Boligon A A, Vicente I S, Vaz R Z, Campos G S, Souza F R P, Carvalheiro R, Albuquerque L G
J Anim Sci. 2016 Dec;94(12):5014-5022. doi: 10.2527/jas.2016-0737.
Principal component analysis was applied to evaluate the variability and relationships among univariate breeding values predicted for 9 weaning and yearling traits, as well as suggest functions of the traits that would promote a particular breeding objective. Phenotypic and pedigree information from 600,132 Nelore animals was used. Genetic parameters and breeding values were obtained from univariate analyses of birth to weaning weight gain; weaning to yearling weight gain; conformation, finishing precocity, and muscling scores at weaning and at yearling; and yearling scrotal circumference. The principal component mainly associated with maturity (precocious vs. late animals) was used as a pseudophenotype in bivariate analyses with either adult weight or adult height of cows. Direct heritability estimates ranging from 0.19 ± 0.01 to 0.41 ± 0.01 indicate that these 9 traits are all heritable to varying degrees. Correlations between the breeding values for the various traits ranged from 0.14 to 0.88. Principal component analysis was performed on the standardized breeding values. The first 3 principal components attained the Kaiser criterion, retaining 48.06%, 18.03%, and 12.97% of the total breeding value variance, respectively. The first component was characterized by positive coefficients for all traits. The second component contrasted weaning traits with yearling traits. The third component represented a contrast between late maturity animals (better for weight gain and conformation) and early maturity animals (better for finishing precocity, muscling, and scrotal circumference). Thus, the first 3 components represent 3 different potential selection criteria. Selecting for the first principal component would identify animals with positive breeding values for all studied traits. The second principal component may be used to identify animals with higher or lower maturation rates (precocity). Animals with negative values in the third principal component are regarded as early maturing. Genetic correlations between maturity (third principal component) with adult weight and adult height were 0.19 ± 0.02 and 0.32 ± 0.02, respectively. These results showed that the weaning and yearling bovine maturity is genetically associated with the adult size of the cows used in reproduction.
主成分分析用于评估预测的9个断奶和周岁性状的单变量育种值之间的变异性和关系，并提出有助于实现特定育种目标的性状函数。使用了来自600,132头内洛尔牛的表型和系谱信息。遗传参数和育种值通过对出生至断奶体重增加、断奶至周岁体重增加、断奶和周岁时的体型、育肥早熟性和肌肉评分以及周岁阴囊周长进行单变量分析获得。在与成年母牛体重或成年母牛身高的双变量分析中，将主要与成熟度（早熟与晚熟动物）相关的主成分用作伪表型。直接遗传力估计值在0.19±0.01至0.41±0.01之间，表明这9个性状都具有不同程度的遗传性。各性状育种值之间的相关性在0.14至0.88之间。对标准化育种值进行主成分分析。前3个主成分达到了凯泽准则，分别保留了总育种值方差的48.06%、18.03%和12.97%。第一个成分的所有性状系数均为正。第二个成分将断奶性状与周岁性状进行了对比。第三个成分代表了晚熟动物（增重和体型较好）与早熟动物（育肥早熟性、肌肉和阴囊周长较好）之间的对比。因此，前3个成分代表了3种不同的潜在选择标准。选择第一个主成分将识别出所有研究性状育种值为正的动物。第二个主成分可用于识别成熟率较高或较低（早熟性）的动物。第三个主成分中值为负的动物被视为早熟。成熟度（第三个主成分）与成年体重和成年身高的遗传相关性分别为0.19±0.02和0.32±0.02。这些结果表明，断奶和周岁牛的成熟度与用于繁殖的成年母牛的体型在遗传上相关。
