Catillo G, Macciotta N P P, Carretta A, Cappio-Borlino A
Istituto Sperimentale per la Zootecnia, Roma, Italia.
J Dairy Sci. 2002 May;85(5):1298-306. doi: 10.3168/jds.S0022-0302(02)74194-5.
Test day (TD) records of milk production traits (milk yield, fat, and protein percentages) of 534 Italian buffalo cows were analyzed with a mixed linear model in order to estimate lactation curves pertaining to different ages at calving and different seasons of calving. Milk yield lactation curves of younger animals were lower than those of older animals until 20 wk from parturition. No effect of age at calving could be observed for fat and protein percentages. Season of calving affected milk yield only in the first phase of lactation, with the lowest production levels for summer calvings; no effect could be observed on fat and protein contents. Average correlations among TD measures within lactation were 0.59, 0.31, and 0.36 for milk yield, fat, and protein percentages, respectively. Five standard linear functions of time were able to reconstruct the average lactation curves. Goodness of fit was satisfactory for all models considered, although only the five-parameter model was flexible enough to fit all the three traits considered with excellent results.
对534头意大利水牛的产奶性状（产奶量、脂肪和蛋白质百分比）的测试日（TD）记录进行了混合线性模型分析，以估计与不同产犊年龄和不同产犊季节相关的泌乳曲线。直到分娩后20周，年轻动物的产奶量泌乳曲线低于年长动物。产犊时的年龄对脂肪和蛋白质百分比没有影响。产犊季节仅在泌乳的第一阶段影响产奶量，夏季产犊的产奶量最低；对脂肪和蛋白质含量没有影响。泌乳期内TD测量值之间的平均相关性分别为：产奶量0.59、脂肪0.31、蛋白质百分比0.36。五个标准时间线性函数能够重建平均泌乳曲线。尽管只有五参数模型足够灵活，可以很好地拟合所有三个考虑的性状，但所有考虑的模型的拟合优度都令人满意。
