INFLUENCE OF PRENATAL PHOTOPERIOD ON POSTNATAL REPRODUCTIVE DEVELOPMENT IN MALE RED DEER (CERVUS-ELAPHUS)

Male red deer calves, whose mothers had been kept for the last 14 week s of gestation in long days (18 h light:6 h dark) (group L, n = 7) or short days (6 h light:18 h dark) (group S, 5), were kept in constant i ntermediate daylength (12 h light:12 h dark) from birth to 75 weeks of age. Both groups showed the same live-weight gain. Mean plasma LH con centrations were higher in group L than in group S from birth to 20 we eks of age (averaging 1.55 versus 0.48 ng ml(-1) P < 0.001), from 21 t o 45 weeks (1.65 versus 1.32 ng ml(-1), P < 0.05) and from 46 to 50 we eks (1.84 versus 1.27 ng ml(-1), P < 0.001); thereafter, there was no significant difference between the groups (1.81 ng ml(-1)). Mean conce ntration of plasma testosterone was relatively low from birth to 30 we eks (averaging 0.38 and 0.27 ng ml(-1) (P < 0.05) in groups L and S, r espectively), but thereafter increased to a maximum which was greater (2.78 versus 1.46 ng ml(-1), P < 0.01), and occurred earlier (47 versu s 68 weeks of age, P < 0.001) and at lower body weight (82 versus 96 k g, P < 0.01) in group L compared with group S. Growth of antlers start ed in both groups at 25 weeks, but they hardened earlier in group L th an in group S (42 versus 47 weeks of age, P < 0.05). These results pro vide evidence that in male red deer postnatal photoperiodic change is not required to trigger puberty, that prenatal photoperiodic history i nfluences postnatal reproductive development and that the timing of re productive maturation in deer raised on 12 h light:12 h dark is advanc ed by long days experienced prenatally.