Ahlborn-Breier G, Hohenboken W D
Livestock Improvement Corporation, Ltd., New Zealand Dairy Board, Hamilton.
J Dairy Sci. 1991 Feb;74(2):592-602. doi: 10.3168/jds.S0022-0302(91)78206-4.
Coefficients for individual and maternal breed composition and the expected contributions of individual and maternal heterosis and breed source of cytoplasm were assigned to 42,554 primiparous Holstein-Friesian, Jersey, and crossbred cows. The individual additive genetic breed effect influenced all milk production traits. Highly significant maternal additive genetic breed effects equivalent to 3% of the mean were identified for milk yield and milk fat percentage. Individual heterosis was highly significant for milk yield and milk fat yield. A primiparous first cross cow produced 6.1% more milk and 7.2% more milk fat than the average of straightbred cows of both breeds. For milk fat yield, the individual heterosis effect was higher than the individual additive genetic breed difference between Jersey and Holstein-Friesian. A small negative maternal heterosis and a small effect of breed source of cytoplasm were estimated for milk fat percentage. Results suggest that individual heterosis is a major genetic effect for milk yield and milk fat yield. This heterosis could be utilized through a stratified breeding scheme in which high genetic merit nucleus herds maintain genetic progress in the two straightbred populations, and commercial dairy herds employ a rotational cross-breeding scheme to take advantage of both the additive genetic progress and nonadditive genetic effects.
个体和母体品种组成的系数，以及个体和母体杂种优势及细胞质品种来源的预期贡献，被分配给42,554头初产荷斯坦-弗里生牛、泽西牛和杂交母牛。个体加性遗传品种效应影响所有产奶性状。对于产奶量和乳脂率，确定了高度显著的母体加性遗传品种效应，相当于平均值的3%。个体杂种优势对产奶量和乳脂产量高度显著。一头初产一代杂交母牛比两个品种纯种母牛的平均值多产6.1%的牛奶和7.2%的乳脂。对于乳脂产量，个体杂种优势效应高于泽西牛和荷斯坦-弗里生牛之间的个体加性遗传品种差异。估计乳脂率存在小的负母体杂种优势和细胞质品种来源的小效应。结果表明，个体杂种优势是产奶量和乳脂产量的主要遗传效应。这种杂种优势可以通过分层育种方案来利用，其中高遗传价值的核心牛群保持两个纯种群体的遗传进展，而商业奶牛群采用轮回杂交育种方案来利用加性遗传进展和非加性遗传效应。
