Fogarty N M, Dickerson G E, Young L D
J Anim Sci. 1984 Feb;58(2):301-11. doi: 10.2527/jas1984.582301x.
Ewe performance was compared for five pure breeds of sheep (Finnsheep, F; Rambouillet, R; Dorset, D; Targhee, T; Suffolk, S) and the crosses in development of two maternal composite lines (C1 = 1/2F1/4R1/4D and C2 = 1/2F1/4T1/4S). The data involved 10,959 breeding season records of 4,219 ewes by 412 sires. Ewe production and the components (fertility, litter size, neonatal and preweaning lamb survival and mean lamb weaning weight) were adjusted for age and standardized across season of lambing and years. The D and F ewes produced more weight of lamb/ewe exposed than R, S and T ewes because of higher D and F fertility, higher D lamb survival and larger F litters. First cross and inter se generations of C1 and C2 ewes averaged 17 to 27% higher fertility than the parental mean. Litter size averaged about one lamb higher for F than for other pure breeds, but only slightly higher for C1 and C2 than for the mean of F and other breeds. Lower neonatal survival for F than for other breeds and crosses was associated with the larger F litters and with 2 to 8% positive heterosis in the crosses. Preweaning survival of suckled and nursery lambs was low for F and S and positive heterosis ranged from 9 to 19% in crosses. Mean lamb weaning weights were highest for S, lowest for F, with little heterosis in crosses. Crossbred ewes reared .3 to .4 more lambs than mean for parental pure breeds. Heterosis in C1 and C2 ranged from 11 to 28% for lambs born, 27 to 43% for lambs weaned and 29 to 44% for weight of lamb weaned/ewe exposed. Decline in heterosis with inter se mating of crosses was no greater than expected from the reduction in predicted heterozygosity.
对五个纯种绵羊品种（芬兰羊，F；兰布列羊，R；多塞特羊，D；塔基羊，T；萨福克羊，S）以及两个母本合成系（C1 = 1/2F + 1/4R + 1/4D 和 C2 = 1/2F + 1/4T + 1/4S）培育过程中的杂交品种的母羊性能进行了比较。数据包括412头公羊与4219头母羊在繁殖季节的10959条记录。对母羊的生产性能及其组成部分（繁殖力、产羔数、新生羔羊和断奶前羔羊成活率以及平均羔羊断奶体重）进行了年龄校正，并在产羔季节和年份间进行了标准化。由于D和F品种的繁殖力更高、D品种的羔羊成活率更高以及F品种的产羔数更多，D和F品种的母羊每头参与繁殖的母羊所产羔羊的重量比R、S和T品种的母羊更高。C1和C2母羊的第一代杂交和互交后代的繁殖力比亲本均值平均高17%至27%。F品种的产羔数平均比其他纯种品种多约1只羔羊，但C1和C2品种仅比F品种和其他品种的均值略高。F品种的新生羔羊成活率低于其他品种和杂交品种，这与F品种较大的产羔数以及杂交品种中2%至8%的正向杂种优势有关。F和S品种的哺乳羔羊和保育羔羊的断奶前成活率较低，杂交品种的正向杂种优势在9%至19%之间。平均羔羊断奶体重以S品种最高，F品种最低，杂交品种中杂种优势较小。杂交母羊每头比亲本纯种品种的均值多饲养0.3至0.4只羔羊。C1和C2品种的杂种优势在出生羔羊方面为11%至28%，断奶羔羊方面为27%至43%，每头参与繁殖的母羊所产断奶羔羊的重量方面为29%至44%。杂交品种互交时杂种优势的下降不超过预期的预测杂合度降低幅度。
