Evaluation of Genetic and Non Genetic Factors Affecting Reproductive Performance on Holstein Dairy Cows of Isfahan

ABSTARCT The objective of this study was to analyze the effects of factors affecting reproductive traits in the Holstein population of the Isfahan dairy farms for subsequent compilation of the model for genetic evaluation as well as for herd management practice. A data set containing 99012 records were analyzed by a linear model with fixed effects of year , herd ,season, parity of dam, calving interval, age at first calving, period from calving to first insemination, service per consumption. All these effects were not significant; also their appropriate categorization was considered. Analyses of additional factors such as gestation length, age at first calving and service per consumption were performed. The results revealed that gestation length was in a relationship with Holstein dairy cow’s performance. Data for the calving interval (day) showed that the mean of calving interval in experimental animal is 390.43±58.88 and period of lactation was significant effect on calving interval. In this study the mean period of calving to first insemination was 63.64±21.28 days. Data showed that different levels of fixed effects also affecting reproductive traits on Holstein dairy cow. The effect of herd, year and season were significant for those traits. In addition the effect of parity was also significant on calving interval and period of gestation and services per conception. We demonstrated that the additive variance, fixed environmental variance, remained variance and phenotypic variance for this trait were 0.25, 4.54, 2.15 and 2.40 respectively. Also the variance components for age at the first calving were 33.59, 3203.14, 3263.73 and 0.01 for additive variance, remained variance and phenotypic variance respectively. It is obviously that genetic and non genetic factors be must adjusted for the factors that they could improve the performance of Holstein dairy cows.