宁夏地区荷斯坦牛青年牛繁殖性状遗传参数估计

旨在探究青年牛繁殖性状遗传能力群体遗传参数，评估不同配种季节间青年牛繁殖性状基因型与环境的互作效应（G×E）。本研究利用宁夏地区12个牧场2007—2019年荷斯坦牛繁殖事件信息记录，计算青年牛繁殖性状包括：首配日龄（AFS）、初产日龄（AFC）、首次配种后56天不返情率（NRR56）、首末次配种间隔（IFL）、妊娠期长短（GL）和首次配种受胎率（CR）共30 645~44 888条表型值数据。通过DMU软件的DMUAI模块使用单性状动物模型估计性状遗传力，使用双性状动物模型估计性状间遗传相关和不同配种季节间同一繁殖性状的基因型与环境互作程度（不同环境下同一性状间的遗传相关，r）。结果表明，AFS遗传力为0.483±0.013，AFC遗传力为0.231±0.015，青年牛NRR56、IFL、GL、CR遗传力及标准误分别为0.031±0.007，0.038±0.008，0.216±0.017和0.031±0.007；青年牛IFL、GL与AFC间有显著正相关（IFL-AFC：0.812±0.019，P<0.05；GL-AFC：0.119±0.053，P<0.05），NRR56和CR与AFC间有显著负相关（NRR56-AFC：-0.274±0.086，P<0.05；CR-AFC：-0.532±0.065，P<0.05）。除IFL在夏季与秋季间和CR、NRR56、IFL在秋季与冬季间无基因型与环境互作效应外（r>0.8），CR、NRR56、IFL在其他季节间均存在基因型与环境互作效应（r<0.8）。在CR中，春季配种与冬季配种间的遗传相关最低，在NRR56、IFL中则是春季配种与秋季配种的遗传相关最低。结果显示，青年牛生长发育能力和妊娠维持能力具有较大遗传选育潜力，而受胎能力易受环境影响。青年牛繁殖性状的遗传表现存在基因型与环境互作效应。因此，在进行遗传评定时需要考虑配种时的气候环境差异，优化评估模型以提高育种实践中遗传选育的准确性。

Estimation of Genetic Parameters of Reproductive Traits of Holstein Heifers in Ningxia

The study aimed to explore the population genetic parameters of reproductive traits of heifers and evaluate the genotype-by-environment interaction(G×E)effect for heifer fertility between different inseminate seasons.The reproductive information of Holstein cows from 12 farms in Ningxia from 2007 to 2019 was used.Totally 30645-44888 heifer reproductive phenotypic records were obtained,including age at first service(AFS),age at first calving(AFC),56-days non-return rate of first insemination(NRR56),interval from first to last inseminations(IFL),gestation length(GL)and conception rate of first insemination(CR).Then,a single-trait animal model was used to obtain heritability of each trait and a bi-variate animal model was also applied to estimate genetic correlations between traits and G×E interaction degree between insemination seasons(genetic correlation of the same trait between different environments,r)with the DMUAI module of DMU.The results showed that the heritabilities and their standard error of heifer reproductive traits were:0.483±0.013,0.231±0.015,0.031±0.007,0.038±0.008,0.216±0.017 and 0.031±0.007 for AFS,AFC,NRR56,IFL,GL and CR,respectively.IFL and GL was significantly and positively correlated with AFC(IFL-AFC:0.812±0.019,P<0.05;GL-AFC:0.119±0.053,P<0.05);NRR56 and CR were significantly and negatively correlated with AFC(NRR56-AFC:-0.274±0.086,P<0.05;CR-AFC:-0.532±0.065,P<0.05).Except for IFL in summer-autumn pair and CR,NRR56,IFL in autumn-winter pair(r>0.8),CR,NRR56,IFL had G×E interaction effects(r<0.8)in other season pairs.For CR,the lowest correlation coefficient was observed for insemination between spring and winter,while the genetic correlation for insemination between spring and autumn was the lowest for NRR56 and IFL.The result indicate that the growth and pregnancy maintenance ability of heifers have preferential genetic selection potential,while the conception ability of heifer is affected largely by environment.It is necessary to take climate condition differences into consideration when heifer fertility traits are genetically evaluated due to the existence of G×E,and use more suitable models to improve the accuracy of genetic selection in breeding practices.