Estimation of genetic parameters for some production and reproduction traits in a herd of Holstein cow

In this research، a set of 1300 records belonging to 480 Holstein cows reared in dairy herd of agriculture faculty، Mashhad was used. The records were collected from 1985 to 1998 (14 years). For estimation heritability and genetic correlation animal model was fit to the data. The production traits were lactation milk yield، milk yield at peak time and average daily milk yield. The reproduction traits were gestation length، open days and calving interval. Genetic and environmental variances and covariances were estimated by DFREML software. The heritability estimates were 0. 276 (SE=0. 05)، 0. 215 (SE=0. 05) and 0. 311 (SE=0. 06) for production traits and 0. 173 (SE=0. 04)، 0. 085 (SE=0. 02) and 0. 059 (SE=0. 03) for reproduction traits، respectively. Average daily milk yield had positive genetic correlations with milk yield at peak time (0. 13) and lactation milk yield (approximately 1) indicating that average daily milk yield could be used for genetic selection. With respect to low heritability of reproduction traits، environmental improvement could results in increasing fertility performance in the herd under consideration.