The effect of photoperiod and feed restriction on semen production in the turkey

In Experiment 1, 72 yearling Broad Breasted White Turkey males were induced to molt under either stimulatory (16L:8D) or nonstimulatory (8L:16D) light used concurrently with a short period of feed and water deprivation, and followed by periods of daily feed restriction (50% of full feed). One-fourth of the males wer killed at intervals of 4, 8, 12, and 16 weeks and their testes weighed. In Experiment 2, 40 yearling Broad Breasted White males were killed at 2-week intervals during an 8-week period of 8 hr light per day followed by a 10-week period of 16 hr light per day. Testes were removed, weighed, and fixed in Bouin's solution for histological preparation. In Experiment 1, birds kept under 16 hr light and given different periods of feed and water deprivation, followed by 8 weeks of feed restriction, failed to terminate semen production, although their testes were reduced substantially in size and function. Other groups of males given 8 hr light per day with concurrent regimens of feed deprivation and daily feed restriction, terminated semen production within 4 weeks. When returned to 16 hr light, the testes were twice as heavy as those of males kept in production during the entire test. In Experiment 2, the testes of birds induced to molt under 8 hr light per day regressed by 73% and 89%, respectively, after 4 and 8 weeks of exposure. When given 16 hr light per day, some spermatogenic activity was noted at 4 weeks, and complete spermatogenesis, with maximum semen production, occurred after 6 weeks. There was evidence that a successful rejuvenation of the testes requires a period of complete quiescence.