Rumph J M, Koch R M, Gregory K E, Cundiff L V, Van Vleck L D
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
J Anim Sci. 2002 Mar;80(3):583-90. doi: 10.2527/2002.803583x.
Genetic parameters of mature weight are needed for effective selection and genetic evaluation. Data for estimating these parameters were collected from 1963 to 1985 and consisted of 32,018 mature weight records of 4,175 Hereford cows that were in one control and three selection lines that had been selected for weaning weight, for yearling weight, or for an index combining yearling weight and muscle score for 22 yr. Several models and subsets of the data were considered. The mature weight records consisted of a maximum of three seasonal weights taken each year, at brand clipping (February and March), before breeding (May and June), and at palpation (August and September). Heritability estimates were high (0.49 to 0.86) for all models considered, which suggests that selection to change mature weight could be effective. The model that best fit the data included maternal genetic and maternal permanent environmental effects in addition to direct genetic and direct permanent environmental effects. Estimates of direct heritability with this model ranged from 0.53 to 0.79, estimates of maternal heritability ranged from 0.09 to 0.21, and estimates of the genetic correlation between direct and maternal effects ranged from -0.16 to -0.67 for subsets of the data based on time of year that mature weight was measured. For the same subsets, estimates of the proportions of variance due to direct permanent environment and maternal permanent environment ranged from 0.00 to 0.09 and 0.00 to 0.06, respectively. Using a similar model that combined all records and included an added fixed effect of season of measurement of mature weight, direct heritability, maternal heritability, genetic correlation between direct and maternal effects, proportion of variance due to direct permanent environmental effects, and proportion of variance due to maternal permanent environmental effects were estimated to be 0.69, 0.13, -0.65, 0.00, and 0.04, respectively. Mature weight is a highly heritable trait that could be included in selection programs and maternal effects should not be ignored when analyzing mature weight data.
有效的选择和遗传评估需要成熟体重的遗传参数。用于估计这些参数的数据收集于1963年至1985年，包括4175头赫里福德母牛的32018条成熟体重记录，这些母牛处于一个对照组和三个选择系中，这三个选择系已针对断奶体重、周岁体重或结合周岁体重和肌肉评分的指数进行了22年的选择。考虑了几种模型和数据子集。成熟体重记录包括每年最多三次季节性体重，分别在烙印剪毛时（2月和3月）、配种前（5月和6月）以及触诊时（8月和9月）。对于所有考虑的模型，遗传力估计值都很高（0.49至0.86），这表明选择改变成熟体重可能是有效的。最适合数据的模型除了直接遗传和直接永久环境效应外，还包括母体遗传和母体永久环境效应。对于基于测量成熟体重时间的数据子集，该模型的直接遗传力估计值范围为0.53至0.79，母体遗传力估计值范围为0.09至0.21，直接和母体效应之间的遗传相关性估计值范围为-0.16至-0.67。对于相同的子集，直接永久环境和母体永久环境引起的方差比例估计值分别为0.00至0.09和0.00至0.06。使用一个类似的模型，该模型结合了所有记录并包括成熟体重测量季节的附加固定效应，直接遗传力、母体遗传力、直接和母体效应之间的遗传相关性、直接永久环境效应引起的方差比例以及母体永久环境效应引起的方差比例估计分别为0.69、0.13、-0.65、0.00和0.04。成熟体重是一个高度可遗传的性状，可以纳入选择计划，并且在分析成熟体重数据时不应忽视母体效应。
