Analysis And Evaluation Of The Milk Production And Fertility Traits Of Holstein Herds In Wuhan

In this study, 1771 reproduction and milk performance records of 963 Holstein cows during 1~10 lactations from 2006 to 2014(including 30254 milk yield records, 28169 fat percentage records, 24562 protein percentage records and 1568 calving interval records from 2009 to 2014) were collected in Wuhan Yangtze farm, and the pedigree records of all dams and most sires were collected as well. We implemented the least square variance analysis to analyze the effect of parity, calving season, calving year and first calving age on 305 d milk yield, fat percentage, protein percentage and calving interval. According to the significance test result, fixed factors were selected in the animal model for BLUP, and then genetic parameters(heritability, repeatability and genetic correlation) and fixed effects were calculated using MTDFREML software. The results were as following:1. Parity had highly significant effect on 305 d milk yield, protein percentage and calving interval(P<0.01), significant effect on fat percentage(P<0.05); Calving season had highly significant effect on 305 d milk yield and fat percentage(P<0.01), significant effect on protein percentage and calving interval(P<0.05); calving year had highly effect on 305 d milk yield, fat percentage, protein percentage and calving interval(P<0.01); first calving age had highly significant effect on 305 d milk yield and calving interval(P<0.01), no significant effect on the fat percentage and protein percentage(P>0.05); 305 d milk yield had highly significant effect on calving interval(P<0.01).2. The heritability of 305 d milk yield, fat percentage, protein percentage and calving interval were 0.25, 0.18, 0.13, 0.03; the repeatability were 0.28, 0.35, 0.33, 0.09, respectively.3. 305 d milk yield was moderate negatively correlated(-0.41~-0.32) with fat percentage and protein percentage, and positively correlated(0.33) with calving interval. Calving interval was in weak positive correlation with fat percentage and protein percentage.4. The phenotypic and genetic level for 4 traits of the herds rise in volatility from 2006 to 2014. especially from the herds take DHI test of Hubei province, the phenotypic and genetic levels of milk yield and protein percentage rise steadily. It explains why the DHI had an significant impact on genetic improvement of the herds.