Genetic association among scrotal circumference and female reproductive traits in Nellore

[摘要] - The objectives of this work were to estimate of genetic parameters for scrotal circumference (SC) at 12 (SC12, n = 652) and 18 (SC18, n = 607) months of age, age at first calving (AFC, n = 1,582), first (FCD, n = 1,582) and second (SCD, n = 644) calving dates and first calving interval (FCI, n = 644) in Nellore cattle. Parameters were estimated using REML methodology, with animal models and considering the relations among 15,648 animals. Heritability estimates from univariate analyses were .24±.10, .31±.10, .01±.03, .11±.05, .07±.08 and .10±.10, respectively, for SC12, SC18, AFC, FCD, SCD and FCI. These values were close to the estimates from bivariate analyses, except for the analysis including both SC (heritability estimates of .61 and .68, respectively, for SC12 and SC18). Genetic correlation estimates between SC12 and, respectively, AFC, FCD, SCD and FCI were ¾1.00, -.08, -.71, and -.37. In the same order, genetic correlation between SC18 and female reproductive traits were ¾1.00, .21, -.35 and -.44. The selection for SC12 would be more effective than selection for SC18 when trying to improve the reproductive traits of the females.

[学科分类] 兽医学

[关键词] genetic correlation;reproduction     IntroduçãoOs trabalhos disponíveis na literatura brasileira relativos à avaliação da eficiência reprodutiva da fêmea zebu têm enfatizado quase exclusivamente a idade à primeira cria e o intervalo de partos (ANDRADE;1991)