Adjustment for heterogeneity of variance for milk yield among herds of Holstein cattle in Brazil

Revista Brasileira de Zootecnia

Pereira, Carmen Silva³  Penna, Vânia Maldini³  Torres, Robledo de Almeida²  Valente, José¹  Torres Filho, Rodolpho de Almeida²  Costa, Claudio Nápolis¹  Bergmann, José Aurélio Garcia³ 

[1] EMBRAPA;UFV;UFMG

关键词: dairy cows;    genetic correlation;    variance heterogeneity;    genetic parameters;    milk yield    IntroduçãoAs diferenças entre os rebanhos na variabilidade da produção;    geralmente;    têm sido atribuídas às diferenças nos fatores climáticos locais ou regionais e nos tipos de manejo do rebanho;    este último incluindo fatores como intensidade e quantidade de alimentação de acordo com a produção;    o estado sanitário do rebanho e a qualidade dos animais de reposição;   

DOI  :  10.1590/S1516-35981999000200012

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

Data of 36,755 first lactation of Holstein cows, daughters of 866 sires, distributed in different states from 1980 to 1993, were stratified in herds according to the phenotypic standard deviation of the milk yield adjusted for adult age, in three levels: low (11,713 lactations), medium (12,764 lactations) and high (12,278 lactations). The total milk production adjusted for adult age and adjusted for adult age and for 305 days of lactation, within each class, and the base 10 logarithm transformations, square root, standardization and the division by class phenotypic standard deviation were analyzed. The averages of milk yield, the genetic, residual, and phenotypic variance components increased with the increase of the class mean standard deviation. The heritability did not have the same behavior, the heritability estimates of the traits of the class with high standard deviation were similar to the heritability of traits of class with low standard deviation, and both were smaller than the class with medium standard deviation, although the component of addictive genetic variance has been higher. The used transformations did not correct the existing heterogeneity of variance among the classes. The heritabilities of the unchanged characteristics varied from .25 to .35.

【 授权许可】

CC BY-NC