GROWTH AND REPRODUCTIVE DEVELOPMENT OF RED DEER CALVES (CERVUS-ELAPHUS) BORN OUT-OF-SEASON

Since the productivity of farmed red deer is constrained by their inherent seasonal biology, the potential advantages of breeding out-of-season following melatonin administration were investigated. Calves born in February (F; no. = 8) were heavier at weaning in September of the same year than calves born with normal birth dates in June (J; no. = 8) (73.2 v. 441 (s.e.d. 3.59) kg; P < 0.001) and at the end of April of the next year (88.0 v. 67.6 (s.e.d. 6.44) kg; P < 0.01) although their suckled live-weight gain to 100 days of age was lower (304 v. 361 (s.e.d. 21.4) g/day; P < 0.05). After weaning, F calves had higher voluntary food intake than J calves (g dry matter per head per day) from September to November (1643 v. 1124 (s.e.d. 92.6); P < 0.001), November to February (1435 v. 916 (s.e.d. 67.9); P < 0.001), and February to April (1487 v. 1059 (s.e.d. 115.5); P < 0.01). Unlike J calves, F calves showed puberty in their first autumn. F male calves (no. = 3) grew antlers which hardened in November, whereas J males (no. = 3) did not, and F males, aged 8 months, had significantly higher mean plasma concentrations of testosterone than J males, aged 4 months (1-35 v. 0.28 (s.e.d. 0.154) mug/l, P < 0.001). Oestrous cyclicity was observed in 3/5 group F females, aged 9 months, but in 0/5 group J females, aged 5 months. Although the dams of F and J calves had similar live weights at mating, birth and 100 days post partum, F dams were heavier (P < 0.05) at weaning. Following parturition, F dams had a mean voluntary food intake of 2700 (s.e. 110) g dry matter per head per day from February to April.