Published online by Cambridge University Press: 18 August 2016
To determine how weaning date affected productivity in deer farming systems, calf growth rate, hind conception date, and hind condition were monitored on 10 New Zealand deer farms located in Otago and Southland, from February/March until August/September in 1999 (no. = 551 hind-calf pairs) and 2000 (no. = 414 pairs). On each farm, in both years, half of the hind-calf pairs were separated for early weaning (mean date 11 March; range 25 February to 17 March), while the other half remained together for late weaning (mean date 28 May; range 12 May to 10 June). Deer in both treatments on each farm were of similar age and genotype and stags were added to hind groups on the same day in March. Calves were weighed in February/March, May/June and August/September. Scanning of hinds to determine date of conception was carried out in June.
Climatically the 2 years were very different with a summer drought preceding observations in 1999, nevertheless similar effects of weaning date were observed in both years. Calves weaned early gained less weight than the late-weaned calves (142 v. 210 g/day in 1999, and 131 v. 166 g/day in 2000) between February/March and May/June (P < 0·001). However mean conception dates were earlier in the early-weaned hinds compared with the late-weaned hinds (by 12 days in 1999 and 7 days in 2000,P < 0·001). Hind condition scores in May/June were higher for the early-weaned hinds compared with the late-weaned hinds (by 0·5 score units in 1999 and 0·3 score units in 2000, P < 0·001). For all measures the effects of weaning date varied between farms (P < 0·001). It was concluded that farmers weaning early could expect a positive effect on hind conception date and winter hind condition and a negative effect on calf growth rate, but management could override negative effects of weaning early or late.