38 SEMEN PRODUCTION OF BUFFALOES [Vol. XXIV, Part I,
Each test was conducted after an interval of 24 hours, i.e. after resting the bull
for a day between tests. In the majority of the tests in all the bulls, the total number
of ejaculates taken at rapid succession never exceeded 15. The exceptions are
tests 1 and 2 of buffalo bull No. 23, tests 2 and 3 of buffalo bull No. 28 and tests 1,
2 and 3 of buffalo bull No. 31. The first two tests on buffalo bull No. 23 were carried
out on 15-11-51 and 17-11-51 respectively when the teaser cow was 'on heat'.
The tests on the other two buffalo bulls were conducted from 10-12-51 to 14-12-51,
i.e. after an interval of 25 days. In buffaloes, the length of œstrus cycle varied
from 18-25 days. The teaser cow was again 'on heat' during the collections
taken from buffalo bulls No. 28 and 31. It was not 'on heat' when the collections
from other bulls except buffalo bull No. 24 were taken. In case of bull No. 24
though the cow was 'on heat' when collections were taken from him, it did not
exhibit any increased sex-urge. Since out of the four bulls tested three had shown
unusually high sex-urge, it appeared probable that the abnormally high frequency
of collections obtained per test was due to the physiological state of the teaser
cow. In the three series of experiments reported below only a limited number of
ejaculates (2-4) were taken at a time. This was done because it is customary to
take not more than 2-3 ejaculates at a time and since our chief interest lay in finding
out whether a change in the physiological state of teaser cow produced significant
effect on the efficiency of the customary procedure of collection as judged by the
reaction time and quantity and quality of the ejaculates taken. The other aspect,
namely, the frequency of ejaculates given at a time with changed conditions of
collection could form a subject matter of an independent study.
Details of experiments
The experiments were conducted on the types of Indian buffalo bulls
commonly found in Uttar Pradesh. For the first two experimental series six
buffalo bulls were used, while the third experimental series was run with
12 buffalo bulls. Since the animals were purchased from the local markets,
their exact ages and past breeding histories were not known. They had full
mouths, and appeared young, vigorous and free from all diseases. A short-term
test as described in a separate article was carried out to judge the suitability
of the bulls for artificial service before selecting them for use in the experiment.
They were kept under uniform animal husbandry conditions throughout the
experiments and received rations consisting of wheat bhoosa, greens and
concentrates. The last mentioned was made up of crushed oats and linseed
cakes in the proportion of 2:1 and was fed at the rate of 3 lb. per 800 lb.
body weight.
Experimental series I. Two teaser cows were used. One of the teaser cows
was artificially brought on heat by an initial implantation of 5 gm. stilboestrol
tablet, followed by another implantation of 2.5 gm. of the hormone after a week,
when the animal was showing symptoms of passing heat. Later on the heat was
maintained by periodical injections of 12.5 mg. of stilboestrol in oil suspension
given subcutaneously. In this way the cow could be kept on heat throughout the
experiment. This method had to be adopted to avoid the necessity of having to
use different cows on different days, thereby eliminating the effect of the change in
teaser cows on sex-urge of the bulls. Besides, there was practical difficulty in
obtaining trained teaser cows on heat whenever desired for the experiment. Care