Ptak E, Horst H S, Schaeffer L R
Department of Genetics and Animal Breeding, Academy of Agriculture, Krakow, Poland.
J Dairy Sci. 1993 Dec;76(12):3792-8. doi: 10.3168/jds.S0022-0302(93)77723-1.
Production records of 835,789 Ontario Holsteins calving between 1958 and 1990 were used to determine the presence of an interaction of the age and month of calving of cows with the year of calving for production of milk and fat and fat percentage. An animal model was employed including the effects of herd-year-season of calving, interaction of age and month of calving with year of calving, animal additive genetic effects, and permanent environmental effects. Tests for interactions of age with year within months of calving were significant for production of milk and fat, but not for fat percentage. Tests for interactions of month with year within age groups were significant for only a few age groups in the second and third parties. The implication of these findings on genetic evaluation is that an interaction of age and month of calving with year of calving should be included in the animal model for genetic evaluations rather than preadjusting production for age and month of calving.
利用1958年至1990年间安大略省835,789头荷斯坦奶牛的生产记录，来确定奶牛产犊年龄和月份与产犊年份之间的相互作用对产奶量、产脂量和乳脂率的影响。采用了一个动物模型，其中包括产犊畜群-年份-季节的影响、产犊年龄和月份与产犊年份的相互作用、动物加性遗传效应以及永久环境效应。在产犊月份内对年龄与年份相互作用的检验表明，产奶量和产脂量有显著影响，但对乳脂率没有显著影响。在年龄组内对月份与年份相互作用的检验仅在第二和第三年龄段的少数年龄组中有显著影响。这些发现对遗传评估的意义在于，在遗传评估的动物模型中应纳入产犊年龄和月份与产犊年份的相互作用，而不是对产犊年龄和月份进行产量预调整。
