Department of Animal Biosciences,University of Guelph,Guelph,ON,Canada,N1G 2W1.
Animal. 2018 Mar;12(3):648-656. doi: 10.1017/S1751731117002063. Epub 2017 Aug 14.
In order to accurately estimate body composition at slaughter and to meet specific market targets, the influence of age at time of castration (surgical or immunological) on body composition and boar taint indicators must be determined for male pigs. In all, 48 males were randomly assigned to one of four management regimens: (1) entire male pigs (EM), (2) EM surgically castrated at ~40 kg BW and 10 weeks of age (late castrates; LC), (3) conventional, early surgical castrates (within 4 days of birth; EC) and (4) EM immunized with a gonadotropin-releasing hormone (GnRH) analog (primary dose at 30 kg BW and 8 weeks of age; booster dose at 70 kg and 14 weeks of age; IM). Pigs were fed corn and soybean meal-based diets that were not limiting in essential nutrients. Back fat was sampled on days -3, 8, 18 and 42, relative to administering the booster dose of GnRH analog at day 0, to determine androstenone concentrations (n=8 or 9/group). Fat androstenone concentrations in IM were lower than EM between days 8 and 42 after administering the booster dose (173 v. 863 ng/g, respectively; P<0.01), and were not different from surgically castrated males (EC and LC) after day 18. Slaughter occurred at ~115 kg BW, 42 days (6 weeks) after administering the booster dose for IM, and 10 and 20 weeks after surgical castration for LC and EC, respectively (n=8 or 9/group). At slaughter, live BW, liver weight as a percent of live BW, dissectible bone as a percent of cold carcass side, body protein and water contents and whole-body protein deposition decreased with time after surgical castration (linear; P<0.05), whereas dressing percentage, dissectible fat, probe fat depth and body fat content increased with time after surgical castration (linear; P<0.05). The IM had intermediate dressing percentage and dissected fat to EM and EC, whereas liver weight as a percent of live BW and body protein and lipid contents were not different from EM. Whole-body lipid deposition tended to be greater in IM than in EM between 14 and 20 weeks of age (373 v. 286 g/d; P=0.051). In conclusion, castration of male pigs after 6 weeks of age has a lasting effect on physical and chemical body composition. The relationship between time after castration and body composition may be developed to predict carcass composition and can be used to determine the ideal immunization schedule aimed at specific markets in the future.
为了在屠宰时准确估计体成分，并满足特定的市场目标，必须确定雄性猪在去势时（手术或免疫）的年龄对体成分和公猪异味指标的影响。总共 48 头雄性猪被随机分配到以下四种管理方案之一：（1）整个雄性猪（EM），（2）在 40 公斤体重和 10 周龄时进行手术去势的 EM（晚期去势者；LC），（3）常规的早期手术去势者（出生后 4 天内；EC）和（4）用促性腺激素释放激素（GnRH）类似物免疫的 EM（初次剂量为 30 公斤体重和 8 周龄；加强剂量为 70 公斤和 14 周龄；IM）。猪只饲喂玉米和豆粕基础日粮，这些日粮在必需营养素方面没有限制。背脂在 GnRH 类似物加强剂量给药前的第-3、8、18 和 42 天进行采样，以确定粪甾酮浓度（每组 8 或 9 头猪）。在给予加强剂量后 8 至 42 天，IM 组的脂肪粪甾酮浓度低于 EM 组（分别为 173 和 863ng/g；P<0.01），并且在第 18 天后与手术去势雄性（EC 和 LC）无差异。在给予 IM 的加强剂量后约 115 公斤体重和 42 天（6 周）时进行屠宰，在给予 LC 和 EC 的手术去势后 10 周和 20 周时进行屠宰（每组 8 或 9 头猪）。屠宰时，活体体重、肝重占活体体重的百分比、可解剖骨占冷胴体的百分比、体蛋白和水分含量以及全身蛋白沉积随手术去势后的时间而降低（线性；P<0.05），而服装百分比、可解剖脂肪、探针脂肪深度和体脂肪含量随手术去势后的时间而增加（线性；P<0.05）。IM 的服装百分比和可解剖脂肪介于 EM 和 EC 之间，而肝重占活体体重的百分比和体蛋白和脂质含量与 EM 无差异。IM 组在 14 至 20 周龄之间的全身脂质沉积量比 EM 组高（373 比 286g/d；P=0.051）。总之，雄性猪在 6 周龄后去势对物理和化学体成分有持久的影响。去势后时间与体成分之间的关系可以被开发出来预测胴体成分，并可用于确定未来针对特定市场的理想免疫计划。
