Snowders G D, Duckett S L
USDA, ARS, U. S. Sheep Experiment Station, Dubois, ID 83423, USA.
J Anim Sci. 2003 Feb;81(2):368-75. doi: 10.2527/2003.812368x.
The South African Dorper is an important terminal meat sire breed in Africa that was recently imported into the United States. The objective of this study was to evaluate the Dorper as a terminal meat sire breed for U.S. production. Semen from purebred Dorper sires was used to artificially inseminate Columbia ewes to produce F1 crossbred lambs. Growth and carcass characteristics of F1 Dorper-Columbia lambs (n = 165), F1 Suffolk-Columbia (n = 89), and purebred Columbia lambs (n = 207) were compared based on subsets of the total number of animals. The F1 Dorper lambs grew significantly slower (313 g x d(-1)) and weighed less (29.8 kg) than F1 Suffolk- (357 g x d(-1), 33.5 kg) and Columbia-sired lambs (328 g x d(-1), 31 kg) at 77 d of age. However, at a weaning age of 118 d weaning weight and ADG did not differ (P > 0.20) among sire breed groups. Postweaning growth of F1 Dorper(239 g xd(-1)) wether lambs did not differ from that of purebred Columbia wethers (230 g x d(-1)) but was less than that of F1 Suffolk lambs (259 g x d(-1); P= 0.09). Feed efficiency did not differ among breed types. Breed types had similar dressing percentages (53%), shoulder fat depth (2.8 mm), body wall thickness (3 cm), leg conformation score (Choice), Yield grade (2.4), and Quality grade (Choice). Weight of wholesale shoulders and racks made up approximately 38% of the carcass weight in the Columbia and F1 Suffolk-Columbia type but only 33% in the F1 Dorper-Columbia lambs. However, the more expensive wholesale loins from F1 Dorpers were heavier (P < 0.01) than the other breed types. Total weights of wholesale legs were similar among F1 Dorpers and F1 Suffolks but were heavier than those for the purebred Columbia (P < 0.05). Percentages of total wholesale primal cuts were similar among breed types (P > 0.10). Chemical composition of the carcass did not differ significantly between breed types with a mean composition of 52% moisture, 30% lipid (ether extract), 17% protein, and 0.76% ash. Warner-Bratzler shear force values were less (P < 0.05) and sensory panel ratings for tenderness were significantly more favorable for lamb chops from Dorper sired lambs. Dorper rams can be used as terminal meat sires to produce lambs whose growth rate to 118 d of weaning age, postweaning ADG and feed efficiency, and carcass characteristics are similar to that of Suffolk crossbred lambs and purebred Columbia lambs but with a slight improvement in tenderness.
南非杜泊羊是非洲一种重要的终端肉用父本品种，最近被引入美国。本研究的目的是评估杜泊羊作为美国生产用终端肉用父本品种的性能。使用纯种杜泊羊公羊的精液对哥伦比亚母羊进行人工授精，以生产F1代杂交羔羊。基于动物总数的子集，比较了F1代杜泊-哥伦比亚羔羊（n = 165）、F1代萨福克-哥伦比亚羔羊（n = 89）和纯种哥伦比亚羔羊（n = 207）的生长和胴体特征。F1代杜泊羔羊在77日龄时生长速度显著较慢（313 g·d⁻¹），体重比F1代萨福克羔羊（357 g·d⁻¹，33.5 kg）和哥伦比亚父本的羔羊（328 g·d⁻¹，31 kg）轻（29.8 kg）。然而，在118日龄断奶时，断奶体重和平均日增重在父本品种组之间没有差异（P > 0.20）。F1代杜泊阉公羊断奶后的生长速度（239 g·d⁻¹）与纯种哥伦比亚阉公羊（230 g·d⁻¹）没有差异，但低于F1代萨福克羔羊（259 g·d⁻¹；P = 0.09）。饲料效率在各品种类型之间没有差异。各品种类型的屠宰率（53%）、肩部脂肪厚度（2.8 mm）、体壁厚度（3 cm）、腿部形态评分（精选级）、产量等级（2.4）和质量等级（精选级）相似。哥伦比亚和F1代萨福克-哥伦比亚类型的整肩和整肋排重量约占胴体重量的38%，而在F1代杜泊-哥伦比亚羔羊中仅占33%。然而，F1代杜泊羊价格较高的整腰肉比其他品种类型更重（P < 0.01）。F1代杜泊羊和F1代萨福克羊的整腿总重量相似，但比纯种哥伦比亚羊的重（P < 0.05）。各品种类型的整胴体主要切块的百分比相似（P > 0.10）。各品种类型胴体的化学成分没有显著差异，平均组成为水分52%、脂质（乙醚提取物）30%、蛋白质17%和灰分0.76%。Warner-Bratzler剪切力值较低（P < 0.05），杜泊父本羔羊的羊排嫩度感官评分明显更高。杜泊公羊可作为终端肉用父本，生产出到118日龄断奶时的生长速度、断奶后平均日增重和饲料效率以及胴体特征与萨福克杂交羔羊和纯种哥伦比亚羔羊相似，但嫩度略有改善的羔羊。
