Genetic Parameters Analysis Of Conformation Traits,milk Production Traits And Longevity Traits Of Chinese Holsteins In Ningxia

In this study,the first parity body shape identification recorded of 45,451 Chinese Holstein cows in 44 pastures of Ningxia Helan Mountain Dairy Co.Measurement records and data on longevity traits of 50,169 Chinese Holstein dairy cows in 15 pastures from 2011 to 2021,using single-trait and multi-trait animal models,using DMU software,using the AI-REML combined with the EM algorithm to estimate the genetic parameters of the conformation traits,the heritabilities of milk production traits and longevity traits of dairy cows,and the correlation between conformation traits and these three traits.Statistical analysis obtained the following results:(1)The heritabilities of conformation traits of Holstein dairy cows in Ningxia ranged from 0.11(angularity)to 0.37(heel depth),and most of the conformation traits were medium heritability traits.(2)The genetic correlation between conformation traits of Holstein dairy cows in Ningxia ranged from-0.75(udder depth and angularity)to 0.95(stature and trunk size),and the range of phenotypic correlations between body types was-0.52(udder depth and angularity)to 0.68(height and trunk size).(3)The heritability of milk production traits of Holstein dairy cows in Ningxia ranged from 0.23(SCS)and 0.50(305-d milk yield),except for 305-d milk yield(0.50)which is high heritability,the rest of the milk production traits are moderate heritability.(4)The range of genetic correlation between conformation traits and milk production traits of Holstein dairy cows in Ningxia were-0.31(pin setting and daily milk yield)to 0.34(stature and daily milk yield),-0.33(pin setting and milk fat percentage)to 0.57(udder texture and milk protein percentage),-0.32(pin setting and milk protein rate)～0.38(udder texture and milk protein percentage),-0.43(heel depth and SCS)～0.34(body depth and SCS)and-0.56(hoof Angle and 305-d milk yield)～0.32(body depth and 305-d milk yield).The phenotypic correlation coefficients of milk production traits and conformation traits ranged from-0.13(heel depth and daily milk yield)to 0.14(trunk size and daily milk yield),-0.12(heel depth and milk fat percentage)to 0.24(udder texture and milk fat percentage),-0.13(heel depth and milk protein percentage)～0.10(udder texture and milk protein percentage),-0.13(heel depth and SCS)～0.09(bone texture and SCS)and-0.15(heel depth and 305-d milk yield)～0.33(udder texture and 305-d milk yield).The phenotypic correlation coefficients of most conformation traits and milk production traits were less than 0.10.(5)The heritability of productive life of Holstein dairy cows in Ningxia was 0.02,and the heritability of herd life was 0.03,which were relatively low.(6)The genetic correlation between conformation traits and productive life of Holstein dairy cows in Ningxia ranged from-0.94(fore attachment)to 0.42(rear leg-rear view),and the phenotypic correlations ranged from-0.06(udder depth)to 0.18(angularity).Genetic correlations except body depth(0.10),pin width(0.07),udder depth(-0.18),rear attachment height(-0.08),rear attachment width(-0.18)and angularity(0.18)were less correlated,and the rest of the conformation traits had moderately high correlations with productive life.The genetic correlations between conformation traits and herd life ranged from-0.96(rear attachment width)to 0.86(chest width),and the phenotypic correlations ranged from-0.05(udder depth)to 0.05(angularity).Among them,chest width(0.86),udder depth(0.65),fore teat length(0.68),rear attachment width(-0.96)and rear teat placement(-0.85)had a high genetic correlation with herd life,and hoof angle(-0.04)showed low genetic correlation,and other conformation traits showed moderate genetic correlation with productive life.