Genetic Analysis Between Type Traits, Milk Production Traits、SCS And Longevity Traits Of Holstein Cattle In Shanghai

In recent years,the breeding industry of dairy cattle put more emphasis on increasing milk production.It has lead to the decrease of economic benefits of the dairy industry to some extent,following by a deterioration of milk quality traits,health traits and longevity of cows.So we should not only maintain high milk yield of dairy cows at the same time,but also take composition of milk,breast health and longevity of cows into breeding objectives to obtain maximum economic efficiency.Relationship between linear type traits and milk production traits,mastitis resistance and longevity traits are analysed,to provide some valuable information about genetic improvement of Holstein dairy cattle herd in Shanghai.Data were collected from Shanghai dairy breeding center,containing 4252 records of linear type traits in 30 herds from 2007-2012,In total,44,118 test day records of DHI for 4252 cows.In addition,herd life and function life of 2768 cows were recorded.Genetic parameters(heritability and genetic correlations)of milk production traits,somatic cell score(SCS)and longevity traits(herd life and production life)of Holstein dairy cattle in Shanghai were estimated using single trait and multiple traits animal model with AIREML(average information of restricted maximum likelihood)algorithm through ASReml-R.Based on the genetic statistical analysis,here were the results:1.Overall,there is a gap between body type in Shanghai region with the ideal score.The average score of the 23 linear type traits varied from 4.23(heel depth)～6.84(body depth).Heritability of type traits ranged between 0.09(pin setting)～0.64(bone quality).Mean for final score was 79.61 ±2.28,besides,the heritability of final score was 0.20,standard error was 0.03.2.Estimated heritability of milk production traits(milk yield,fat percentage,protein percentage)and somatic cell score(SCS)was moderate to strong,ranged between 0.19 and 0.47,SCS was the smallest among them,which was 0.19.Phenotypic and genetic correlation between 305d milk yield and fat percentage,protein percentage,SCS were both negative,however,moderate or high positive genetic correlation were found between fat percentage and protein percentage.Stronger positive genetic correlation were estimated for milk yield traits and udder traits;genetic correlations between body stature,feet and legs and milk production traits were mostly negative,while they were mostly positive genetic correlated with fat percentage and protein percentage.3.The herd life of dairy cows mean time period from birth to culling,while,the length of productive life is the time period between first calving and culling.As expected,the heritability of herd life was found to be quite small(0.06),as was its standard error(0.02).Heritability of productive life was a little high,which was 0.10±0.03.The genetic correlation between linear type traits and herd life varied from-0.35(pin width)to 0.55(front end),ranged between-0.50(median suspensory)and 0.38(loin strength)for productive life,respectively.In general,correlation between linear type traits and productive life traits were found negetive this study.