Effects of restricting body weight gain or limiting the photoperiod during rearing on sexual maturity,viability and semen production in large white Turkey males

1. Severe restriction of food from 6 to 54 weeks of age resulted in lower body weights and smaller testes weights in male turkeys.

2. As a proportion, mortality was 0.5 in turkeys fed ad libitum and 0.1 in those which were restricted. There were significantly fewer leg problems in the birds undergoing food restriction.

3. Sexual maturity was delayed 4 weeks by food restriction although semen quality was similar to that in ad libitum‐fed birds.

4. Individual semen production was lower after food restriction but, because mortality and food consumption were also lower, semen production per male housed and semen production per kg of food eaten were proportionally 0.30 and 0.32 greater in restricted‐compared with ad libitum‐fed turkeys.

5. Useable quantities of good quality semen were obtained from ad libitum‐fed turkeys at 23 weeks of age.

6. A short photoperiod (7L:17D) from 10 to 18 weeks of age in ad libitum‐fed turkeys produced more rapid development of normal semen production compared with turkeys given a longer photoperiod (14L:10D).