多性状BLUP法估计乳用种公牛育种值及预测精确度分析

最优线性无偏预测（BLUP）法是近代选择乳用种公牛的一种最佳方法，并具有广泛的适用性。本文是在多性状BLUP法基础上，吸收总性能指数（TPI）法的优点，提出公牛多性状传递力指数（TTI）计算公式，应用于种公牛的选择。这种多性状选择方法，我们称为总传递力指数法（简称TTI法）。对BLUP法预测精确度的计算也作了具体说明，并以江西省畜牧良种场13头公牛的579头女儿牛的第一胎产奶资料，其中540头女儿牛有一胎平均乳脂率，464头有一胎时外貌评分记录，应用TTI法对这些公牛的三个性状进行综合评定及其预测精确度分析。TTI法可把经济性状和非经济性状结合在一起，综合评定乳用种公牛，克服了目前局限于单性状的缺陷。本试验结果表明，TTI法在生产上具有较大实用价值，可以在奶牛改良中推广。

MULTI-TRAIT BLUP METHOD ESTIMATES DAIRY SIRES' BREEDING VALUES AND THEIR PREDICTED ACCURACIES

Best Linear Unbiased Prediction (BLUP) is the best method of dairy sire evaluation nowadays, and has a property of general flexibility. Based on Multi-Trait BLUP, absorbing the merits of Total Performance Index (TPI) method, a Total Transmitting Index (TTI) method was developed in this paper. Predicted accuracies of BLUP were explained and calculated in detail. Data of examples in this paper were based on 305-day milk yields of 1st lactation of 579 daughters, where 540 daughters had average fat percentages, 464 daughters had total appearence scores, of 13 black-white dairy sires at Jiangxi Provincial Fine Breeding Farm were analysed with TTI method. TTI method evaluates dairy sires which include not only milk yields and fat percentages, but also total scores. The results indicate that TTI method has practical significance, and may be extended in dairy improvement.