Murphy Thomas W, Freking Brad A
U.S. Meat Animal Research Center, USDA, ARS, Clay Center, NE, USA.
J Anim Sci. 2021 Jan 1;99(1). doi: 10.1093/jas/skaa400.
The objective of this study was to evaluate wool (Dorset and Rambouillet) and hair (Dorper, Katahdin, and White Dorper) breeds for their ability to complement Romanov germplasm in an annual fall lambing system by estimating direct maternal grandsire and sire breed effects on economically important lamb and ewe traits. After 3 yr of evaluation under spring lambing, ewes of the five F1 types were transitioned to spring mating, exposed to composite terminal sires, and evaluated under a barn lambing system at 4, 5, and 6 yr of age. A total of 527 first generation crossbred (F1) ewes produced 1,151 litters and 2,248 lambs from 1,378 May exposures. After accounting for differences in dam age, birth type, and sex, lamb survival to weaning was unaffected by maternal grandsire breed (P = 0.30). However, lambs born to 50% Dorset (16.8 ± 0.21 kg) or 50% White Dorper ewes (16.8 ± 0.28 kg) were heavier at weaning than those born to 50% Katahdin dams (13.8 ± 0.32 kg; P < 0.001). Additionally, lambs born to 50% Dorset ewes were heavier than those born to 50% Rambouillet (16.0 ± 0.22 kg) and 50% Dorper ewes (15.7 ± 0.33; P ≤ 0.03), but no other pairwise maternal grandsire breed differences were observed (P ≥ 0.06). Ewe body weight (n = 3,629) was recorded prior to each of six possible mating seasons and, across ages, was greatest for Dorset- and Rambouillet-sired ewes (56.7 ± 0.44 and 56.5 ± 0.45 kg, respectively), intermediate for Dorper- and White Dorper-sired ewes (54.7 ± 0.78 and 54.1 ± 0.64 kg, respectively), and least for Katahdin-sired ewes (51.5 ± 0.45 kg). Fertility after spring mating (0.80 ± 0.03 to 0.87 ± 0.02), litter size at birth (1.46 ± 0.09 to 1.71 ± 0.07), and litter size at weaning (1.25 ± 0.06 to 1.46 ± 0.06) were not impacted by sire breed (P ≥ 0.16). Ewe longevity, assessed as the probability of being present after 6 production years, was also not affected by sire breed (0.39 ± 0.03 to 0.47 ± 0.03; P = 0.44). Rambouillet-sired ewes weaned more total weight of lamb (21.5 ± 0.94 kg) than Katahdin-sired ewes (17.8 ± 0.94 kg; P = 0.05), but no other sire breed differences were detected (P ≥ 0.07). Results demonstrated that incorporating the Romanov into a crossbreeding system is a practical means of improving out-of-season ewe productivity.
本研究的目的是通过估计直接母系祖父和父系品种对经济上重要的羔羊和母羊性状的影响，评估羊毛品种（多塞特和兰布耶）和毛发品种（杜泊、卡他丁和白杜泊）在年度秋季产羔系统中补充罗曼诺夫种质的能力。在春季产羔条件下评估3年后，将5种F1类型的母羊转为春季配种，与复合终端公羊交配，并在4、5和6岁时在棚内产羔系统下进行评估。共有527只第一代杂交（F1）母羊在1378次5月配种中产下1151窝2248只羔羊。在考虑母羊年龄、出生类型和性别的差异后，羔羊断奶成活率不受母系祖父品种的影响（P = 0.30）。然而，50%多塞特母羊所生的羔羊（16.8±0.21千克）或50%白杜泊母羊所生的羔羊（16.8±0.28千克）在断奶时比50%卡他丁母羊所生的羔羊（13.8±0.32千克）更重（P < 0.001）。此外，50%多塞特母羊所生的羔羊比50%兰布耶母羊（16.0±0.22千克）和50%杜泊母羊所生的羔羊（15.7±0.33千克）更重（P≤0.03），但未观察到其他成对母系祖父品种差异（P≥0.06）。在六个可能的配种季节之前记录母羊体重（n = 3629），在不同年龄阶段中，多塞特和兰布耶父系的母羊体重最大（分别为56.7±0.4和56.5±0.45千克），杜泊和白杜泊父系的母羊体重居中（分别为54.7±0.78和54.1±0.64千克），卡他丁父系的母羊体重最小（51.5±0.45千克）。春季配种后的受胎率（0.80±0.03至0.87±0.02）、出生时的窝产仔数（1.46±0.09至1.71±0.07）和断奶时的窝产仔数（1.25±0.06至1.46±0.06）不受父系品种的影响（P≥0.16）。母羊的长寿，即6个生产年后仍存活的概率，也不受父系品种的影响（0.39±0.03至0.47±0.03；P = 0.44）。兰布耶父系的母羊断奶时的羔羊总重量（21.5±0.94千克）比卡他丁父系的母羊（17.8±0.94千克）更多（P = 0.05），但未检测到其他父系品种差异（P≥0.07）。结果表明，将罗曼诺夫品种纳入杂交系统是提高非季节性母羊生产力的一种实用方法。
