摘要：Investigation of genetic parameters and trend of milk and fat yield traits is main goal of this study. This study used 2213 records of first lactation Holstein's dairy cattle of west provinces of Iran for estimate of genetic and phonotype trend. These data get from Animal Breeding Center from 1996-2006 then analyzed. Annual Genetic and phonotype trend for milk and fat yield traits was 19.61, 0.171, 71.99 and 1.401, respectively. Estimation of the variance-covariance traits and hereditability of the traits of milk production and the milk fat content were made using the single trait animal model and the DFREML software. Heritability of milk and fat yield was 21.02±0.06 and 0.086±0.005, respectively. The components of variance additive genetic, phonotypic and error were 505272.69, 2403771.14 and 1806194.70 for milk yield and 185.84, 2256.74 and 2160.98 for fat yield, respectively.
