Norman H D, Powell R L, Wright J R, Pearson R E
Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350, USA.
J Dairy Sci. 1996 Apr;79(4):689-701. doi: 10.3168/jds.S0022-0302(96)76415-9.
Milk records from Ayrshire, Brown Swiss, Guernsey, Jersey, and Milking Shorthorn cows that first calved between 18 and 35 mo were combined with scores for linear type traits collected before 43 mo during first lactation to study herd life and lifetime profitability. Profitability (discounted relative net income) was the value of milk, calves, and cow salvage minus fixed costs, operating costs, and cow depreciation costs. Cows were included if they appeared only in a single herd and if the herd remained on test for 72 mo after birth date of the cow. Phenotypic correlations were computed for milk and fat yields and for 14 type traits during first lactation with nine variables for lifetime performance from 3895 Ayrshire, 7997 Brown Swiss, 20,179 Guernsey, 71,731 Jersey, and 628 Milking Shorthorn cows. Multiple correlations for predicting discounted relative net income for the four breeds with the most data were 0.43 to 0.46 from milk and fat yields (linear and quadratic effects) during first lactation, 0.11 to 0.29 from final score, and 0.21 to 0.33 from all type traits. Type scores had considerably less predictive ability than yield during first lactation for predicting profitability and had limited predictability after yield was included. Final score increased multiple correlations only 0.00 to 0.02 above that for yield for the same four breeds. Final score plus 13 type traits (linear, quadratic, and interaction effects) increased multiple correlations only 0.02 to 0.04 above that for yield. Because of the limited value of some of the linear type traits, an effort should be initiated to eliminate them from programs of breed associations.
选取首次产犊时间在18至35月龄之间的爱尔夏牛、瑞士褐牛、格恩西牛、泽西牛和乳用短角牛的产奶记录，并结合首次泌乳期43月龄前收集的线性体型性状评分，以研究牛群寿命和终生盈利能力。盈利能力（贴现相对净收入）为牛奶、犊牛和母牛残值的价值减去固定成本、运营成本和母牛折旧成本。若母牛仅出现在一个牛群中，且该牛群在母牛出生日期后持续接受72个月的测试，则将其纳入研究。计算了3895头爱尔夏牛、7997头瑞士褐牛、20179体格恩西牛、71731头泽西牛和628头乳用短角牛在首次泌乳期的产奶量、产脂量与14个性状之间的表型相关性，以及与9个终生性能变量之间的表型相关性。对于数据量最多的四个品种，利用首次泌乳期的产奶量和产脂量（线性和二次效应）预测贴现相对净收入的复相关系数为0.43至0.46，利用最终评分预测的复相关系数为0.11至0.29，利用所有体型性状预测的复相关系数为0.21至0.33。在预测盈利能力方面，体型评分在首次泌乳期的预测能力远低于产奶量，且在纳入产奶量后预测能力有限。对于相同的四个品种，最终评分仅使复相关系数比产奶量的复相关系数提高了0.00至0.02。最终评分加上13个性状（线性、二次和交互效应）仅使复相关系数比产奶量的复相关系数提高了0.02至0.04。由于某些线性体型性状的价值有限，应着手从品种协会的计划中剔除它们。
