118 SEASONAL VARIATION IN REACTION TIME [Vol. XXII, Part II,
except ram 46 with, which it did not differ significantly. Similarly ram 49, which,
had significantly lower pH than rams 3, 67, 74 and 30, had significantly higher average
sperm concentration than all these rams. It is apparent, therefore, that low pH
of semen in rams was associated with higher sperm concentration and vice versa.
As has been stated before, total number of spermatozoa per ejaculate was obtained
by multiplying total volume of semen and the sperm concentration per unit volume.
It was expected, therefore, that in rams with higher total volume and sperm con-
centration the total number of spermatozoa will be higher. This was found to be
true in the case of ram 47, which had a higher volume of semen than all other rams
excepting ram 27 and also had the highest sperm concentration and total number
of spermatozoa. Rams 27, 47 and 74 did not significantly vary in their total
volume of semen. But as there was significant variation in their sperm concentra-
tion their total number of spermatozoa also significantly varied. Rams 46, 49
and 65 did not significantly vary in their total number of spermatozoa. This was
because there was neither significant variation in their total volume of semen nor
in their sperm concentration. Rams 30, 3 and 67 did not vary in their total number
of spermatozoa although there was significant variation in semen volume between
ram 30 and the other two. This might be due to small range of variation between
these rams in their sperm concentration. As regards the percentage of abnormal
spermatozoa the table shows that ram 3 differed significantly from the rest of the
animals.
Critical difference of variable factors between years is presented in Table V.
From the table it is apparent that during the second year the rams took significantly
lesser time to mount an anoestrous ewe as shown by the 'reaction-time'. The
quality of semen during the second year deteriorated as is evident from higher pH,
lower sperm concentration and the total number of spermatzoa than in the first
year. The decrease in the average 'reaction-time' in the second year might be due
to the fact that the trained rams after a few months of semen collection at a particular
place became so familiar with the place that as soon as they were brought to the
place and near an ewe they anticipated service and therefore took lesser time to
ejaculate semen in artificial vagina than in the initial stage of the experiment.
No satisfactory explanation for the deterioration in semen quality during the second
year of the experiment seems possible unless the various contributory factors for.
semen production are studied in detail, Mukherjee and Bhattacharya [1947] also
observed deterioration in semen quality of bulls as shown by higher pH and lower
initial motility in the second year of their experiment.
Critical difference of the variable semen characteristics between seasons has
been presented in Table VI. From the table it is evident that the average volume
of semen in autumn and winter was significantly lower than in spring. Initial
motility in winter and autumn was lower than in spring and summer. Average pH
of semen during winter and spring was significantly lower than in autumn and
summer. In autumn sperm concentration and total number of spermatozoa were
lower than in other seasons. In autumn and winter the percentage of abnormal
spermatozoa was higher than in spring and summer. This was due to the appearance
of increased numbers of tailless spermatozoa in autumn and 'bent tail' spermatozoa
in winter in the ejaculates. From the table it is evident that the semen quality