Tess M W, MacNeil M D
Department of Animal and Range Sciences, Montana State University, Bozeman 59717.
J Anim Sci. 1994 Apr;72(4):851-6. doi: 10.2527/1994.724851x.
Mixed-model techniques were used to evaluate the importance of cytoplasmic genetic effects on growth traits in beef cattle. The data used were records on birth weight (BWT, n = 4,716), preweaning average daily gain (PREADG, n = 4,428), and postweaning average daily gain (POSTADG, n = 3,476) collected from 1935 through 1989 in a closed line of Hereford cattle (Miles City Line 1). Selection criterion was adjusted yearling weight. Cytoplasmic genetic effects were evaluated as both potential fixed and random genetic effects. Cytoplasmic sources (n = 26) were determined based on the foundation female in the maternal lineage of each animal. All foundation females were at least five generations removed from any descendant that produced a performance record. An animal model was used to account for all nuclear additive genetic variation among animals. Direct additive effects were estimated for all traits. Maternal additive and permanent environmental effects were estimated for BWT and PREADG. Fixed effects included year of birth, age of dam, sex of calf, and regressions on inbreeding of calf, inbreeding of dam, and age off postweaning gain test (POSTADG only). When cytoplasm was fit as a fixed effect, F-tests for cytoplasmic effects were not significant (P = .10 to .99) for any trait. Inclusion of cytoplasmic source (fixed) in the statistical model reduced residual standard deviations less than .1%. Variance components for cytoplasmic genetic effects were estimated simultaneously with variance components for direct, maternal, direct-maternal covariance, and maternal permanent environment using REML techniques. Cytoplasmic source accounted for .40, .00 and .00% of the phenotypic variance for BWT, PREADG, and POSTADG, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
采用混合模型技术评估细胞质遗传效应在肉牛生长性状中的重要性。所使用的数据是1935年至1989年期间在赫里福德牛封闭品系（迈尔斯城1系）中收集的出生体重（BWT，n = 4716）、断奶前平均日增重（PREADG，n = 4428）和断奶后平均日增重（POSTADG，n = 3476）记录。选择标准为调整后的周岁体重。细胞质遗传效应被评估为潜在的固定遗传效应和随机遗传效应。根据每头动物母系谱系中的基础母牛确定细胞质来源（n = 26）。所有基础母牛与产生性能记录的任何后代至少相隔五代。使用动物模型来解释动物之间所有的核加性遗传变异。估计了所有性状的直接加性效应。估计了BWT和PREADG的母体加性效应和永久环境效应。固定效应包括出生年份、母牛年龄、犊牛性别，以及犊牛近亲繁殖、母牛近亲繁殖和断奶后增重测试年龄（仅适用于POSTADG）的回归。当细胞质作为固定效应拟合时，对于任何性状，细胞质效应的F检验均不显著（P = 0.10至0.99）。在统计模型中纳入细胞质来源（固定）使残差标准差降低不到0.1%。使用REML技术同时估计细胞质遗传效应的方差分量以及直接、母体、直接-母体协方差和母体永久环境的方差分量。细胞质来源分别占BWT、PREADG和POSTADG表型方差的0.40%、0.00%和0.00%。（摘要截短为250字）
