Influence of castration and level of intake of a commercial concentrate (0, 2% BW, or ad libitum) on growth performance and carcass characteristics of finishing Boer-cross meat goats1

This trial evaluated growth of 22 bucks and 22 wethers (at least 3/4 Boer) through weaning (at 75 d of age), after which 18 bucks and 18 wethers were fed for 84 d to examine the effect of castration and nutritional plane (hay only; 2% BW as concentrate pellets with ad libitum hay; or ad libitum concentrate pellets with 0.75% BW as hay) on growth and carcass characteristics (with age at slaughter 188 d). Bucks tended to gain more rapidly than wethers before weaning (ADG = 167 vs. 147 g/d for bucks and wethers, respectively; P = 0.082). During finishing carcass-adjusted ADG was greater (P < 0.001) for bucks (143 g/d) than for wethers (110 g/d), as was DMI (800 g/d for bucks and 685 g/d for wethers). Kids fed hay only gained 2 g/d on a carcass-adjusted basis, whereas the kids receiving 2% BW as concentrate gained 123 g/d, and the ad libitum concentrate kids gained 256 g/d (P < 0.001). Bucks had better live grades than did wethers (2.27 and 2.56 for bucks or wethers, respectively; P = 0.006). Kids consuming hay only had lower live and carcass grades than did the kids consuming 2% BW concentrate, which in turn were lower than kids receiving ad libitum concentrate (P < 0.001). Castration did not affect ruminal parameters, serum urea N, or liver Cu levels. The hay-only diet resulted in more neutral ruminal pH, reduced total ruminal VFA, and less liver Cu than the diets supplemented with concentrate (P < 0.003). Castration impeded pre- and post-weaning growth without improving carcass quality. Supplementing an all hay diet with 2% BW as concentrate improved growth and carcass quality. Increasing supplementation to ad libitum further improved growth rate and carcass quality. Further research is needed into the safety and economic efficiency of self-feeding programs for meat goats.