December, 1955 ] N. S. KUSHWAHA, D. P. MUKHERJEE AND P. BHATTACHARYA 323
Volume depends mostly on the secretions of the accessary reproductive organs,
viz., seminal vesicles, prostate and Cowper's glands, etc. In big farm animals like
buffalo-bulls and bulls where the volume of semen is more than in the small animals
like sheep and goats, the secretions of the accessary reproductive organs are more.
It seems, therefore, that the variation, if any, in secretion of different accessory
reproductive organs due to climate in relation to the total volume obtained may not
be so great as in the case of small animals. As a result, the data on volume in
bulls and buffalo bulls failed to show any significant difference between seasons.
pH of semen
The hydrogen-ion concentration of semen failed to show significant variation
between seasons. This result is in agreement with those obtained in bulls by Mukher-
jee and Bhattacharya [1952] and in goats by Shukla and Bhattacharya [1952, b]
but is contrary to what has been obtained in sheep by Shukla and Bhattacharya
[1952, a]. Bogart and Mayer [1946] have pointed out that among the farm animals,
the most marked seasonal change in the physiology of reproductive organs occurs in
rams. The results obtained in the present experiment and those obtained in bulls,
sheep and goats confirm the observations of Bogart and Mayer. As the most marked
seasonal change takes place in sheep and as pH is an indirect estimation of sperm
concentration, it may be the reason why seasonal change in pH of ram semen has been
observed and not in any other farm animals.
Initial motility
This was determined by microscopical examination of a drop of fresh semen.
Its rating, therefore, depends on (i) activity and (ii) concentration of spermatozoa
in the sample. It was expected, therefore, that higher the sperm concentration
greater would be the initial motility. It may be seen from Table IV that this is
so, and the results obtained on the whole agree with the results obtained in bulls,
sheep and goats. In summer and spring, there was no significant variation in
sperm concentration but there was significant variation in initial motility which was
significantly lower in summer than in spring. This may be due to the percentage
of abnormal spermatozoa being significantly higher in summer than in spring.
Sperm concentration
Of the semen characteristics studied in the present experiment, the number of
spermatozoa per unit volume of semen is the most important and reliable characteri-
stic in evaluating the quality of semen. The results obtained show that in winter
sperm concentration was significantly lower than in spring and summer. In autumn,
the concentration was significantly lower than in summer. This result is contrary
to what has been obtained in bulls by Mukherjee and Bhattacharya [1952] and in
sheep and goats by Shukla and Bhattacharya [1952, a and b]. In these three species
of farm animals, lowest sperm concentration was obtained in autumn and highest
in spring. Winter was the second best season, and in summer the concentration
was higher than in autumn. In the present experiment, lowest sperm concentration
was obtained in winter and there was neither significant variation between autumn