USDA, ARS, U.S. Sheep Experiment Station, Dubois, ID 83423, USA.
J Anim Sci. 2012 Sep;90(9):2931-40. doi: 10.2527/jas.2011-4640. Epub 2012 Jun 4.
A 3-yr study was conducted to comprehensively evaluate Columbia, Suffolk, USMARC-Composite (Composite), and Texel breeds as terminal sires in an extensive rangeland production system. The objective was to estimate breed-of-ram effects on ewe fertility, prolificacy, and dystocia, and sire breed effects on lamb survival and growth until weaning at approximately 132 d of age. Data were from 22 Columbia, 22 Composite, 21 Suffolk, and 17 Texel rams with 957 exposures to 574 adult Rambouillet ewes (3- to 7-yr-old at lambing), 908 lambings, and 1,834 lambs. Ram breed did not affect ewe fertility (mean = 94.9%; p = 0.73), total number born per ewe lambing (mean = 2.02 lambs; p = 0.20), number born alive per ewe lambing (mean = 1.90 lambs; p = 0.24), or number weaned per ewe lambing (mean = 1.45 lambs, p = 0.94). Dystocia rates were different (p = 0.01) for ewes mated to Columbia (12.2%), Composite (13.5%), Suffolk (25.7%), and Texel rams (31.9%) during 1 yr of the study, but differences among ram breeds were not repeatable (p ≥ 0.38) during the other 2 yr. Suffolk-sired lambs were heavier (p ≥ 0.02) at birth (5.5 kg) and weaning (40.3 kg) than lambs sired by the other breeds, which did not differ (p ≥ 0.34) for birth weight (mean = 5.3 kg). Texel-sired lambs (37.4 kg) were lighter (p ≥ 0.02) at weaning than Columbia- (38.8 kg) and Composite-sired (38.4 kg) lambs, which did not differ (p = 0.40) for weaning weight. Sire breed effect approached significance (p = 0.06) for lamb survival to weaning; estimated survival probabilities were 0.87 (Columbia), 0.89 (Composite), 0.93 (Suffolk), and 0.86 (Texel) for lambs reared by their birth dam. Interaction between sire breeds and birth weight affected (p < 0.001) lamb survival and revealed that lightweight Columbia- and Suffolk-sired lambs had a greater risk of death than lightweight lambs sired by Composite and Texel rams, but risk of death did not increase substantially for heavyweight lambs from any of the breeds. When mated to adult Rambouillet ewes in an extensive rangeland production system, the use of Suffolk rams is warranted to improve preweaning growth of market lambs and is not predicted to affect ewe fertility, ewe prolificacy, dystocia, or lamb survival compared with the other sire breeds we tested.
一项为期 3 年的研究旨在全面评估哥伦比亚、萨福克、美国马里兰综合（综合）和特克塞尔品种作为广泛的牧场生产系统中的终端种公羊。目的是估计公羊品种对母羊繁殖力、多产性和难产的影响，以及公羊品种对羔羊在断奶前约 132 天的生存和生长的影响。数据来自 22 只哥伦比亚公羊、22 只综合公羊、21 只萨福克公羊和 17 只特克塞尔公羊，共对 574 只成年雷马绵羊（产羔时 3-7 岁）、908 次配种和 1834 只羔羊进行了 957 次配种。公羊品种对母羊繁殖力（平均=94.9%；p=0.73）、每只母羊产仔数（平均=2.02 只羔羊；p=0.20）、每只母羊产活仔数（平均=1.90 只羔羊；p=0.24）或每只母羊断奶数（平均=1.45 只羔羊，p=0.94）没有影响。在研究的 1 年内，配种给哥伦比亚（12.2%）、综合（13.5%）、萨福克（25.7%）和特克塞尔公羊的母羊难产率不同（p=0.01），但在其他 2 年内，公羊品种之间的差异不具有重复性（p≥0.38）。萨福克公羊所产羔羊在出生（5.5 公斤）和断奶（40.3 公斤）时比其他品种的羔羊重（p≥0.02），而其他品种的羔羊在出生体重上没有差异（p≥0.34）（平均=5.3 公斤）。特克塞尔公羊所产羔羊（37.4 公斤）在断奶时比哥伦比亚（38.8 公斤）和综合公羊（38.4 公斤）所产羔羊轻（p≥0.02），而这两个品种在断奶体重上没有差异（p=0.40）。公羊品种对羔羊断奶前的成活率有一定的影响（p=0.06）；由其生母抚养的羔羊的估计成活率分别为 0.87（哥伦比亚）、0.89（综合）、0.93（萨福克）和 0.86（特克塞尔）。公羊品种与初生重的互作影响（p<0.001）了羔羊的成活率，表明轻体重的哥伦比亚和萨福克公羊所产羔羊的死亡风险高于轻体重的复合和特克塞尔公羊所产羔羊，但对于任何品种的重体重羔羊，死亡风险并没有显著增加。在广泛的牧场生产系统中与成年雷马绵羊配种时，使用萨福克公羊可以提高商品羔羊的断奶前生长速度，与我们测试的其他种公羊相比，预计不会影响母羊的繁殖力、多产性、难产或羔羊的成活率。
