Derivation and calculation of approximate reliabilities and daughter yield-deviations of a random regression test-day model for genetic evaluation of dairy cattle
Derivation and calculation of approximate reliabilities and daughter yield-deviations of a random regression test-day model for genetic evaluation of dairy cattle
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DOI：
10.3168/jds.s0022-0302(04)73348-2
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发表时间：
2004-06-01
影响因子：
3.5
通讯作者：
Reents, R
中科院分区：
文献类型：
--
作者：
Liu, Z;Reinhardt, F;Reents, R
试验日产奶量、脂肪、蛋白质产量和体细胞评分（SCS）分别采用前3次泌乳数据和随机回归模型进行分析。模型中使用的数据来自奥地利、德国和卢森堡以及荷尔斯坦、红牛和泽西牛。在一般的多性状模型（包括随机回归测试日模型）下，通过扩展单性状子代当量的概念，建立了多性状有效子代贡献（MTEDC）的可靠性近似方法。MTEDC适用于非常大的奶牛种群，大约有1550万头奶牛。与相应的迭代程序相比，可靠性计算所需的计算机内存更少，计算时间也大大缩短，相当于24轮迭代。在多性状模型下，推导了公牛产量偏差的计算公式。用MTEDC方法近似估计与儿媳妇产率偏差相关的信度。采用随机回归试验日模型对产儿率偏差公式和相关信度方法进行了仿真研究。所有公牛的泌乳产儿量偏差与常规遗传评估计算的育种估计值的相关系数为0.996，而只有短泌乳雌性的公牛的相关系数为0.95。
Test-day milk, fat, protein yield, and somatic cell score (SCS) were analyzed separately using data from the first 3 lactations and a random regression model. Data used in the model were from Austria, Germany, and Luxembourg and from Holstein, Red, and Jersey dairy cattle. For reliability approximation, a multiple-trait effective daughter contribution (MTEDC) method was developed under general multiple trait models, including random regression test-day models, by extending the single-trait daughter equivalents concept. The MTEDC was applied to the very large dairy population, with about 15.5 million animals. The calculation of reliabilities required less computer memory than the corresponding iteration program and a significantly lower computing time equivalent to 24 rounds of iteration. A formula for daughter-yield deviations was derived for bulls under multiple-trait models. Reliability associated with daughter-yield deviations was approximated using the MTEDC method. Both the daughter-yield deviation formula and associated reliability method were verified in a simulation study using the random regression test-day model. Correlations of lactation daughter-yield deviations with estimated breeding values calculated from a routine genetic evaluation were 0.996 for all bulls and 0.95 for young bulls having only daughters with short lactations.