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 weeks 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, n = 5), were kept in constant intermediate 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 concentrations were higher in group L than in group S from birth to 20 weeks of age (averaging 1.55 versus 0.48 ng ml-1, P < 0.001), from 21 to 45 weeks (1.65 versus 1.32 ng ml-1, P < 0.05) and from 46 to 50 weeks (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 concentration of plasma testosterone was relatively low from birth to 30 weeks (averaging 0.38 and 0.27 ng ml-1 (P < 0.05) in groups L and S, respectively), but thereafter increased to a maximum which was greater (2.78 versus 1.46 ng ml-1, P < 0.01), and occurred earlier (47 versus 68 weeks of age, P < 0.001) and at lower body weight (82 versus 96 kg, P < 0.01) in group L compared with group S. Growth of antlers started in both groups at 25 weeks, but they hardened earlier in group L than in group S (42 versus 47 weeks of age, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)