Estimation of Breeding Values for Dairy Cattle Using Test-Day Milk Yields

Authors : İbrahim KAYA, Yavuz AKBAŞ, Can UZMAY

Pages : 459-464

View : 16 | Download : 5

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The objectives of this study were to estimate genetic parameters and breeding values for test-day insert ignore into journalissuearticles values(TD); and 305-day milk yields, and to compare the results from TD and 305-day analyses. The data comprised 10,822 TD records from 1103 first lactations of Holstein cows from state farms in the western part of Turkey. Additive genetic, residual and permanent environmental variances, heritabilities and breeding values for 305-day and TD milk yields were estimated by the REML method using animal models. The heritability estimate insert ignore into journalissuearticles values(0.11); of TD milk yields was lower than the corresponding estimate insert ignore into journalissuearticles values(0.25); for 305-day milk yields. The product-moment correlations insert ignore into journalissuearticles values(? 0.97); show that estimated breeding values insert ignore into journalissuearticles values(EBVs); for TD milk yields are closely correlated with EBVs for 305-day milk yields. Spearman and Kendall rank correlations between rankings of animals for EBVs for TD and 305-day milk yields were also high insert ignore into journalissuearticles values(? 0.97 and ? 0.86, respectively);. Shifts in rank for various top lists of cows and sires ranked by their EBVs for 305-day and TD milk yields show that more extreme changes in ranks occurred in cows than in sires. TD milk yields could be used instead of 305-day milk yield for the genetic evaluation of dairy cattle. Furthermore, using TD yields for genetic evaluations offers more advantages.
Keywords : dairy cattle, breeding value, test day milk yields, test day model