Cahaner A, Nitsan Z
Poult Sci. 1985 Jul;64(7):1257-63. doi: 10.3382/ps.0641257.
Three hundred chickens from pedigree matings in a commercial female grandparent stock were slaughtered at 7 or 9 weeks of age. Data were obtained for live body weight and various carcass parts. Coefficients of variation of abdominal fat (g and g/100 g body weight) were above 30%. Coefficients of variation of the weights of muscular and skeletal parts were much lower (about 10%) and were further reduced when calculated per 100 g body weight. Heritability of abdominal fat was higher (.82) than that of live body weight (.55) and parts: breast (.55), thighs (.31), and drumsticks (.51). Phenotypic and genetic correlations between each of the heavier parts (breast, thighs, and drumsticks) and body weight were over .8; for smaller parts (legs, wings, etc.) correlations (.49 to .79) were lower. Abdominal fat showed the lowest correlation (.26 to .36) with body weight. The genetic correlations seemed free of the part-whole relationship. Simultaneous selections for live body weight and for breast weight, or against abdominal fat, were simulated using "independent culling levels". The theoretical calculations showed that adding breast weight as a selection criterion had no advantage over selection for body weight alone due to the high genetic correlation between the two traits. However, simultaneous selection for body weight and against abdominal fat, using optimum combination of culling, was economically superior to selection for body weight alone. The advantage of this two-trait selection depends on the correlation between the traits and their relative values.
从一个商业雌性祖代种鸡的系谱交配中选取300只鸡，在7周或9周龄时进行屠宰。获取了活体体重和各种胴体部位的数据。腹部脂肪（克和克/100克体重）的变异系数超过30%。肌肉和骨骼部位重量的变异系数则低得多（约10%），按每100克体重计算时进一步降低。腹部脂肪的遗传力（0.82）高于活体体重（0.55）和各部位：胸肌（0.55）、大腿（0.31）和小腿（0.51）。每个较重部位（胸肌、大腿和小腿）与体重之间的表型和遗传相关性均超过0.8；对于较小部位（腿部、翅膀等），相关性（0.49至0.79）较低。腹部脂肪与体重的相关性最低（0.26至0.36）。遗传相关性似乎不受部分与整体关系的影响。使用“独立淘汰水平”模拟了对活体体重和胸肌重量同时进行选择，或对腹部脂肪进行反向选择。理论计算表明，由于这两个性状之间的高遗传相关性，将胸肌重量作为选择标准相对于仅选择体重并无优势。然而，使用最佳淘汰组合对体重和腹部脂肪同时进行选择在经济上优于仅选择体重。这种两性状选择的优势取决于性状之间的相关性及其相对值。
