Rekik B, Berger P J
Department of Animal Science, Iowa State University, Ames 50011, USA.
J Dairy Sci. 1997 May;80(5):957-64. doi: 10.3168/jds.S0022-0302(97)76020-X.
The ability of animal model evaluations to predict the genetic potential of a bull from his sire and maternal grandsire was investigated. Theoretical coefficients were derived for different combinations of progeny records on the bull, sire, and maternal grandsire. Coefficients > 0.50 for sires and > 0.25 for maternal grandsires were associated with bulls with few daughters. Ten animal model evaluations of Holsteins, July 1989 to January 1994, were used to estimate coefficients realized in three populations: 1) all AI bulls (n = 6924), 2) current AI bulls (n = 1344), and 3) elite AI bulls (n = 6116). The PTA were analyzed for milk, fat, and protein yields, and for fat and protein percentages. Birth year of sons nested within the birth year of their sire was included as a random effect with a first-order autoregressive process for the regression model used to estimate the realized coefficients for sires and maternal grandsires. After adjustment for the genetic trend for estimates of sires, the correlation coefficient between predicted merit of sons from 2 consecutive yr ranged from 0.34 to 0.87. The PTA of bulls from first-crop evaluation were accurately predicted from PTA of sire and maternal grandsire for yield and percentage traits.
研究了动物模型评估从公牛的父亲和外祖父预测其遗传潜力的能力。推导了公牛、父亲和外祖父后代记录不同组合的理论系数。父亲系数>0.50且外祖父系数>0.25与女儿数量少的公牛相关。使用1989年7月至1994年1月的十次荷斯坦奶牛动物模型评估来估计三个群体中实现的系数：1）所有人工授精公牛（n = 6924），2）当前人工授精公牛（n = 1344），3）精英人工授精公牛（n = 6116）。分析了产奶量、乳脂量、乳蛋白产量以及乳脂率和乳蛋白率的预测传递能力（PTA）。嵌套在其父系出生年份内的儿子出生年份作为随机效应纳入用于估计父亲和外祖父实现系数的回归模型的一阶自回归过程。在对父亲估计的遗传趋势进行调整后，连续两年儿子预测优点之间的相关系数范围为0.34至0.87。对于产量和百分比性状，首次评估公牛的PTA可从父亲和外祖父的PTA准确预测。
