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中国荷斯坦牛泌乳曲线数学模型拟合及应用

DOI: 10.7685/jnau.201501024

Keywords: 泌乳曲线, 校正系数, 非线性模型, 305 d产奶量
lactation curve
, adjustment factor, nonlinear model, 305 days milk yield

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Abstract:

[目的]本文旨在建立拟合中国荷斯坦牛泌乳曲线的数学模型,计算出一套可靠的305 d产奶量校正系数。[方法]分别使用Wood不完全伽玛模型、逆多项式模型、Ali-Schaeffer模型、六次多项式回归模型、Wilmink模型和Pollott模型对71个奶牛场43 812头中国荷斯坦牛的609 784条测定日记录进行了拟合。参数的估计使用SAS 9.2软件中的非线性回归过程迭代求解实现。[结果]6种数学模型的拟合度(R2值)为0.940~0.947。其中,六次多项式回归模型的拟合度(R2值)最大,模型估计误差标准差最小,在本次试验中拟合效果最好。[结论]用六次多项式回归模型计算出各泌乳时间的累积产奶量,继而提出了计算305 d产奶量的校正系数。结合实际累积产奶量和相应的校正系数能将所有未达到305 d产奶量的记录校正到305 d。
[Objectives]The aim of this study was to investigate the use of six different mathematical functions(Wood,Inverse polynomial,Ali-Schaeffer,Six polynomial,Wilmink and Pollott models)for describing the lactation curve of Chinese Holstein. [Methods]Dairy herd improvement(DHI)records were collected from 43 812 Holstein cows of 71 farms. In number of 609 784 test-day records were divided into first three parties. Nonlinear regression procedure was performed in SAS 9.2 software to compute the parameters of models. [Results]The goodness of fit(R2 values)of models ranged from 0.940 to 0.947. Polynomial model of degree 6 gave the best R2 values as well as the lowest mean square prediction error. Therefore we selected the Polynomial model of degree 6 to estimate the cumulative milk yield,and further obtained adjustment factors of lactation milk yield to 305 days for Chinese Holstein. [Conclusions]Using the actual cumulative milk yields and the adjustment factors,we can adjust records of milk yields that do not meet all the 305 days to 305 days

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