This work aimed to evaluate the effects of sire's and dam's biological type, dam's age class at calving and individual heterozygosis, and to estimate variance components for weaning weight adjusted to 210 days (WW210) in beef cattle of different breed groups. Records of 13 687 animals, obtained from 2000 to 2007, were used. Bulls from the biological types Zebu (N), Adapted (A), British (B), Continental (C) and ¼N|¼A|¼B|¼C were mated with purebred zebu (N) and crossbred females (½C|½N and ½B|½N). Dam age at calving was 3–12 years. The influence of several effects on WW210 was tested using the least square method. Variance component analysis was performed using a Bayesian approach. The model included contemporary group, dam's age class at calving, sire's and dam's biological types as systematic effects, animal's age and individual heterozygosis as linear covariates, and direct and maternal additive genetic, maternal permanent environmental and residual effects as random effects. The progeny of bulls from biological type B and the crossbred cows showed higher WW210 means. Cows at 6–7 years old weaned heavier calves. Direct and maternal heritability estimates for WW210 were 0.5 ± 0.04 and 0.1 ± 0.02, respectively. Calves with 100% individual heterozygosis weighed on average 25.98 kg more at weaning compared to progenies from pure breeds. Sire's and dam's biological types influence the WW210 of the crossed progenies. Crossbred cows produce heavier calves compared to biological type N cows. These results and the obtained direct and maternal heritabilities suggest it is possible to choose the lines of sires and dams that could be used to make the crosses to obtain progenies with better performance for WW210.

中文翻译：

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遗传和环境对杂交肉牛（Bos taurus × Bos indicus）断奶体重的影响

这项工作旨在评估父系和母系的生物学类型、母系在产犊时的年龄等级和个体杂合性的影响，并估计不同品种肉牛调整为 210 天 (WW210) 的断奶体重的方差分量。使用了从 2000 年到 2007 年获得的 13 687 只动物的记录。来自生物类型瘤牛 (N)、适应 (A)、英国 (B)、大陆 (C) 和 ¼N|¼A|¼B|¼C 的公牛与纯种瘤牛 (N) 和杂交雌性 (½C|½N 和 ½B|) 交配½N)。产犊时的大坝年龄为 3-12 年。使用最小二乘法测试了几种效应对 WW210 的影响。使用贝叶斯方法进行方差分量分析。该模型包括当代群体、母牛在产犊时的年龄等级、父亲和母马的生物学类型作为系统效应、动物' s 年龄和个体杂合性作为线性协变量，直接和母体加性遗传、母体永久环境和残留效应作为随机效应。来自生物型 B 的公牛和杂交奶牛的后代表现出更高的 WW210 平均值。6-7 岁的奶牛断奶较重的小牛。WW210 的直接和母体遗传力估计值分别为 0.5 ± 0.04 和 0.1 ± 0.02。与纯种后代相比，具有 100% 个体杂合子的小牛在断奶时平均重 25.98 公斤。父亲和母亲的生物学类型影响杂交后代的 WW210。与生物 N 型奶牛相比，杂交奶牛产生的小牛更重。