Quantitative and genetic analysis of weights at 8, 12, 18 and 24 months of age in a Guzerat breed herd

Revista Brasileira de Zootecnia

Mucari, Talita Buttarello²  Oliveira, João Ademir de¹ 

[1] UNESP, Jaboticabal;Universidade Federal de São Carlos, Itápolis

关键词: genetic correlation;    genetic trend;    guzerat;    heritability;    rank correlation;    weight  Introdução A produção animal pode ser aumentada;    além de via outras formas;    alterando-se a constituição genética dos animais por meio de seleção genética;   

DOI  :  10.1590/S1516-35982003000700009

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

The objective of this study was to estimate heritabilities, genetic correlations, genetic trends and rank correlations of the bulls, for weights at 8, 12, 18 and 24 months of age, in the Guzerat herd from UNESP Campus, Ilha Solteira, SP. The heritabilities and the breeding values were estimated by animal model, using the MTDFREML computational program. The genetic correlations (Pearson) and the rank correlations (Spearman) were obtained by SAS CORR procedure, using the animal breeding values, while the genetic trends were calculated by SAS' REG procedure, using the annual average of the referred breeding values. The statistic model for genetic analysis included fixed effects of contemporary groups and age of cow at calving as covariable (linear and quadratic effects) and random effects: direct additive genetic, maternal genetic, permanent environmental of the cow and residual. The heritabilities for the direct genetic effects were .14, .08, .08 and .13, and for maternal effects were: .01, .02, .02 and .05, respectively, for weights at 8, 12, 18 and 24 months of age. The estimates of the genetic correlation coefficients were positive and of high magnitude, among all studied weights. The annual genetic trends were low and significant only for the weights at 8 and 18 months of age. The rank correlations of the bulls were moderate and significant, indicating reasonable maintenance of rank position of the bulls, when the studied weights were, two by two, compared.

【 授权许可】

CC BY-NC