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首页> 外文期刊>Tropical Animal Health and Production >Analysis of longitudinal data of beef cattle raised on pasture from northern Brazil using nonlinear models
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Analysis of longitudinal data of beef cattle raised on pasture from northern Brazil using nonlinear models

机译：使用非线性模型分析巴西北部牧场上饲养的肉牛的纵向数据

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This study was undertaken to aim of estimating the genetic parameters and trends for asymptotic weight (A) and maturity rate (k) of Nellore cattle from northern Brazil. The data set was made available by the Brazilian Association of Zebu Breeders and collected between the years of 1997 and 2007. The Von Bertalanffy, Brody, Gompertz, and logistic nonlinear models were fitted by the Gauss-Newton method to weight-age data of 45,895 animals collected quarterly of the birth to 750 days old. The curve parameters were analyzed using the procedures GLM and CORR. The estimation of (co)variance components and genetic parameters was obtained using the MTDFREML software. The estimated heritability coefficients were 0.21+or-0.013 and 0.25+or-0.014 for asymptotic weight and maturity rate, respectively. This indicates that selection for any trait shall results in genetic progress in the herd. The genetic correlation between A and k was negative (-0.57+or-0.03) and indicated that animals selected for high maturity rate shall result in low asymptotic weight. The Von Bertalanffy function is adequate to establish the mean growth patterns and to predict the adult weight of Nellore cattle. This model is more accurate in predicting the birth weight of these animals and has better overall fit. The prediction of adult weight using nonlinear functions can be accurate when growth curve parameters and their (co)variance components are estimated jointly. The model used in this study can be applied to the prediction of mature weight in herds where a portion of the animals are culled before they reach the adult age.Digital Object Identifier http://dx.doi.org/10.1007/s11250-012-0161-x
机译：进行这项研究的目的是估算来自巴西北部的内洛尔牛的遗传参数和渐进体重（A）和成熟率（k）的趋势。该数据集由巴西封牛育种协会提供，并于1997年至2007年之间收集。通过高斯-牛顿法将冯·贝塔朗菲，布罗迪，贡珀兹和逻辑Logistic非线性模型拟合到45,895的体重年龄数据每出生一个动物收集一次，直到750天大。使用GLM和CORR程序分析曲线参数。使用MTDFREML软件获得（协）方差成分和遗传参数的估计。渐近权重和成熟度的估计遗传力系数分别为0.21+或-0.013和0.25+或-0.014。这表明选择任何性状都将导致畜群的遗传进程。 A和k之间的遗传相关性为负（-0.57+或-0.03），表明选择高成熟度的动物应导致较低的渐近体重。冯·贝塔兰菲函数足以建立平均生长模式并预测内洛尔牛的成年体重。该模型可以更准确地预测这些动物的出生体重，并且具有更好的整体拟合度。当共同估计生长曲线参数及其（协）方差分量时，使用非线性函数预测成人体重可能是准确的。本研究中使用的模型可以用于预测成年畜群中成熟体重的预测，其中一部分动物在成年之前就被淘汰了。数字对象标识符http://dx.doi.org/10.1007/s11250-012 -0161-x

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