Hermas S A, Young C W, Rust J W
J Dairy Sci. 1987 Mar;70(3):712-5. doi: 10.3168/jds.S0022-0302(87)80062-0.
Production and reproduction records that spanned a 24-yr period were used to study the effects of low coefficients of inbreeding in two experiment station Guernsey herds. Inbreeding ranged from 0 to 25.3% and averaged 4.1%. Milk and fat yields were all first lactations standardized to a mature equivalent, twice daily milking, and 305 d. Intrasire regressions of production traits on percent inbreeding were -23.8 kg of milk, -1.25 kg of fat, and .002% for fat percentage. Estimates of the effect of inbreeding on reproductive traits had large standard errors but suggested that inbreeding depressed reproductive performance. Age at first calving decreased 3.7 d per 1% increase in inbreeding.
利用跨越24年的生产和繁殖记录，研究了两个实验站根西牛群中低近亲繁殖系数的影响。近亲繁殖率从0到25.3%不等，平均为4.1%。产奶量和脂肪产量均为首次产奶量，按成熟当量、每日两次挤奶和305天进行标准化。生产性状对近亲繁殖百分比的父系内回归为：产奶量-23.8千克、脂肪-1.25千克、脂肪百分比0.002%。近亲繁殖对繁殖性状影响的估计标准误差较大，但表明近亲繁殖会降低繁殖性能。近亲繁殖每增加1%，首次产犊年龄就会减少3.7天。
