Kahi A K, Oguni T, Sumio Y, Hirooka H
Animal Breeding and Genetics Group, Department of Animal Sciences, Egerton University, Njoro, Kenya.
J Anim Sci. 2007 Feb;85(2):348-55. doi: 10.2527/jas.2005-657.
The objectives of this study were 1) to examine the genetic relationship between growth and carcass traits and carcass price (CaP) and profitability in Japanese Brown cattle, 2) to estimate economic values of carcass and growth traits as regression coefficients of price and profit traits on growth and carcass traits using a multiple regression model, and 3) to compare direct and indirect predictions of the genetic merit of profit obtained from multitrait analysis and selection index, respectively. Growth and carcass traits considered in this study were ADG during the feedlot period, CWT, LM area (LMA), rib thickness (RT), subcutaneous fat thickness (SFT), and marbling score (MS). Carcass price was evaluated as a price trait independent of its influence on profit. Profit traits were defined as 1) net income per year (PROF1), 2) net income per year/energy requirement (PROF2), and 3) net income per year minus feed costs (PROF3). Correlations between direct and indirect predictions were estimated based on EBV of sires and dams with progeny records. The heritability estimate for CaP was 0.41. The heritability estimates for profit traits were high and were 0.62, 0.66, and 0.60 for PROF1, PROF2, and PROF3, respectively. The genetic correlations between CaP and ADG, CWT, LMA, RT, SFT, and MS were 0.19, 0.14, 0.30, 0.38, -0.11, and 0.98, respectively. Among the profit traits, PROF1 had the greatest genetic correlations with growth and carcass traits. The correlations with ADG, CWT, LMA, RT, SFT, and MS were 0.30, 0.21, 0.24, 0.39, -0.01, and 0.69, respectively. These estimates indicate that use of profit traits as a selection criterion may promote desirable correlated responses in growth and carcass traits. The economic values for growth and carcass traits estimated relative to CaP and each profit trait differed because of the apparent differences in the description of these traits. The correlations between EBV for the same profit traits from direct and indirect predictions were high and ranged from 0.818 to 0.846 based on EBV of sires and from 0.786 to 0.798 based on EBV of dams. The strong correlations between direct and indirect predictions for profit indicate that there is no advantage to selecting directly for profit compared with an index with all of the component traits.
1）研究日本褐牛生长性状、胴体性状与胴体价格（CaP）及盈利能力之间的遗传关系；2）使用多元回归模型估计胴体和生长性状的经济价值，作为价格和利润性状对生长和胴体性状的回归系数；3）比较分别从多性状分析和选择指数获得的利润遗传 merit 的直接和间接预测。本研究中考虑的生长和胴体性状包括育肥期平均日增重（ADG）、胴体重（CWT）、眼肌面积（LMA）、肋骨厚度（RT）、皮下脂肪厚度（SFT）和大理石花纹评分（MS）。胴体价格被评估为一个独立于其对利润影响的价格性状。利润性状定义为：1）每年净收入（PROF1）；2）每年净收入/能量需求（PROF2）；3）每年净收入减去饲料成本（PROF3）。基于具有后代记录的父系和母系的估计育种值（EBV），估计直接和间接预测之间的相关性。CaP 的遗传力估计值为 0.41。利润性状的遗传力估计值较高，PROF1、PROF2 和 PROF3 的遗传力分别为 0.62、0.66 和 0.60。CaP 与 ADG、CWT.LMA、RT、SFT 和 MS 的遗传相关性分别为 0.19、0.14、0.30、0.38、-0.11 和 0.98。在利润性状中，PROF1 与生长和胴体性状的遗传相关性最大。与 ADG、CWT、LMA、RT、SFT 和 MS 的相关性分别为 0.30、0.21、0.24、0.39、-0.01 和 0.69。这些估计表明，将利润性状用作选择标准可能会促进生长和胴体性状中理想的相关反应。相对于 CaP 和每个利润性状估计的生长和胴体性状的经济价值因这些性状描述的明显差异而不同。基于父系 EBV，相同利润性状的直接和间接预测的 EBV 之间的相关性较高，范围为 0.818 至 0.846；基于母系 EBV，相关性范围为 0.786 至 0.798。利润的直接和间接预测之间的强相关性表明，与选择具有所有组成性状的指数相比，直接选择利润没有优势。
