March, 1953]. D. P. MUKHERJEE, A. ROY AND P. BHATTACHARYA 5
that the sperm concentration of the control group gradually decreased during the
experimental period. Administration of thyroprotein to the animals of the exper-
mental group not only prevented this decrease but also raised the sperm concen-
tration. ' Reaction time ' and the rest of the semen characteristics did not appear
to have been greatly affected by thyroprotein feeding. Table I shows the average
' reaction time, ' and, the averages of the semen characteristics of the two groups,
together with the results of statistical analysis of data regarding these characteris-
tics during the entire experimental period. The statistical analysis was done
according to the method described by Goulden [1939].
During the pretreatment period, the two, groups were almost identical in all
the characteristics under study, except in the percentage of abnormal spermatozoa.
The difference in the average percentage of abnormal spermatozoa between the two
groups was found to be highly significant, the average in the experimental group
being higher than in the control group. During the treatment period, highly signi-
ficant differences in volume of semen, sperm concentration and percentage of abnor-
mal spermatozoa were found in the two groups. The differences in average ' reaction
time ' and other characteristics of semen as found between the two groups were
due to chance variation. The experimental group showed a highly significant
decrease in semen volume as against the control group, but it showed a
highly significant increase in the sperm concentration. As in the pretreatment
period, the difference in the percentage of abnormal spermatozoa remained highly
significant ; the percentage in the experimental group was higher than in the control
group.
It seems, therefore, that the dosage of thyroprotein administered to the animals
had an adverse effect on semen volume. It undoubtedly increased the sperm
concerntration per ml. of semen, but failed to reduce the percentage of abnormal
spermatozoa.
DISCUSSION
As the various methods used for evaluating the quality of semen are all sub-
jective and as no one method gives a correct appraisal, it is desirable that each
semen sample be subjected to several methods of analyses. Various physical tests,
therefore, were made in this experiment while studying the effect of thyroprotein
feeding on semen quality of goats during an unfavourable part of the year. The
results show that feeding of 1 gm. of thyroprotein daily increased the sperm con-
centration per unit volume of semen. This result, on the whole, agrees with that of
Bogart and Mayer [1946] in rams. It appears that of the many probable factors
one, which perhaps accounts for low sperm concentration in goats during the un-
favourable seasons [Shukla and Bhattacharya, 1947 b], is subnormal secretion of
thyroid hormone.
It is common experience of workers in artificial insemination of farm animals
that high initial motility is generally found to be associated with high sperm con-
centration. The reason for the absence of significant difference in average initial
motility between the experimental and control groups might be due to the fact
that initial motility rating as appraised in this experiment was not determined by
a very precise method for evaluating semen quality. The method could at best