Bailey D R, Gilbert R P, Lawson J E
Agriculture Canada Research Station, Lethbridge, Alberta.
J Anim Sci. 1991 Jun;69(6):2403-12. doi: 10.2527/1991.6962403x.
Two unselected herds of purebred Hereford and Angus cattle were created and their progeny evaluated during a 4-yr period (1964 to 1967) for 168-d postweaning gain when they were fed either a high- or medium-energy diet. Birth weight and 200-d adjusted weaning weight also were measured and the importance of sire x diet interactions for postweaning gain examined. Year effects were significant (P less than .001) for all traits in Herefords and for postweaning gain in Angus. Postweaning gain of both breeds increased in successive years, but no trend was observed for birth and 200-d weights. Bulls were heavier than heifers (P less than .05) for all three traits in both breeds. Hereford and Angus calves receiving the high-energy diet gained more (P less than .001) than their contemporaries fed the medium-energy diet. Sire differences were significant for birth weight in Herefords and for all three traits in Angus. Sire x diet interactions were not significant for postweaning gain in either breed. Genetic correlations were calculated by two methods: the two-way ANOVA approach using sire and sire x diet interaction variance components and the one-way ANOVA approach in which gains by progeny of each sire on each diet were considered to be two distinct traits. The genetic correlations for gain in Herefords could not be estimated by either method because of negative sire variance component estimates. The genetic correlations for gain in Angus were 1.08 for the two-way ANOVA method and 1.43 +/- .64 for the one-way ANOVA method. These results indicate that sires ranked the same based on progeny performance when fed either diet.
创建了两个未经挑选的纯种赫里福德牛群和安格斯牛群，并在4年期间（1964年至1967年）对它们的后代进行评估，测定它们在采食高能或中能日粮时168天断奶后增重情况。同时测量出生体重和200天校正断奶体重，并研究父本×日粮互作对断奶后增重的重要性。年份效应在赫里福德牛的所有性状以及安格斯牛的断奶后增重方面均极显著（P＜0.001）。两个品种的断奶后增重在连续几年中均有所增加，但出生体重和200天体重未观察到趋势。两个品种的所有三个性状中，公牛均比母牛重（P＜0.05）。采食高能日粮的赫里福德和安格斯犊牛比采食中能日粮的同代犊牛增重更多（P＜0.001）。父本差异在赫里福德牛的出生体重以及安格斯牛的所有三个性状方面均显著。父本×日粮互作对两个品种的断奶后增重均不显著。遗传相关性通过两种方法计算：使用父本和父本×日粮互作方差分量的双向方差分析方法，以及将每个父本在每种日粮下后代的增重视为两个不同性状的单向方差分析方法。由于父本方差分量估计值为负，两种方法均无法估计赫里福德牛增重的遗传相关性。对于安格斯牛增重，双向方差分析方法的遗传相关性为1.08，单向方差分析方法为1.43±0.64。这些结果表明，无论饲喂何种日粮，根据后代性能对父本进行的排名相同。
