Nutrition of Rams and Output of Spermatozoa

To determine the time taken for the output of spermatozoa by rams to respond to changes in the diet semen was collected twice daily for 63 days from two groups of rams; one received a high and the other a low plane of nutrition. 'The output of spermatozoa by rams in the two groups began to diverge at the seventh week of differential nutrition, whereas testicular size diverged after four weeks. In contrast, both the live weights and the volume of semen collected began to diverge after one week of semen collection. For all of these parameters the mean values rose for the rams on the high plane of nutrition and fell for those on the low plane of nutrition and differed significantly between the two groups by the end of nine weeks. Because changes in the output of spermatozoa were first evident during the seventh week after changing the diets, it was concluded that the efficiency of stages of spermatogenesis that occur later than the last spermatogonial divisions are responsive to nutrition.