利用辅助性状提高半同胞测验的准确度

Increasing the Accuracy of the Half-sib Test with Auxiliary Traits

利用公畜半同胞个体包括主性状在内的若干个相关性状的表型值构造一个公畜指数，并导出利用该指数对公畜主性状进行选择的准确度．证明采用辅助性状时，半同胞测验的准确度总是高于未采用辅助性状时的准确度．数值计算结果表明，当各辅助性状和主性状的表型和遗传相关符号相反时，辅助性状的使用对选择准确度的提高最为显著．当辅助性状只有一个时，还导出一个计算给定准确度下每一公畜所需度量的半同胞个体数的公式．最后在一些简化条件下讨论辅助性状数目对选择准确度提高的影响．

One or more auxiliary traits in conjunction with the main trait are used to increase the accuracy of the half-sib test.A generalised sire index is proposed and a general expression for the accuracy of selection based on such a half-sib test is derived.It is proved that the accuracy of the half-sib test with auxiliary traits is always increased. Detailed numerical investigation with one auxiliary trait reveals that the maximum gain in accuracy is found when the phenotypic and additive genetic correlations between the main and the auxiliary traits are of opposite signs.A formula to compute the number of half-sib required to attain a preassigned value of accuracy is constructed. The effect of the number of auxiliary traits on the gain in accuracy is also,studied under some simplified situations.