Pariacote F, Van Vleck L D, Hunsley R E
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
J Anim Sci. 1998 Oct;76(10):2584-8. doi: 10.2527/1998.76102584x.
Carcass measurements were taken on 1,292 steers and collected by the American Shorthorn Association. The sires were purebred or appendix-registered Shorthorn. Because all dams were not Shorthorn, genetic fractions of breeds of origin were determined for each dam. Measurements for hot carcass weight; dressing percentage; fat thickness; ribeye area; kidney, pelvic, and heart fat (KPH); marbling; and yield grade were analyzed jointly with a multivariate REML algorithm to estimate heritabilities of and genetic and phenotypic correlations among the traits. The sire model chosen as best fit of the data included fixed effects of herd of origin (377 classes), slaughter group (118 classes), year of birth (1979-1995), and covariates for linear effects of genetic fractions of breeds (13) of dam and slaughter age, with sire (n=409) as a random effect. Estimates of heritability were .60+/-.19, .49+/-.19, .46+/-.19, .97+/-.21, .45+/-.19, .88+/-.21, and .54+/-.19 for previous order of traits, respectively. Most genetic correlations were not significantly different from zero. Genetic correlations of hot carcass weight were significant and positive with dressing percentage (.65+/-.19) and with ribeye area (.70+/-.14). Dressing percentage was significantly positively genetically correlated with ribeye area (.79+/-.16) and negatively genetically correlated with yield grade (-.56+/-.29). Yield grade was also significantly negatively genetically correlated with ribeye area (-.85+/-.10) and positively genetically correlated with fat thickness (.67+/-.15). Most phenotypic correlations were significant and positive. Only the phenotypic correlations of dressing percentage with marbling and with yield grade, and ribeye area with KPH and with marbling were not significantly different from zero. Significant negative correlations were fat thickness with ribeye area (-.16+/-.04) and ribeye area with yield grade (-.61+/-.03). Results seem to indicate that genetic antagonisms between quantity and quality traits were small to moderate. Thus, the opportunity seems to exist for breeding plans to improve carcass quality without having any adverse genetic effect on hot carcass weight, dressing percentage, or ribeye area. The high heritability observed for marbling indicates that a low genetic potential for marbling can be remedied by selection within breed.
对1292头阉牛进行了胴体测量，并由美国短角牛协会收集数据。这些公牛为纯种或附录注册的短角牛。由于并非所有母牛都是短角牛，因此确定了每头母牛的品种遗传比例。对热胴体重、屠宰率、脂肪厚度、眼肌面积、肾周、盆腔和心脏脂肪（KPH）、大理石花纹和产量等级的测量数据，采用多变量REML算法进行联合分析，以估计这些性状的遗传力以及性状间的遗传和表型相关性。被选为最适合数据的父系模型包括原产地牛群（377个类别）、屠宰组（118个类别）、出生年份（1979 - 1995年）的固定效应，以及母牛品种遗传比例（13种）和屠宰年龄线性效应的协变量，将公牛（n = 409）作为随机效应。各性状遗传力估计值分别为：热胴体重0.60±0.19、屠宰率0.49±0.19、脂肪厚度0.46±0.19、眼肌面积0.97±0.21、KPH 0.45±0.19、大理石花纹0.88±0.21、产量等级0.54±0.19。大多数遗传相关性与零无显著差异。热胴体重与屠宰率（0.65±0.19）和眼肌面积（0.70±0.14）的遗传相关性显著且为正。屠宰率与眼肌面积（0.79±0.16）的遗传相关性显著为正，与产量等级（-0.56±0.29）的遗传相关性显著为负。产量等级与眼肌面积（-0.85±0.10）的遗传相关性也显著为负，与脂肪厚度（0.67±0.15）的遗传相关性显著为正。大多数表型相关性显著且为正。只有屠宰率与大理石花纹、屠宰率与产量等级、眼肌面积与KPH、眼肌面积与大理石花纹的表型相关性与零无显著差异。脂肪厚度与眼肌面积（-0.16±0.04）以及眼肌面积与产量等级（-0.61±0.03）存在显著负相关。结果似乎表明，数量性状和质量性状之间的遗传拮抗作用较小到中等。因此，似乎有机会制定育种计划来提高胴体品质，而不会对热胴体重、屠宰率或眼肌面积产生任何不利的遗传影响。观察到的大理石花纹的高遗传力表明，通过品种内选择可以弥补大理石花纹的低遗传潜力。
