Genetic Evaluation Of Chinese Holstein And Xinjiang Brown Cattle Based On The Test Day Model

The purpose of this study was to establish the genetic evaluation system of Xinjiang area Chinese Holstein lactation performance.DHI daily records of 928168 were collected for the genetic evaluation of Chinese Holstein and Xinjiang brown cattle,and the progeny-testing of Chinese Holstein bulls..Using SAS 8.1 to analyze the effect of non genetic factors,fix effects division;fitting lactation curve of different model and sieve the optimal model for the selected polynomial lactation curve data set Using the DMUAI module of DMU Software(v6.0)combined with stochastic regression model to estimate variance components,the random regression model to field test day and calving season for year fixed effects,with fixed regression calving month effect,random effects include additive genetic and permanent environmental effect.According to the daily model of the 3 parity optimal determination of each trait,the variance component was estimated and the linear/rank correlation(genetic correlation)was calculated for the breeding value of each trait.The CPI2 of the bulls / cows was calculated and ranked to select the top 1000 Chinese Holstein cows as the dynamic core group.The results shows as below:(1)The breed had extremely significant effect on milk protein percentage,lactose percentage,milk total solids content and somatic cell score(P<0.01),and significant effect on the daily milk yield,milk fat percentage,milk fat yield and milk protein percentage(P<0.05);Field and calving years had extremely significant effect on daily milk yield and determination indexes of DHI(P<0.01);and the calving seasons and lactation days had extremely significant effect on other traits except the milk urea nitrogen(P<0.01).(2)Polynomial model is the best fit model of the Chinese Holstein and Xinjiang brown cattle of different paritys.(3)The CPI2 of cows with estimated breeding value for three fetuses are ranked to get the first 1000 individuals as the dynamic core group..The CPI2 of bulls with estimated breeding value for three fetuses are ranked to get the first 50 individuals,which completed the progeny-testing and provides data support for the sales of frozen semen.