برآورد فراسنجه‌های ژنتیکی صفت لنگش و ارتباط آن با صفات تولید شیر در گاوهای هلشتاین ایران

In this study, estimation of genetic parameters of Lameness and genetic and phenotypic correlations between Lameness and milk, fat and protein yield were performed. The data obtained from 63403 Holstein cows were collected from the Animal Breeding Center of Iran between 2001 to 2013 Estimation of genetic parameters for lameness was performed by univariate animal and Threshold models. Also, estimation of genetic and phenotypic correlations between Lameness and production traits was performed by bivariate animal model by using the ASREML Software. Results showed that heritability of Lameness with Animal and Threshold models were 0.02 and 0.057, respectively. Estimated heritabilities with two methods were low, but with Threshold model were more than linear model, also genetic correlations between Lameness and persistency of milk, fat and protein yield were 0.31, 0.23 and 0.27, respectively and phenotypic correlations between Lameness and persistency of milk, fat and protein yield were 0.048, 0.037 and 0.029, respectively. Positive correlations between Lameness and production traits show that long term selection for production traits could be the most important factor for culling by Lameness disorders.