Koch R M, Cundiff L V, Gregory K E
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
J Anim Sci. 1994 Apr;72(4):864-85. doi: 10.2527/1994.724864x.
Selection in three lines of Hereford cattle for 1) weaning weight (WWL), 2) yearling weight (YWL), and 3) an index of yearling weight and muscle score (IXL) was studied. Remnant foundation cows and semen from seven foundation sires were used to establish an unselected control line for the last 11 yr of the experiment. Performance data collected over a 23-yr period on birth weight (BWT), weaning weight (WWT), postweaning gain (PWG), yearling weight (YWT), muscle score (MSC), and an index (IDX) giving equal weight to standard deviations of yearling weight and muscle score were analyzed. Generation interval of midparents was about 4.16 yr in each selected line. Sire and dam selection differentials, in standard deviation units per generation, for primary criteria were, respectively, 1.59 and .33 for WWT in WWL, 1.75 and .25 for YWT in YWL, and 1.42 and .25 for IDX in IXL. Components of direct and maternal genetic variances, direct-maternal covariance, and dam permanent environmental variance were estimated by REML. The average annual response of males and females in actual units for each trait in WWL, YWL, and IXL was, respectively, BWT, .22, .24, and .27 kg; WWT, .98, .63, and 1.26 kg; YWT, 2.43, 2.64, and 3.44 kg; and MSC, .053, .009, and .104 scores. Average selection responses in BWT, WWT, YWT, MSC, and IDX per unit of primary criteria in each selection line (all in standard deviation units) were .22, .20, .31, .10, and .24 for WWT in WWL; .23, .12, .32, .04, and .21 for YWT in YWL; and .27, .22, .40, .20, and .36 for IDX in IXL. Responses in bold type are realized heritability and others are correlated responses. Realized genetic correlations were .78 for WWT and YWT, .87 for WWT and IDX, and .86 for YWT and IDX. Responses for all traits in IXL were greater than in other selected lines.
研究了对赫里福德牛三个品系进行的选择，选择标准为：1) 断奶体重（WWL），2) 周岁体重（YWL），以及3) 周岁体重和肌肉评分指数（IXL）。在实验的最后11年，使用剩余的基础母牛和7头基础公牛的精液建立了一个未选择的对照品系。分析了在23年期间收集的关于出生体重（BWT）、断奶体重（WWT）、断奶后增重（PWG）、周岁体重（YWT）、肌肉评分（MSC）以及一个对周岁体重和肌肉评分标准差赋予同等权重的指数（IDX）的性能数据。每个选择品系中亲代的世代间隔约为4.16年。每个选择品系中，以标准差单位表示的每代父本和母本选择差，对于WWL中WWT的主要标准分别为1.59和0.33，对于YWL中YWT的主要标准分别为1.75和0.25，对于IXL中IDX的主要标准分别为1.42和0.25。通过REML估计直接遗传方差、母体遗传方差、直接-母体协方差以及母本永久环境方差的组成部分。WWL、YWL和IXL中每个性状的雄性和雌性实际单位的平均年反应分别为：BWT，0.22、0.24和0.27千克；WWT，0.98、0.63和1.26千克；YWT，2.43、2.64和3.44千克；以及MSC，0.053、0.009和0.104分。每个选择品系中（均以标准差单位表示）每单位主要标准在BWT、WWT、YWT、MSC和IDX方面的平均选择反应，对于WWL中WWT分别为0.22、0.20、0.31、0.10和0.24；对于YWL中YWT分别为0.23、0.12、0.32、0.04和0.21；对于IXL中IDX分别为0.27、0.22、0.40、0.20和0.36。加粗字体的反应是实现的遗传力，其他是相关反应。WWT和YWT的实现遗传相关为0.78，WWT和IDX的实现遗传相关为0.87，YWT和IDX的实现遗传相关为0.86。IXL中所有性状的反应均大于其他选择品系。
