不同选择指数对中国荷斯坦种公牛综合育种值排名的影响

Impact of Selection Index on the Rank of Chinese Holstein Bulls

本研究旨在探讨包含不同性状的综合选择指数对荷斯坦种公牛排队的影响。收集了全国199个牛场的664 284头荷斯坦牛产奶量、乳脂率、乳蛋白率、乳脂量、乳蛋白量、体细胞数以及35 281头荷斯坦牛的体型性状。然后采用多性状动物模型BLUP法预测生产性状和体型性状的育种值,计算3种不同综合选择指数下47头种公牛的综合育种值,并对其排队进行了比较。结果显示,使用包含产奶量、乳脂率、乳蛋白率、体细胞评分4个性状的综合选择指数(TMI1)和包含乳脂量、乳蛋白量、体细胞评分3个性状的综合选择指数(TMI2)对公牛的排队一致性很高,秩相关为0.94;只包含生产性状的综合选择指数(TMI1、TMI2)和加入了体型性状的综合选择指数(TMI3)对公牛的排队差异很大,秩相关分别为0.76和0.67。这些结果提示,乳脂量、乳蛋白量可以替代产奶量、乳脂率、乳蛋白率纳入综合选择指数,体型性状进入综合选择指数对评价种公牛综合遗传素质具有重要作用。

The aim of this study was to investigate the impact of selection indexes involving different traits on the rank of Chinese Holstein bulls.The performance data of various traits including milk yield,fat yield,protein yield,fat percentage,protein percentage,SCS,and type classification,were collected and the final data set contained 664284 cows and 199 herds.Breeding values were predicted by multiple-trait animal model BLUP method.Three selection indexes（namely TM1,TM2 and TM3）were calculated for 47 sires using breeding values.The selection index TM1 that contains four production traits（milk yield,fat percentage,protein percentage,and SCS）showed high consistency with TMI2 consisting of three traits（fat yield,protein yield,and SCS）,with the Spearman＇s rank correlation coefficient（rs）=0.94.The rank of sires based on TMI3 that contains production traits and type traits was quite different from those based on TMI1 and TMI2,with rs=0.76 and 0.67,respectively.These results suggested that the percentage traits could be replaced by the yield traits,and the type traits played an important role for the genetic evaluation of Holstein bulls.