Martinez M L, Lee A J, Lin C Y
Centro Nacional de Pesquisa de Gado de Leite, Coronel Pacheco, M. G., Brazil.
J Dairy Sci. 1988 Mar;71(3):800-8. doi: 10.3168/jds.S0022-0302(88)79620-4.
Data of 6482 lactations from 14 crossbred (Holstein x Zebu) herds in Brazil were used to study breed additive and heterosis effects for first, second, third, and first to fifth lactation milk yields, age at first calving, calving interval, and milk yield divided by calving interval, as well as the effect of age at calving on milk yield. Holstein additive expressed as deviation from Zebu and heterosis effects were highly significant for all traits. For each percentage of Holstein gene contribution an increase of 10.02, 12.02, 12.51, and 12.15 kg of milk were expected for first, second, third, and first to fifth lactation yields, respectively. Corresponding heterosis effects on those traits were 3.80, 3.39, 4.02, and 3.90 kg of milk for each percentage of heterozygosity. Replacement of pure Zebu genes by Holstein genes reduced age at first calving by 6 mo and shortened calving interval by 37 d. Holstein x Zebu heterotic effect decreased age at first calving by 2 mo and calving interval by 39 d. Holstein additive and heterosis effects for milk yield divided by calving interval were 3.4 and 1.3 kg of milk/d, respectively. Fitting breed additive and heterozygosity effects accounted for 99% of the genetic effects except for first to fifth lactation milk yield.
利用巴西14个杂交（荷斯坦×泽布牛）牛群的6482次泌乳数据，研究了第一、第二、第三以及第一至第五泌乳期的产奶量、初产年龄、产犊间隔、产奶量除以产犊间隔的品种加性效应和杂种优势效应，以及产犊年龄对产奶量的影响。以偏离泽布牛表示的荷斯坦牛加性效应和杂种优势效应在所有性状上均高度显著。对于每一个荷斯坦基因贡献率百分点，预计第一、第二、第三以及第一至第五泌乳期的产奶量分别增加10.02、12.02、12.51和12.15千克。对于这些性状，每一个杂合度百分点对应的杂种优势效应分别为3.80、3.39、4.02和3.90千克牛奶。用荷斯坦基因替代纯泽布牛基因可使初产年龄降低6个月，产犊间隔缩短37天。荷斯坦×泽布牛的杂种优势效应使初产年龄降低2个月，产犊间隔缩短39天。产奶量除以产犊间隔的荷斯坦牛加性效应和杂种优势效应分别为3.4和1.3千克牛奶/天。除第一至第五泌乳期产奶量外，拟合品种加性效应和杂合度效应占遗传效应的99%。
