OLI) used this syear was only parti ally fertile in the
early season and thus some out of 23 ewes in mating did not settle during
October (Table xv).

Th percentages of Oxford ewes that settled during October 1950,
1949 andl M4 was 73. 33, 78. 6 and 94.44 resrectively. During 1950 and
1949, 13.33 and 14.28 per cent settled in September but none during 1948.
Th-s year 5.55 per cent settled in NOVUHbBr (Table XVI). It seemed that
either the breeding season started later in 19 48 or the ewes that came in
heat during September were in dioestrus periods between Septeneer 20 when
the ran was turned in and October 8 when the first ewe of the group (No
425) settled. With a dioestrus period of 155days it was evident that ewe
No. 425 alone might have been in heat just before the ram was turned in as

all others fell beyond the normal dioestrus period. It therefore appeared

reasonable to assume that onset of the breeding season was late in 1948.

Nutritional and ph,:icd factors might have been responsible but to evalu—

 

ate these was impossible for practical purposes.

The Shropshire group also showed height of breeiing activity dur-
ing October when 78.05, 75.75 and 71.74 per cent of the ewes settled in
1950, 1949 and 1948 respectively. During 1950 and 1949, 4.88 and 15.15

1- , A
0301108 01

per cent of the ewes settled in Septembertut none in 1948. A
any settled in September was most probably due to ram No. 404 (000) who
was partially infertile in the early season of 1948. As such late breed—
ing in this case might have been due to infertility of the ram (Table
XVII ).

Likewise, height of conception rate among Southdown ewes also 0-
ccurred in October reaching 70.4, 64,7 and 50.0 per cent in 1950, 1949
and 1948 respectively. It was rather interesting to note that in 1950
and 1949 none settled in Septem er, December and January. In 1948 how-
ever, 25 per cent settled in Septem er while 8.33 per cent in December
and January eae . Out of the three ewes that settled in September, tw
(he. 87-40 and 331) did not appear in the flock during the following years
but the third (No. 63) that settled in January 1948 was settled in Novem-
ber and October during 1949 and 1950. Nutritional and other such causes
in tLis case and resulted in late breeding (Table XVIII).

seemed operatin

Regarding Suffolk ewes, the data were available only for 1950 and
1949 breeding seasons. Mereover, the total number of ewes in the flock
was only four each y ar. However, in 1950 all of them settled in October
but in 1949, 75 per cent settled in September and 25 per cent in October.
The four ewes that appeared in 1949 were purchased from outside and were

alrea y bred. Breeding records for 1950 revealed that these ewes settled

from October 2 to 8. Probably these ewes might have been in heat during

-59-

September and would have settled in case the ram was available eariler
(Table XIX).

From the above discussion it appeared that partial infertility of
some rams, breed and individual variations among the ewes and finally nu-
tritional and other such environmental difference were respcnsible for
variations among the percentages of ewes settling in different months dur-
ing the p riod under review. In spite of the above factors which were hard
toeevaluate and control, the percentage of settled ewes was low in Sep-
tember and highest in October, going down in November and December each
year. January marked the close of breeding season every year when a very

low percentage of ewes was found settled.

-60-

 

 

 

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DISCUSSION
Duration of Oestrus

In the entire flock of ewes under observation, 38 oestrual periods
were observed up to August 31. In 9 such periods, the duration was found
to be -24, while it was #24 and /48 hours in 26 and 3 out of the ramain-
ing 29 periods. It was thus evident, that the duration of /24 hours was
most frequent in the whole flock.

In eaeh breed group, the duration of /24 hours was again more fre-
quent e: :cept in the Shr Ops.ire group, in which, out of a total of 8 oestr-
ual periods, 6 were of -24 hour's duration.

It may be noted that Table X shows only 3 oestrual periods of —24
hour's duration instead of 6. Th ne writer continued observing the flock
even after August 31, with the idea to collect if possible, some addition—
al in:ornwatin that might help in a more efficient interpnetation of the
results. Out of the 6 periods of -24 hour's duration, 3 were observed in
ewes I0. 951, 91‘9em1902 between September 1 and 2. Ewe No. 951 on a
previous heat on August 16 had also -24 hour's duration. It was thus evi-

.ent that the duration of heat was shorter in the Shropshire ewes as com-
pared with the rest.

Only 3 periods of /Zt8 h urs were o.scr«ea, 2 in the Hanoshire and l
in Ranb. x Dorset Horned ewes. The duration of /48 was observed on one
oestrus only in each case.

Similar worlc reportei by McKenzie and Philli13s (1930) showed tha at out
of 247 oestrual periods, 74% were of 18 - 36 and 3% less than 9 or more

han 48 hours in length. They further observed that the mean.duration in

the Hamps hi ire, Shropshire and Southdown breeds was 30.7, 26. 7 and 24.0

-73-

hours respectively, the Hampshire ewes therefore, had longer oestrus than
the other two breeds.

Terril (1935) observed 884 heat periods that ranged from 5 - 72 hours
in length. He found the mean duration of 30.7 in the IIamf shire ewes as
compared with 26 hours in the Shropsiire and Southdown groups. In this
case too, the duration of heat was longer in the Hampshire ewes.

McKenzie and Terril (1937) presented data on 1235 oestrual periods
of Hampshire, Shropshire, Southdown, High Grade Rambouillet and Grade Ham-
pshire and Shropshire ewes. The duration'in this case ranged between 3
and 73 hours with a mean of 29. 33. Periods of less than 24 hour's dura-
tion were met with in every group, 18.2% fell below 21 hours and 15.5 p a-
bove 39. About 7.5% of the periods were less than 15 and 78 above 45
hours in duration. In the two groups of Southdown ewes, the mean duration
was 23 and 26.4 hours and in 2 of the Shropshires, it was 24.2 and 28.2
hours respectively. In 3 groups of Hampshire ewes, the mean duration
ranged from 28.6 to 31.3 hours. The longest mean duration was observed
in Grade Hampshire x Shropshire ewes and s.ortest in the Grade Rambouillet
ewes.

Kelly and Shaw (1939) reported, that out of 1 group of Dorset Horned
and 2 of Merino ewes, the duration of oestrus was longer in the former than
the latter. Moreover /24 hour's lengths were more common in the Dorset
Horned ewes as compared with the Merinos, whose majority had ~24 hour‘s
length.

Comparing the results of the present investiga ti ion w;Lth that of other
workers, 23.68% of the oestrus l per ods were of -24, 68. 42% of K24 and 7.59%

of #48 hour's length. As the durations of such periods were grouped by

-74-

every worker in a different way, it was therefore difficult to make a fair
comparison. McKenzie and Phillips (1930) observed 74% of the periods be-
tween 18 - 36 hours in duration which was a close comparison with 68. “%
grouped under #24 hours in the present experiment. They had only 3% cases,
in which the observed length was —9 or #48 hours. this case 7.8 % fell
in 48 hour's duration, while no comparison was available for -9 hour's
length.

Regarding the length of oestrus in different breeds, the above work-
ers found that the Hampshire ewes had longer durations than the Shropshire,
Southdown and Grade Rambouillet ewes. The same results were secured in
this experiment, when out of the 3 periods of /48 hour's duration, 2 were
found in the Hampshire group as compared to only one in the rest of the
ewes of all groups. In the Dorset Horned ewes likewise, more durations of
/24 hours were seen than -24 hours as reported by Kelly and Shaw (1939).

To summarize, the duration of oestrus ranged from /12 to K48 hours
but in the majority of ewes except Shropshires, it was /24 hours. Length

of oestrus in the individual ewes varied in some cases at different heat

3

Jeriods, being less in some and more in the other than the preceeding or

I-r

succeeding oestrus and vice versa. Such variations might have been the re—
sult of eXperimental error, environmental differences or physiological state
of the ewes.
Oestrus Cycle
Out of 116 cycles observed by thenzie and Phillips (1930), 92 were
14, 15 and 16 days in duration. The over all average was 16.6 with a
range of 8 to 49 days. The average cycle length in ewe lambs was 15.9

.1

CL 3:); S o

-75-

Terril (1935) found, that the duration of oestrus cycle varied from
14 to 19 days in 590 cycles. The mean cycle length in this case was 16.5
days.

From a total of 1038 cycles observed by HcHenzie and Terril (1937),
938 were found within a range of 14 to 19 days with a mean of 16.72 days.

Kelly and Shaw (1937) reported, that in the majority of oestrus
cycles, the observed length was 15 to 19 days and from.these cycles, the
duration of 16 - 18 days was the commonest.

Similarly, Smith and Singh (1937) found, that in Bihancr ewes, the
cycle length was 15 to 19 days.

The writer, during the conduct of this work observed an interval of
15 — 18 days with a mean of 16.71 days which was almost equal to the in-
terval as well as mean lengths observed by the above workers. It was in-
teresting that in the Indian ewes, the same cycle length was observed as
in case of ewes of the European origin. However the Indian ewes were breed—
ing twice a year.

Onset of the Breeding Season

The data collected from the observations in this exoeriment showed,
that 66.66% of the Dorset-Horned, 16.66 of Hampshire and 6.25% of the Shrop-
shire ewes were in heat during April. From the Ramb. x Dorset Horned
ewes 12:53 were in heat during February, while 40 and 203 of the Oxford
ewes were in heat during March and April respectively: Second heat after
a normal dioestrus p riod was not found in any of the ewes from the above
groups. This showed that ewes of all breeds represented in th's flock
were undergoing a period of anoestrum during Spring and early Summer mon-

ths. Such a sporadic occurrence of heat as was obs.rved in February, harch

and April could hardly be called a heat of the bree ing season.

The earliest oestrus that was followed by regularly recurring heat
periods was observed on June 27 in the Ramb. x Dorset Horned group and by
the end of July, 3.33% of the ewes were in heat.

This group was followed by the Dorset Horned ewes in which July 6,
marked the first heat of the breeding season and by August 10, the whole
group was in heat at-least once.

The Hampshire ewes came next in which the first oestrus of the breed—
ing season was observed on July 24 and by the end of August, 83.33% of
them were in heat. The last heat covering the entire group was seen on
September 2.

In the Shropshire group the first oestrus that was followed by others
in regular succession, was seen on August 16, and by the end of this month,
36.36% of the ewes had been in heat. By September 2, 54.59% of the ewes
were in heat at-least once.

In the Southdown and Suffolk groups, the first heat recorded was on
August 23 and 19 respectively. In the Southdown ewes, the second oestrus
was seen on August 30 but no Suffolk ewe was found in heat till August 31.

Regarding the Oxford group, only one oestrus was seen on August 9 and
no more until August 31.

The breeding season therefore, started in the last week of June and
the first week of July in the Dorset Horned and Ramb. Dorset Horned groups,
in the last week of July in the Hampshire, third week of August in the
Shropshire and in the last week of August in the Southdown and Suffolk
groups. As the second oestrus was not recorded in the Oxford group with-

in an interval of 3 weeks that marked the close of obServations, therefore

-77-

it was concluded, that the breeding season did not set in until August 31
in this group.

In view of the fact, that All the ewes that comprised this flock,
were practically of similar ages and were subjected to the same environ-
mental conditions through-out the experiment, the logical conclusion that
followed was, that ewes of different breeds had different sexual behaviour
under similar conditions and that these differences were heréditary in
nature.

Henning and McKenzie (1927) reported, that out of the two groups
of Grade Merino and Dorset x Merino HLewes, the rate of conception in the
first year was 38%, 48% and 4% during June, July and August. Next year
the conception rate was 84% in June, 8% in July and 2% in September and
October each.

Comparing the above results with the present, 28.5 S of the ewes of
Ramb. x Dorset Horned group were in heat in June against 38 and 84% found
by the above workers. In July, 83.33 and 66.663 of the ewes of Ramb. x
Dorset Horned and Dorset Horned groups were in heat as compared with 48
and 8% in the same months reported by those workers. In August the per-
centage of conception was 4 as compared to 66.66 and 100.00% in this ex-
periment. Such a variation was but natural as the ewes were not bred in
this case, while all in heat were bred by those workers, and the ewes that
came in heat next month were either in first heat or those that did not
settle or both. With this in view, the results were similar in both cases
except that the breeding season started in June which was a few days earl-
ier than in this case. This departure was not an unexpected one, keeping

in view the breed and environmental differences in the two cases.

McKenzie and Phillips (1930) observed, that in 1929 and 1930, the
breeding season started in the last r390k of August, but the Harpshi1re ewes
started breeding 10 days earlier than the other two groups of Shropshire
and Southdown ewes.

The breeding season in the Hampshire ewes observed in this case,
started between the last week of July and first week of August and in the
third and fourth week of August in the Shropshire and Southdown ewes re-
spectively. The results were thus very similar with the above workers in
the similar breeds.

McKenzie and Terri1(1937) found, that the breedir g season star ted in
the middle and ls eek of August in Hampshire ewes in 1930, 1934 and
1935. In the Shropshire and Southdown owes observed in 1929 and 1930, the
breeding season began in the first and second week of September. In this
case too, the results were practically similar except that the Shropshire
and Southd own ewes started coming in heat a few da ys later than in the
present case.

Schott, Phillip us and Srencer (1939) found in connection with a hot-
house lamb project, that each month from May through October, the percent-
age of the Dorset ewes that settled was 35. 44, 5.00, 2.74, .52, 44.11
and 57.14 reSpectively. In the Dorset Horned group observed at the Richi-
gan Station, 66.663 of the ewes were in heat during April and July and
100.00% in August whi 1e no oestrus was recorded in M y and J iae. With such
a large number of ewes observed by Schott et a1. (79, 60, 73, 57, 34 and
7 each month), it at ould not be surprising to find such variations when
only 3 ewes were observed in this ea se.

Kelly and Shaw (1943) reported, that among the Dorset Horned ewes in

.79-

Australia, the percentage of oestrus was from 94 to 100 from February to
July, 35 and 41 in January and August respectively, and zero from Sept-
ember through December inLl938. In 1939, 100 to 67% of the ewes were in
heat from February through July and 33 and 11% in January and August. From
September through December, the frequency of oestrus was again zero (
Spring in Australia and Fall in U. s. are similar). Similarly in the four
different strains of Australian Marines observed from 1936 to 1941, these
workers found that the frequency of oestrus in the Spring and early Summer
months (September to December) was almost zero, a gradual increase was ob-
served in the late Summer and the p ak figures were reached in the Autumn
months. It may be noted that the sexual behaviour of ewes reported by
these workers was on the whole, similar in flocks located at stations 13°
of latitude apart. The results of the present work were again comparable
with the above so far as the seasonal breeding habits of the ewes were con-
cerned in the same as well as different breeds.

Hammond (1944) observed, that in the Suffolk x Border Leicesteerhe—
viot ewes, the earliest and latest dates of the onset of breeding season,
were September 18 and November 5 respectively from 1932 to 1939 in Great
Britain. In view of the breed, strain and environmental differences, the
onset of the breeding season was not very different.

So far as the sexual behaviour of the breeds of British or more truly
of European origin is concerned, the common conclusion dr wn by workers
at the different times is, that ewes irrespective of the breed, individual
and environmental variations, observe the phenomanon of seasonality in
breeding only once a year. The breeding season starts in late Sumner, the

peak figures are reached in Fall and the end of Winter marks the closing

-eO-

phase of the breeding season, and that they observe the same cycle even
when transfered from Northern to Southern HemiSphere (Yeats 1949). The
findings of the present work also support the above results.

The breeding habits of the Indian breeds of sheep were found some—
what different when the literature was reviewed in this connection.

Villages (1929) reported, that a group of Indian bleed ewes in which
33 matings were recorded in Phillipine, observed two breeding seasons,
one in Mhy and June when 39.3% of the ewes mated, and the other in Do-
cember when 21.2S of the matings were observed. In the rest of the months,
the matings ranged from zero to 9.1% of the total.

Smith and Hussein (1935) showed, that during 1927 - 28, 1923 - 29
and 19T9 - 30, out of a total of 507, 490 and 548 ewes of Kisser Dale and
Bikaner breeds, 77, 86.5 and 81.43 lambed from Fall matings (September to
ievember). On the other hand in 1930 — 31, 1931 - 32 and 1932 - 33, out
of a total of 441, 574 and 689 ewes, 86.1, 81.9 and 77% lambed fnlm Spring
matings (March to June). These figures showed that the breeding chances
in the Fall and Spring were practically similar.

It may be pointed out that the Hissar Dale breed was developed at the
Government Cattle Farm, Hissar maintained by the Punjab Government in the
United India. The two breeds used for crossing were Bikaner and Herino.
The ewes that were in mating during Falls and Springs consisted of both
Hissar Dale and Bikaner breeds with the former predominating. In view of
the fact, that the Merino ewes experience only one breeding season a year
(late Summer and Fall) and their progeny experienced two, it follows that
the character of breeding twice a year was transmitted by the Bikaner

parent.

-81-

This view was further substantiated by the findings of Smith and
Singh (1937) at the same Farm. They found that Eikaner ewes came in heat
regularly from march to June by subjecting two groups of these ewes to

aily observations during the above period. This shows that Indian breeds
of sheep (Bikaner and Hissar Dale) have different breeding habits than
European ewes and they likewise observe them when taken into other count-
ries (Phillipine). How far the different breeds in Pakistan resemble the
either variety is a matter to be explored and proven on basis of the ex-

perimental evidence.

hodificatien of the Natural Breeding Season
Length of Light Allowed

Sykes and Cole (1944) reported, that out of 8 ewes (l Southdown, 1
hampshire, 2 Rambeuillet and 4 Crossbred), 5 were bred in the Spring of
1943 from April 16 to June 6 when they were subje ted to the effect of the
decreasing day light length. by the end of March, 3 hours of day light
were added to the normal d.y so that the ewes were getting about 15% hours
light, almost e ual to mid June day. The light was then decreased by one
hour each week, so that by the middle of May, the ewes had only 9; hours
light, almost equal to the day length in the end of November (Fig. 11).
Four out of the 8 ewes came in heat between April 16 and 21. At this
stage, the ewes were having 12% hours daily light equal to about mid Sep-
tember day when normally the breeding season starts almost in every breed.

Yeats (1947 and 1949) showed, that the seasonal changes in the length
of day determined the tine of the year at which the Grade Suffolk ewes ex-
perience their breeding season under natural conditions in Cambridge, and
that it may be modified or even reversed by the alteration of daily light
allowed. The ewes were subjected to such controlled conditions of lighting,
that in actual Sumner they had the Vinter day length and vice versa. By
such modification of the daily light allowance, he found that the ewes start-
ed coming in heat after 10 - 14 weeks of the change from increasing to the
decreasing light. On the other hand, breeding activities ended after 10 -
14 weeks, when the change was made from the decreasing to increasing light

of the day. The change in light allowance in this case was very gradual,

to about 4 minutes a day.

(D
e
’24
f.

1r.-

iniler work was done by Terry(l951) at the Michigan State College ,

a

A .

L

-83-

who found that in a period of 69 ays of observation (June 22 to August
29), out of the 3 groups of 8 ewes each (control, constant light and con-
stant darkness), one ewe lcmbed earlier in the constant darkness group, 4
from the consta at light group, while in the control group no ewe lamhed
earlier. These results were appa‘antly contrary to the hypothesis offer-
ed by Yeats, that the breeding activities came to stand-still under the in-
creased effect of light.
Applying the decreasing day light hypothesi sto the results obtained

in this Cerriment, the breeding season started in about the second week

of the decreasing ight of the day in the Dorset Horned and Ramb. x Dor-

set Horned groups, 4 weeks after in t‘e ham shire, 7 weeks in the Shrop-

shire : Md w;eks in the Southdown and Suff olkw Owoups under natural con-

Temperature
A common belief xists among the breeders, that theonset of cool

nights in Fall is somehow related to the breeding season in sheep. Figure
12 and 13 show the average monthly minimum and ma}:imum tem :er ratures from
March through August and such daily ten eratures for July and August that
prevailed at Ea st Lansi.g in 1951. It may be noted *h hat the breeding sea-
son started in July in 3 breed groups under observation (Dorset Horned,
Ramb. x Dorset Horned and Hampshire) when the average minimum temperature
was highest (59.33. On the other hand, in March, April and May, when the
averaée minimum temperature was 26.20, 35.50 and 47.49F, no breeding act-
ivi ity of the nature ofa breeding season was noticed. This showed that
the onset of cool nights alone was not the determining factor. his view

was further supported by the findings of McKen ie (1939) who observed no

-34-

change in the onset of breeding season among ewes that were subjected for
12 - 24 hours each day to a temperature of 44 - 48°F. in eobled rooms when
the atmOSpheric temperature ranged from 70 to 95°F. The work ias repeated
next year with the same results.

To sum ug.the hypothesis that the decreasing length of the day, acted

as a stimulus in bringing the ewes to heat has sounder experimental evi-

dence behind than the assumption of cool nights. On the other hand, cool

C+

to the decreasing and antagonistic to

l
C.)

night might have an additive effee
the increasing length of the day. n experiment designed, to evaluate the
relation between the two factors (decreasing light and cool nights) rill

certainly add a useful information to th present conception.

 

 

 

 

 

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“LL:

5.

7.

SUI-1 41+—.Y
The sexual behaviour of 47 yearling ewes of the Dorset Horned, Ramb.
x Dorset Horned, Hampshire, Oxford, Shropshire, Southdown and Suffolk
breeds was studied from January 15, to August 31, 1951.
The flock was checked once a day up to August 12 and twice a day there-
after.
Oestrus lengths of -24, /24 and /18 hours were observed in ewes of
different breeds, but no oestrus of less than 12 or equal to 72 hours

was noticed. hajority of the periods of -24 hours duration were ob-
served in the Shropshire ewes but in the Hampshire group, the durations
of /L8 hours were more frequent. In the entire flock however, the
commonest duration was /24 hours.

Dioestrus periods ranged from 118 to 12 but durations of 12 to l5 days
were considered normal with r mean of 13.71 and standard deviation of
f 0.7 days.

Oestrus cycles varied from 122 to 15 days in length but range of 18 to
15 was considered normal with a mean of 16.71 and standard deviation of
f 0.7 days.

The data indicated that some ewes of the Dorset Horned, Hampshire, x—
ford, Shropshire, and Ramb. x Dorset Horned groups came in heat during
Spring, but second oestrus was not found in any of these ewes. On the
other hand, the earliest heat that was followed by regularly recurring
ones, was observed on June 27. The ewes of all breeds therefore, went
through a period of sexual quiesenee in Spring and early Sumner except
for sporadic occurrence of oestrus.

The breeding season began in the last week of June and first weel of

r‘

1'30

rf.
q‘, -

July in the Dorset Horned and Ramb. x Dorset horned froups, end of July

amnshire, third week of August in Shrops ire and in the last week

Ho
:3

of August in the Suffolk and Southdown groups.
The breeding season started in July in two breed groups when the aver-

aee minimum temperature was higher tha any month from March to August.

0

«F‘
.L

Onset of oestrus in 22 ewe lambs as calculated rom the 1am ing dates,
occurred at an average age of 257 in the Hampshire, 255 in Oxford and
257 davs in the Shropshire breeds. The mean age of all groups was found
to be 256 days. I

Analysis of the breeling records of the College breeding flock from
1948 through 1951 revealed, that the majority of ewes irrespective of
the individual and breed variations settled in October. It may be noted

that late dates of conception in certain cases were due to infertile

rams in the early breeding season.

-90-

SELEC ‘TED BILLIOGRAPHY

Cole, H. H., and R. F. Miller. The Changes in the Reproductive Organs
of the Ilwe with Some Data Be r ng on Their Control. nerican qur. of
Anatomy. 57(1935), pp. 39-97.

Gunn, R. M. C. Breeding Cycle of She a in Australia. Pa storg; Review
and Grazier's Record. 58 (December 1943), pp. 1159-1100.

 

 

Hammond, J. On the Erooeding Season? in Sheep. Jour. Agr ._Sc i. (England).
V01. 34, No. 2 (Aprill 1944), pp 7.

Kenning, N. L., and P. C. McKenzie. %t }iouse Lamb Production. Penns.y
lvania Agr. Ex-. Sta. Enml.209, 1927.

Horlacher, L. J., and C. Eammonds. Sheep. Danville: The Interstate
Publisher, 19 45, 3/3 no

*J‘

Kanmlade, N. G. Sheep“ m cienee. New York: J. B. Lippincott Company,
1947, 53 ;/' :J0

Kelly, R. E. Studies in Fertility of Sheep. Cvuncil for Sci. and In-
dust. Research Australia, Lull. 112, 1937.

3611?, R- 8., and H. E. E. Shaw. Observations on the Periodicitv of

Oestrus in Certain Australian Merino Ewes nd II elf-bred Group. £9 .
Coune. for Sci. and Inlus ria Research Australia. 12 (Feb. 1939):

 

:‘p o 13:1-22 o

0%
go

Kelly, R. L., and H. E. B. Shaw. Fertili nSheop (An Exp. Study of
Periodicity of Oestrus a n9 asons in Australia). Council
for Sci. and Indust. Research Australia, :ull. 106, 1943.

McKenzie F. F. and R. M. Phillips. Some Observations on the Ge est trual
9 2 .
Cycle in Sheep. The Aneric n Society of Animal Production Prose egings.
1930, pp. 138-143.

McKenzie, F. F., and C. E. Trrril. Oestrus, Ovulation and Related Phe-
nomenon in the Ewe. Missouri Agr. Exp. Sta. Res. Bull. 264, 1937.

McKenzie, F. F. Applioa ation of Reprodlctive UPhysiolo'y to Live-stock
Breeding. Growth. Vol. 3,10. 3(1939), 276—293.

Roux, L. L. Sex Physiolo y of Sheep. Onde rsteooort Jour. Vet. Sci. and
Ani. Ind. 6, 2 (April 1936), pp. 465-717.

Schott, R. G., R. M. Phillips and D. A. Spencer. The Occurrence of Oestrus
in Sheep and its Relation to Extra-s -asonal Product ion of Lambs. Th
American Society of Anizial Production Proceed ix :gs. 1939, pp. 347-3 53.

-91-

Sinclair, A. N. A Note on the Presence of Rams on the Incidence of
Oestrus in Maiden fierino Ewes during Spring Mating. Australian Vet-
erinary Journal. 26 (Feb. 1950), pp. 37-39

Smith, L. U. and M. Hussain. A Study of the Effect of Climatic Seasons
on certain Phases of Sheep Husbandry at the Government“ oat tle Iarm His-
sar. A.“ricu1true and L V1? —stock in Irdia. 5 (1935), pp R6-138.

 

Smith, L. 11., and G. Singh. A Preliminary Note on fin

e Study of Oestrus
in Sheep. Agriculture a_-d Liv o ck .n Iniia. 8 (193

8), pp. 683-686.

Sykes, J. F., and C. L. Cole. Modification of Rating Season in Sheep by
Light Treatment. Michigan Agri. Exp. Sta., Quarte’ly Bull. 26: 4, 1944.

Terril, C. E. Oestrus and Ovulation in the Ewe. The American Society of
An1rwl Prediction Proceedinr s. 1935, pp. 153-158. .

Terry, M. A. The Effect of Constant Li .ght or Darkness on the Thyroid
Gland of the Sheep and on the Oestrus C cle. ”Unpubi shed M. S. thesis”
Hichigan State College, 1951, 51 pp.

Valente, V. The Trend of Sexual an Reproductive Seasons am ng Horses,
Cattle, Water Buffaloes, Sheep and Coats under Los Banos Conditions.
Phillipdne Asriculturist. 17 (1929), ?p. 477-485.

Valente, V. The Breeding Habits 01 Sh neep and Goats. Asricxltm ral and
Industrial Life. 12 (March 1953), nip. 22.

g

\

Winter, L. M. Animal Breeding. New Yora: John Wiley and Sons Inc., 1944,
316 pp.

Yeats, N. T. M. Influence of Variation in Length of Day upon the Breeding
Season in Sheep. Natuie (London) 160 (Sept. 10 47) pp. 429-430.

 

Yeats, N. T. M. The Breeding Season of the Sheel': with Particular Reference
to its Ioiification by Artificial Keans using Lights. Jour. of Agri. Sci.
(England). 39 (1949), pp. 1 —43.