OPTIMUM TRUNCATION POINTS FOR INDEPENDENT CULLING LEVEL SELECTION ON A MULTIVARIATE NORMAL-DISTRIBUTION, WITH AN APPLICATION TO DAIRY-CATTLE SELECTION
OPTIMUM TRUNCATION POINTS FOR INDEPENDENT CULLING LEVEL SELECTION ON A MULTIVARIATE NORMAL-DISTRIBUTION, WITH AN APPLICATION TO DAIRY-CATTLE SELECTION
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DOI：
10.1051/gse:19890207
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发表时间：
1989-01-01
影响因子：
4.1
通讯作者：
COLLEAU, JJ
中科院分区：
文献类型：
--
作者：
DUCROCQ, V;COLLEAU, JJ
在育种项目中，独立的筛选水平选择经常被采用，因为某些特殊性状的极端动物被育种者拒绝，或者因为遗传评估所依据的记录是按顺序收集的。为给定的总体育种目标优化这些选择程序相当于找到截断阈值或淘汰水平的组合，使所选动物的总体遗传值的期望值最大化。对于任意数量的正态分布性状和被选中的总概率是固定的，我们推导出了一种通用的牛顿型算法来实现这种最大化。利用一种强大的多元正态概率积分计算方法，可以同时考虑多达6个相关性状或选择阶段时，进行最优截断点的数值计算。将该算法扩展到更复杂的情况，即在非线性约束下最大化年度遗传响应，并使用涉及产奶量和次要性状（如类型）的奶牛模型进行了演示。考虑到四种选择途径中的三种：公牛的水坝；还有成群的奶牛。
Independent culling level selection is often practiced in breeding programs because extreme animals for some particular traits are rejected by breeders or because records on which genetic evaluation is based are collected sequentially. Optimizing these selection procedures for a given overall breeding objective is equivalent to finding the combination of truncation thresholds or culling levels which maximizes the expected value of the overall genetic value for selected animals. A general Newton-type algorithm has been derived to perform this maximization for any number of normally distributed traits and when the overall probability of being selected is fixed. Using a powerful method for the computation of multivariate normal probability integrals, it has been possible to undertake the numerical calculation of the optimal truncation points when up to 6 correlated traits or stages of selection are considered simultaneously. The extension of this algorithm to the more complex situation of maximizing annual genetic response subject to nonlinear constraints is demonstrated using a dairy cattle model involving milk production and a secondary trait such as type. Consideration is given to three of the four pathways of selection: dams of bulls; and sires of cows.