Genetic Analysis of Milk Urea Nitrogen,Milk Production Traits,and Somatic Cell Score in First Lactation of Holstein Cattle
The aim of this study was to study the genetic parameters of milk urea nitrogen and its genetic and phenotypic correlations with milk production traits(milk yield,milk protein percent-age,milk fat percentage)and somatic cell score in Holstein cows in Shandong Province.In this study,we used data from 99 732 DHI records of 15 497 first-calf Chinese Holstein cows in Shan-dong Province between 2016 and 2022,and the effects of farm,calving year,calving season,cal-ving age in months,and stage of lactation were used as fixed effects,and individual additive ge-netic effects as well as permanent environmental effects were used as random effects,the genetic parameters were estimated using the DMU software,and AI-REML combined with the EM algo-rithm with the repetition force model for genetic parameter estimation.The results showed that the heritability of milk urea nitrogen,milk yield,milk fat percentage,milk protein percentage and somatic cell score were 0.129,0.252,0.188,0.257,0.110,respectively,which were low to medium heritability;the repeatability was 0.132,0.513,0.231,0.320,0.339,respectively,which were medium repeatability except for milk urea nitrogen;the genetic correlation between milk urea nitrogen and milk yield,milk fat percentage,milk protein percentage and somatic cell score had genetic correlations of-0.02,0.20,0.04 and-0.11,respectively;and phenotypic correlations of 0.01,0.05,0.01 and-0.015 were near zero,respectively.The results indicate that milk urea nitrogen has a weak genetic and phenotypic correlation with milk production traits and somatic cell score.Therefore,it is feasible to select for milk urea nitrogen without adversely affecting milk production traits,as well as incorporating it into Holstein cattle breeding efforts
万方数据
维普
