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首页> 外文期刊>Archivos Latinoamericanos de Produccion Animal >Comparison of models in genetic evaluation o. f growth traits for Brahman cattle in southeastern Mexico.
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Comparison of models in genetic evaluation o. f growth traits for Brahman cattle in southeastern Mexico.

机译：遗传评估模型的比较o。墨西哥东南部婆罗门牛的生长特性。

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Variance components and genetic parameters for birth weight, BW (n=2905), adjusted weaning weight to 205 days, WW205 (n=2264) and preweaning daily gain, ADG (n=2264) in four herds of Brahman cattle in southeastern Mexico were estimated. Six animal models were fitted for each trait, ranging from a simple model with the additive direct effect (ó2a) as the only random effect to the complete model with ó2a, additive maternal effect (ó2m), covariance between them (óam ) and maternal permanent environmental effect (ó2c). The six models included as a fixed effects contemporary group of birth (Herd-Year-Season), Sex and parity number. Likelihood ratio test, prove for all traits, ó2m and óam were important (P 2c (P>0.05). Ignoring maternal effects in the models tended to increase direct heritability and also, ignoring óam tended to increase error. Subtract ó2c not affect direct and maternal heritability. Spearman correlations of direct and also for maternal animal genetic values, between models with and without ó2c were 1, suggesting no differences in the ranking of animal. The genetic correlations between additive and maternal heritabilities for all characteristics were negative, affecting estimated total heritability (Lower than in models omitting óam). The additive genetic variance given maternal effects (ó2a.m) was constant across models suggesting a correct partition of additive genetic effects into their direct and maternal components. In conclusion, the most appropriate model must be selected for each characteristic, in order to reduce bias in genetic evaluation.
机译：墨西哥东南部四头婆罗门牛的出生体重BW（n = 2905），调整后的断奶体重至205天，WW205（n = 2264）和断奶前日增重ADG（n = 2264）的方差成分和遗传参数为估计。为每种性状拟合了六个动物模型，从简单的模型（具有加法直接效应（ó 2 a ）作为唯一的随机效应）到具有ó< sup> 2 a ，加性母体效应（ó 2 m ），它们之间的协方差（ó am ）和母亲的永久环境影响（ó 2 c ）。这六个模型包括作为固定效应的当代出生群体（年份-季节），性别和奇偶数。似然比检验证明所有特征ó 2 m 和ó am 都很重要（P 2 c < / sub>（P> 0.05）。忽略模型中的母体效应往往会增加直接遗传力，而忽略ó am 也会增加误差。减去ó 2 c 不会影响直接遗传和母体遗传。在有和没有ó 2 c 的模型之间，直接和母体动物遗传值的Spearman相关性分别为1，说明所有特征的加性和母体遗传力之间的遗传相关性为负，影响估计的总遗传力（低于省略了 am 的模型）。各模型之间的效应（ó 2 am ）是恒定的，表明加性遗传效应正确分配到其直接和母体成分中。必须为每个特征选择l，以减少遗传评估中的偏倚。

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