Published online by Cambridge University Press: 02 September 2010
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 (}; 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 < 0·02) 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 / calves (g dry matter per head per day) from September to November (1643 v. 2224 (s.e.d. 92·6); P < 0·002), November to February (1435 v. 926 (s.e.d. 67·9); P < 0·002), and February to April (1487 v. 2059 (s.e.d. 115·5); P < 0·02).
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) fj.g/1, P < 0·001). Oestrous cyclicity was observed in 3/5 group F females, aged 9 months, but in 0/5 group ] females, aged 5 months. Although the dams of F and ] calves had similar live weights at mating, birth and 100 days pos t 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.
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