The effect of prepubertal castration of red deer and wapiti-red deer crossbred stags on growth and carcass production

This study investigated the effects of prepubertal castration of red deer and wapiti × red deer (“crossbred”) stags on a yearling (< 12 months old) venison production system. From a pool of 140 red deer and 107 crossbred stags in March, 15 animals were allocated randomly to one of several groups for each genotype. Groups of each genotype were castrated surgically in April, May, June, July, August or September (5-10 months of age) and managed together with intact controls until 12 months of age. Live-weights were recorded every two weeks. A total of 40 red deer and 39 crossbred stags, representing intact controls and stags castrated in April, June and August, underwent CT scanning in November (11 months) for carcass assessment. All animals in the trial were slaughtered in either mid November, early December or late January. Carcass weights and primal joint weights were recorded.Intact stags exhibited a seasonal pattern of growth. However, crossbred stags suffered a notable growth check in June but exhibited greater live-weight gains in late spring to eventually surpass red deer for average live-weight. Castration in April and May was associated with higher daily live-weight gains within 2-4 weeks of castration, perhaps reflecting the effects of chemical treatments for surgery. There were no significant differences in mean growth rates, within genotype, between intact and castrated groups, irrespective of date of castration, until October/November for red deer and November for crossbreds. By late November (11 months) the mean live-weights differed by 4-7 kg for red deer and 2-5 kg for crossbreds (P < 0.05 for both genotypes). The net effects of castration on the mean timing of attainment 93 kg live-weight was 14-23 days delay for red deer and 6-18 days delay for crossbreds for treatments between April and August, inclusive. September castration had a negligible effect for both genotypes. There were no significant effects of castration on carcass musculature, but there were numerous significant breed effects on muscle distribution and fatness. Crossbred stags showed an increase in the proportion of the carcass as hindquarter, but also a reduction in loin and overall fatness. It was concluded that prepubertal castration resulted in relatively small effects on growth prior to puberty and it is possible to meet peak market supply dates with production systems that implement good nutrition and health management.