Department of Animal Sciences, Universidade Estadual Paulista, Jaboticabal, SP 14884-900, Brazil.
Department of Animal Sciences, The Ohio State University, Columbus 43201.
J Dairy Sci. 2017 Jun;100(6):4574-4586. doi: 10.3168/jds.2016-11895. Epub 2017 Mar 23.
Requirements for growth in the different sexes remain poorly quantified in goats. The objective of this study was to develop equations for estimating net protein (NP) and net energy (NE) for growth in Saanen goats of different sexes from 5 to 45 kg of body weight (BW). A data set from 7 comparative slaughter studies (238 individual records) of Saanen goats was used. Allometric equations were developed to determine body protein and energy contents in the empty BW (EBW) as dependent variables and EBW as the allometric predictor. Parameter estimates were obtained using a linearized (log-transformation) expression of the allometric equations using the MIXED procedure in SAS software (SAS Institute Inc., Cary, NC). The model included the random effect of the study and the fixed effects of sex (intact male, castrated male, and female; n = 94, 73, and 71, respectively), EBW, and their interactions. Net requirements for growth were estimated as the first partial derivative of the allometric equations with respect to EBW. Additionally, net requirements for growth were evaluated based on the degree of maturity. Monte Carlo techniques were used to estimate the uncertainty of the calculated net requirement values. Sex affected allometric relationships for protein and energy in Saanen goats. The allometric equation for protein content in the EBW of intact and castrated males was log protein (g) = 2.221 (±0.0224) + 1.015 (±0.0165) × log EBW (kg). For females, the relationship was log protein (g) = 2.277 (±0.0288) + 0.958 (±0.0218) × log EBW (kg). Therefore, NP for males was greater than for females. The allometric equation for the energy content in the EBW of intact males was log energy (kcal) = 2.988 (±0.0323) + 1.240 (±0.0238) × log EBW (kg); of castrated males, log energy (kcal) = 2.873 (±0.0377) + 1.359 (±0.0283) × log EBW (kg); and of females, log energy (kcal) = 2.820 (±0.0377) + 1.442 (±0.0281) × log EBW (kg). The NE of castrated males was greater than that of intact males and lower than that of females. Using degree of maturity for estimating NP and NE, we could remove the differences between sexes. These results indicate that NP and NE differ among sexes in growing Saanen goats, and this difference should be accounted for by feeding systems. Including the degree of maturity as predictor cancels out those differences across sexes in protein and energy requirements.
不同性别山羊生长的需求仍未得到充分量化。本研究的目的是为不同性别的萨能奶山羊制定从 5 至 45 公斤体重（BW）的净蛋白（NP）和净能（NE）生长估算方程。使用了 7 项比较屠宰研究（238 个个体记录）的数据。使用了一种确定空 BW（EBW）中体蛋白和体能量的生物计量方程，将 EBW 作为生物计量预测因子。使用 SAS 软件（SAS Institute Inc.，Cary，NC）中的 MIXED 程序，通过线性化（对数转换）表达生物计量方程，获得参数估计。该模型包括研究的随机效应和性别的固定效应（未去势雄性、去势雄性和雌性；n=94、73 和 71）、EBW 及其相互作用。净生长需求是通过对 EBW 的生物计量方程进行一阶偏导数来估算的。此外，还根据成熟度来评估净生长需求。蒙特卡罗技术用于估计计算出的净需求值的不确定性。性别影响萨能奶山羊的蛋白质和能量的生物计量关系。未去势雄性和去势雄性 EBW 中蛋白质含量的生物计量方程为 log 蛋白质（g）=2.221（±0.0224）+1.015（±0.0165）×log EBW（kg）。对于雌性，关系为 log 蛋白质（g）=2.277（±0.0288）+0.958（±0.0218）×log EBW（kg）。因此，雄性的 NP 大于雌性。未去势雄性 EBW 中能量含量的生物计量方程为 log 能量（kcal）=2.988（±0.0323）+1.240（±0.0238）×log EBW（kg）；去势雄性的 log 能量（kcal）=2.873（±0.0377）+1.359（±0.0283）×log EBW（kg）；雌性的 log 能量（kcal）=2.820（±0.0377）+1.442（±0.0281）×log EBW（kg）。去势雄性的 NE 大于未去势雄性，低于雌性。使用成熟度来估计 NP 和 NE，我们可以消除性别之间的差异。这些结果表明，生长中的萨能奶山羊在性别之间 NP 和 NE 存在差异，饲养系统应考虑到这一点。将成熟度作为预测因子包括在内，可以消除性别之间在蛋白质和能量需求方面的差异。
