Abstract

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.

中文翻译：

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F1 罗曼诺夫杂交母羊与羊毛和毛品种在秋季产羔期间的性能、体重和寿命在六年生产期间的比较

摘要

本研究的目的是评估羊毛（多塞特和朗布依埃）和毛（杜泊、卡塔丁和白杜泊）品种在一年一度的秋季产羔系统中补充罗曼诺夫种质的能力，方法是估计直接的母系祖代和父系品种对经济的影响重要的羔羊和母羊特性。经过 3 年的春季产羔评估后，五种 F1 类型的母羊过渡到春季交配，暴露于复合终端公牛，并在 4、5 和 6 岁时在谷仓产羔系统下进行评估。从 5 月的 1,378 次暴露中，共有 527 头第一代杂交 (F1) 母羊生产了 1,151 窝和 2,248 只羔羊。考虑到母猪年龄、出生类型和性别的差异后，羔羊断奶存活率不受外祖代品种的影响（P= 0.30）。然而，出生于 50% 多塞特 (16.8 ± 0.21 kg) 或 50% 白杜泊母羊 (16.8 ± 0.28 kg) 的羔羊在断奶时比出生于 50% Katahdin 母羊的羔羊重 (13.8 ± 0.32 kg；P < 0.001)。此外，出生于 50% 多塞特母羊的羔羊比出生于 50% 朗布依埃 (16.0 ± 0.22 kg) 和 50% 杜珀母羊 (15.7 ± 0.33；P ≤ 0.03) 的羔羊重，但没有观察到其他成对的外祖代品种差异（P ≥0.06）。母羊体重 ( n= 3,629) 在六个可能的交配季节中的每一个之前记录，并且在各个年龄段中，多塞特和朗布依莱公羊母羊最大（分别为 56.7 ± 0.44 和 56.5 ± 0.45 公斤），杜泊和白杜泊公母的体重居中母羊（分别为 54.7 ± 0.78 和 54.1 ± 0.64 千克），对于卡塔丁种母羊（51.5 ± 0.45 千克）最少。生育弹簧配合（0.80±0.03至0.87±0.02），产仔数在出生时（1.46±0.09至1.71±0.07），和产仔在断奶（1.25±0.06到1.46±0.06）没有被公畜品种的影响（后P ≥ 0.16)。母羊寿命，评估为 6 年生产后出现的概率，也不受父系品种的影响（0.39 ± 0.03 至 0.47 ± 0.03；P= 0.44）。Rambouillet 公羊母羊断奶的羔羊总重（21.5 ± 0.94 kg）比 Katahdin 公羊母羊（17.8 ± 0.94 kg；P = 0.05），但未检测到其他公猪品种差异（P ≥ 0.07）。结果表明，将罗曼诺夫母羊纳入杂交系统是提高反季节母羊生产力的实用方法。