Coutinho C C, Mercadante M E Z, Jorge A M, Paz C C P, El Faro L, Monteiro F M
Faculdade de Medicina Veterinária e Zootecnia, Fazenda Experimental Lageado, Universidade Estadual "Júlio de Mesquita Filho", Botucatu, SP, Brasil.
Centro APTA Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, SP, Brasil
Genet Mol Res. 2015 Oct 30;14(4):14076-87. doi: 10.4238/2015.October.29.27.
The effect of selection for postweaning weight was evaluated within the growth curve parameters for both growth and carcass traits. Records of 2404 Nellore animals from three selection lines were analyzed: two selection lines for high postweaning weight, selection (NeS) and traditional (NeT); and a control line (NeC) in which animals were selected for postweaning weight close to the average. Body weight (BW), hip height (HH), rib eye area (REA), back fat thickness (BFT), and rump fat thickness (RFT) were measured and records collected from animals 8 to 20 (males) and 11 to 26 (females) months of age. The parameters A (asymptotic value) and k (growth rate) were estimated using the nonlinear model procedure of the Statistical Analysis System program, which included fixed effect of line (NeS, NeT, and NeC) in the model, with the objective to evaluate differences in the estimated parameters between lines. Selected animals (NeS and NeT) showed higher growth rates than control line animals (NeC) for all traits. Line effect on curves parameters was significant (P < 0.001) for BW, HH, and REA in males, and for BFT and RFT in females. Selection for postweaning weight was effective in altering growth curves, resulting in animals with higher growth potential.
在生长和胴体性状的生长曲线参数范围内，评估了断奶后体重选择的效果。分析了来自三个选择品系的2404头内洛尔牛的记录：两个高断奶后体重选择品系，即选择品系（NeS）和传统品系（NeT）；以及一个对照品系（NeC），该品系的动物选择断奶后体重接近平均值。测量了8至20月龄（雄性）和11至26月龄（雌性）动物的体重（BW）、体高（HH）、眼肌面积（REA）、背膘厚度（BFT）和臀脂厚度（RFT），并收集了相关记录。使用统计分析系统程序的非线性模型程序估计参数A（渐近值）和k（生长速率），该程序在模型中纳入了品系（NeS、NeT和NeC）的固定效应，目的是评估各品系间估计参数的差异。对于所有性状，选择的动物（NeS和NeT）比对照品系动物（NeC）表现出更高的生长速率。雄性的BW、HH和REA以及雌性的BFT和RFT的曲线参数的品系效应显著（P < 0.001）。断奶后体重选择有效地改变了生长曲线，产生了具有更高生长潜力的动物。
