Schaeffer L R, Jamrozik J
Department of Animal and Poultry Science, University of Guelph, ON, Canada.
J Dairy Sci. 1996 Nov;79(11):2044-55. doi: 10.3168/jds.S0022-0302(96)76578-5.
A multiple-trait procedure is described for predicting 305-d lactation yields for milk, fat, and protein that incorporates information about standard lactation curves and covariances between yields for milk, fat, and protein. Test day yields are weighted by their relative variances, and standard lactation curves of cows from similar breed, region, lactation number, age, and season of calving are used for the estimation of lactation curve parameters for each cow. Accuracies of the test interval method and the multiple-trait procedure were comparable. In addition, the multiple-trait procedure can handle long intervals between test days as well as test days with milk only recorded and can make 305-d predictions on the basis of just one test day record per cow. The procedure also lends itself to the calculation of peak yield, day of peak yield, yield persistency, and expected test-day yields, which could be useful management tools for a producer on a milk recording program.
本文描述了一种多性状方法，用于预测牛奶、脂肪和蛋白质的305天泌乳量，该方法纳入了关于标准泌乳曲线以及牛奶、脂肪和蛋白质产量之间协方差的信息。测定日产量根据其相对方差进行加权，并使用来自相似品种、地区、泌乳次数、年龄和产犊季节的奶牛的标准泌乳曲线来估计每头奶牛的泌乳曲线参数。测定间隔法和多性状方法的准确性相当。此外，多性状方法可以处理测定日之间的长间隔以及仅记录了牛奶的测定日，并且可以基于每头奶牛仅一条测定日记录做出305天的预测。该方法还适用于计算峰值产量、峰值产量日、产量持续性和预期测定日产量，这些对于参与牛奶记录计划的生产者而言可能是有用的管理工具。
