藏母羊妊娠后期补饲时间对其体况和羔羊初生重的影响分析

目的:探讨藏母羊妊娠后期补饲时间对其体况和羔羊初生重的影响因素.方法:选择该院2014年4月至2015年4月当地同期发情藏母羊180只研究对象,将其随机分成A组与B组(n=90).A组中的藏母羊分别于妊娠后期产羔前30d和35d开始饲补、B组中的藏母羊分别于妊娠后期产羔前45d和60d开始饲补,分析藏母羊妊娠后期补饲时间对其体况和羔羊初生的影响因素.结果:A组中的产前30d和35d补饲藏母羊,羔羊的体重明显低于B组中的45d和60d的体重,P<0.05,具有统计学意义.结论:羔羊初生的35d到60d补饲藏母羊对其体况和羔羊初生的体重影响不大,所以藏母羊妊娠后期的补饲最佳时间为35d到45d.     

母羊补饲不同饲料对哺乳羔羊生长发育的影响

为了探讨青海寒冷地区母羊不同补饲方式对哺乳羔羊生长发育的影响,试验选择产期接近、胎次为3～4胎、经同期发情处理的藏系母羊90只进行了羔羊生长性能和母羊体况测定。结果表明:对生产母羊进行补饲,尤其是在母羊妊娠后期及哺乳期补饲可以明显地增加羔羊的初生重、2月龄重、日增重、初生体尺和2月龄体尺,对母羊自身的体况恢复也有良好的效果。     

妊娠后期母羊饲粮精料比例对羔羊生长性能、消化性能及血清抗氧化指标的影响

本试验旨在研究妊娠后期母羊饲粮精料比例对羔羊生长性能、消化性能和血清抗氧化指标的影响。试验选用66只妊娠90 d、平均体重为(44.45±2.20)kg的初产湖羊,按照体重相近原则随机分为3组,每组11个重复,每个重复2只。各组母羊妊娠期饲粮精料比例分别为50%、40%和30%,分娩后母羊饲喂相同的全混合日粮(TM R)。羔羊10日龄,每只母羊取1只羔羊断母乳,饲喂代乳粉;15日龄补饲开食料;20日龄补饲苜蓿干草,自由采食至60日龄。每10 d测定1次羔羊体重,51~60日龄进行羔羊消化代谢试验,20和60日龄采集羔羊血液测定血清抗氧化指标。结果表明:妊娠后期母羊饲粮精料比例对羔羊1、10、20、30、40、50、60日龄体重,20、60日龄体尺指标及营养物质表观消化率均无显著影响(P0.05)。随母羊饲粮精料比例降低,20日龄羔羊血清总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活性极显著升高(P0.01),60日龄50%组显著或极显著低于其他2组(P0.05或P0.01);30%组20和60日龄羔羊血清谷胱甘肽过氧化物酶(GSH-Px)活性极显著高于其他2组(P0.01);血清中MDA的含量在20日龄时随母羊饲粮精料比例的降低而极显著降低(P0.01),60日龄时50%组显著高于30%组(P0.05)。结果提示,妊娠后期母羊饲粮的精料比例对产后早期断奶羔羊的体重、体尺、营养物质表观消化率无显著影响,但随母羊饲粮精料比例的降低,羔羊血清的抗氧化能力提高。     

哺乳期云上黑山羊羔羊生长规律及影响因素研究

为探索哺乳期云上黑山羊羔羊生长发育规律及其影响因素,本实验选取云上黑山羊初生羔羊60只,公、母各半,从出生开始直至90日龄断奶,每10 d进行1次体重测定,进行生长发育分析、趋势拟合和影响因素分析。结果表明:1～90日龄羔羊体重与日龄呈直线回归,公、母羔羊的回归直线差异极显著(P0.001);羔羊哺乳期日增重呈现波动变化,日增重类型通过聚类可分为0～10和70～90日龄为生长速度最快、60～70日龄生长速度次之、10～60日龄生长速度最慢3类;母羔的整个哺乳期生长与母羊产后体重、同窝羔羊数、窝重有显著相关(P0.05);除去20、60日龄体重外,母羔的其他哺乳期日龄体重与母羊年龄和胎次有显著相关(P0.05);公羔在整个哺乳期生长与母羊产后体重有显著相关,哺乳期早期生长与母羊年龄、胎次和窝重有显著相关(P0.05)。综上可知,云上黑山羊哺乳期羔羊体重与日龄呈直线回归,营养是影响羔羊生长的最主要因素,胎儿期的生长发育、母羊的母性行为对羔羊生长的影响取决于羔羊性别。     

冷季补饲对阿勒泰妊娠母羊及羔羊生长性能的影响

为了研究冷季补饲对阿勒泰妊娠母羊和羔羊生产性能的影响,2012年10月份—2013年8月份在阿勒泰市散德克库木种畜场选择年龄和胎次相同、体重接近的阿拉泰大尾母羊220只,随机分为对照组和试验组,试验组每只母羊每天补饲颗粒料600 g,对照组不补饲。试验羊分娩后测定母羊体重、羔羊初生重、初生体尺及每月体重、体尺指标。试验组母羊分娩的羔羊为试验组,断奶后补饲颗粒料;对照组母羊分娩的羔羊为对照组,不补饲颗粒饲料。结果表明:补饲颗粒料能显著增加母羊分娩体重,显著增加羔羊初生体高、体长和胸围(P0.05);羔羊断奶后补饲颗粒料可显著提高生产性能,120日龄时试验组羔羊体重极显著高于对照组羔羊(P0.01)。说明母羊和断奶羔羊补饲颗粒料可以提高羔羊体尺指标,促进前躯发育水平。     

放牧补饲精补料对妊娠后期和泌乳前期苏尼特母羊体重、血清生化指标和矿物质含量的影响

本试验旨在研究放牧补饲精补料对苏尼特母羊体重、血清生化指标和矿物质含量以及羔羊初生重的影响。试验采用单因子随机试验设计,选择体重、胎次接近、健康无病的苏尼特妊娠母羊66只,随机分为2组,每组33只。分娩前,对照组妊娠母羊补饲玉米和青干草,试验组则用等量的精补料代替对照组中的玉米;分娩后,对照组泌乳母羊补饲玉米、豆粕和青干草的混合料,试验组则用等量的精补料替代混合料中的玉米和豆粕。试验期120 d,分为妊娠后期与泌乳前期2个阶段。结果表明:试验组母羊补饲结束时体重以及羔羊初生重有高于对照组的趋势(0.05≤P≤0.10),羔羊2月龄体重显著高于对照组(P0.05),母羊产后2个月失重显著低于对照组(P0.05)。妊娠后期试验组血清碱性磷酸酶活性有高于对照组的趋势(0.05≤P≤0.10),血清磷、铜、锰、锌和硒含量显著高于对照组(P0.05)。泌乳前期试验组血清碱性磷酸酶活性以及尿素氮、钙、磷、镁、钾、铜、锌和铬含量显著高于对照组(P0.05),血清铁、钴和硒含量有高于对照组的趋势(0.05≤P≤0.10)。由此得出,放牧补饲精补料等量替代玉米或玉米与豆粕的混合料,促进了苏尼特母羊产后体重的恢复与羔羊的生长,提高了妊娠后期与泌乳前期母羊血清磷、镁、铜、锌、硒含量,以及泌乳前期母羊血清钙、钾、铁、钴和铬含量。     

妊娠后期放牧藏羊补饲试验

在青海省三角城种羊场对妊娠后期放牧藏羊进行了补饲试验,结果显示:补饲颗粒料组的藏羊繁殖成活率比对照组提高3.78%,羔羊死亡率比对照组减少2.37%,差异显著(P<0.05).平均毛长比对照组长6.01 cm,公羔和母羔出生重分别比对照组高0.56kg、0.44kg,羔羊细毛、两型毛和总毛量比对照组分别多328.3根、327.4根和628.8根.差异均极显著(P<0.01).说明放牧藏羊妊娠后期补饲颗粒料对母羊繁殖性能、羊毛生长、羔羊出生重有显著效果.补饲舔砖组的藏羊平均毛长比对照组长4.06cm,差异极显著(P<0.01),公、母羔出生体重分别比对照组高出0.06kg、0.3kg.母羔出生体重,差异显著(P<0.05).由于补饲舔砖组部分羊只出现腹泻对试验结果有一定影响.     

饲粮中添加铬对妊娠后期母羊繁殖性能及其子代羔羊生长发育的影响

本试验旨在研究饲粮中添加铬对妊娠后期母羊繁殖性能及其子代羔羊生长发育的影响。选用胎次(2胎)相同、体重[(52.36±8.24) kg]相近的处于妊娠(90±4) d的乐至黑山羊母羊40只,预饲7 d后,随机分为4组,每组10个重复,每个重复1只羊,单栏单饲。4组母羊分别饲喂在基础饲粮(铬含量为0.39 mg/kg DM)中添加0(对照)、0.4、1.2和2.0 mg/kg DM铬(铬源于丙酸铬)的试验饲粮。待母羊产仔后,调整羔羊数量使每只母羊所带羔羊数相等,进行母乳饲养至羔羊21日龄,试验期共81 d。结果显示:1)在妊娠后期母羊饲粮中添加不同水平的铬对妊娠后期和产后1～21 d母羊的干物质采食量(DMI)以及子代羔羊的生长性能均没有显著影响(P0.05)。2)在妊娠后期母羊饲粮中添加不同水平的铬对妊娠120 d母羊血清促黄体素(LH)和雌二醇(E2)含量没有显著影响(P0.05),但是可以线性提高妊娠120 d母羊血清孕酮(P4)含量(P=0.016 2),且血清促卵泡素(FSH)含量随铬添加水平的升高呈现先升高再降低的二次曲线变化趋势(P=0.050 4),在铬添加水平为0.4 mg/kg DM时有最大值。3)在妊娠后期母羊饲粮中添加不同水平的铬可以线性提高21日龄子代羔羊的肾脏指数(P=0.011 4)和瘤胃指数(P=0.024 8),且胸腺指数(P=0.014 0)随着铬添加水平的升高呈现先升高再降低的二次曲线变化,并在铬添加水平为1.2 mg/kg DM时有最大值。综合以上结果可知,在饲粮中添加铬可以在一定程度上提高妊娠后期母羊血清繁殖相关激素含量,并且可提高21日龄子代羔羊肾脏、胸腺和瘤胃指数。     

羔羊早期断奶的关键技术措施

推广运用羔羊早期断奶技术,可促使母羊提前结束泌乳,尽快进入再繁殖生产过程。从而提升肉羊生产水平,提高养羊效益。羔羊的早期断奶技术的实施需要掌握孕羊饲养管理、羔羊的护理、早期补饲、断奶方法、防疫保健等相关技术来支撑。1怀孕母羊的饲养管理要点1.1提供体质健壮、发育良好的羔羊,必须从羔羊胎儿期就开始培育,保证母羊妊娠后期营养是羔羊正常发育、增强羔羊体质的关键。母羊怀孕后期的2个月胎儿生长变快,妊娠母羊和胎儿共增重7～8千克,为满足母羊的生理需要,每天给怀孕期母羊补饲混合日粮0.5kg。1.2除补饲混合饲粮外,还应补饲优质青…     

萨福克羔羊0～65日龄生长发育规律研究

试验对萨福克羔羊0～65日龄生长发育规律进行了分析,旨在完善肉羊的生长发育规律研究,为萨福克羔羊0～65日龄的饲养管理及营养水平提供理论依据。试验于新疆华兴牧场惠康畜牧种羊繁育基地进行,供体母羊为纯种萨福克羊,受体母羊为哈萨克羊,并对出生的萨福克羔羊进行体尺、体重测量和记录,将数据输入Excel表格进行整理,并通过SPSS 16.0软件分析各性状平均值和各个体尺指标与体重平均值的相关性。结果表明,0～30日龄萨福克羊生长发育速度相对较快,公羔臀宽与体重的相关系数为0.989;管围与体重的相关系数为0.638;母羔臀宽与体重的相关系数为0.981,管围与体重的相关系数为0.654。0～30日龄萨福克羊公羔各性状的生长发育比母羔快,45～65日龄生长速度一致。羔羊0～15日龄体高、体长、胸围和体重等生长速度最快,而30～65日龄体高、体长、体重等部位生长速度较平稳;由体尺、体重相关性分析可知,臀宽与体重相关系数最大,管围和体重相关系数最小。由研究可知,0～30日龄营养要求关键,公羔与母羔的生长发育无明显差异,欲提高羔羊的生长发育速度则要注意羔羊各年龄阶段的生长发育规律,合理提供营养并提高饲料质量与管理水平。今后对萨福克羔羊的饲料管理中应该注重不同时期的饲养配方,合理改善饲养环境,使其发挥最大生长潜能。     

Effect of prenatal trenbolone acetate treatment on lamb performance and carcass characteristics

Forty-three pregnant Dorset and Dorset crossbred ewes were assigned randomly to a control group or implanted with either 300 mg trenbolone acetate (Low TBA) or 1,200 mg trenbolone acetate (High TBA) between d 40 and 60 of gestation. Adjusted weaning weights for ewe lambs were 23.3% less (P less than .10) with vs without TBA treatments. Postweaning ADG of ewe lambs was lower (P less than .05) but ADG of ram lambs was greater (P less than .05) for high TBA vs low TBA. Ewe lambs receiving high TBA had 19% less (P less than .05) gain per unit of feed than those receiving low TBA. Days on test for ewe lambs was greater (P less than .05) due to TBA treatment and for high TBA vs low TBA. Days on test for ram lambs was decreased (P less than .05) due to high TBA compared to low TBA. Subcutaneous fat over the ribeye and lower rib were greater (P less than .05) for high-TBA ewe lambs vs low-TBA ewe lambs. Percentage kidney and pelvic fat of ewe lambs was lower (P less than .05) due to TBA treatments. Ribeye area per unit of carcass weight was lower (P less than .05) in high-TBA ewe lambs vs low-TBA ewe lambs. Yield grade of ewe lambs was lower (P less than .05) for low TBA vs high TBA. Prenatal trenbolone acetate treatment of ewe lambs did not improve their subsequent postnatal growth performance and carcass traits. In addition, TBA implantation of the pregnant ewe produced dystocia and less milk production, as evidenced by the need for more lambs to be grafted.     

Genetic, environmental and interaction effects on lifetime production efficiency of crossbred ewes

A total of 399 crossbred ewes born in 2 yr were maintained either on irrigated or dryland hill pastures. The ewes were sired by North Country Cheviot, Dorset, Finnsheep or Romney rams mated to Suffolk or Columbia-type ewes. The crossbred ewes were mated to Hampshire rams throughout the study and had the opportunity for either 4 or 5 yr of production. Annual feed cost was calculated based upon estimated annual metabolizable energy (ME) requirements for maintenance, ewe growth, pregnancy and lactation. Income from weaned feeder lambs and from orphan lambs sold shortly after birth, feed cost and net revenue were analyzed during each ewe's first production year, as well as for the entire period of the experiment. Crossbred group significantly affected income from lambs produced, feed cost and net revenue for the ewes' first production year. Crossbred group and crossbred group X management system interactions generally influenced lifetime income from lambs produced and from orphans sold, gross income, total cost and net revenue per ewe. Finnsheep X Suffolk ewes performed best on irrigated pastures but were below average for lifetime net revenue on hill pastures. Finnsheep X Columbia ewes performed best on hill pastures and, with Dorset X Suffolk and Dorset X Columbia ewes, were well above average for lifetime net revenue on irrigated pastures as well. Suffolk crossbreds consistently performed better on irrigated than on hill pastures. While most ewes with Columbia-type inheritance were more efficient on hill than on irrigated pastures, this result was not always consistent.     

Comparison of performance of F1 Romanov crossbred ewes with wool and hair breeds during spring lambing under intensive and extensive production systems

The objective was to evaluate wool (Dorset and Rambouillet) and hair (Dorper, Katahdin, and White Dorper) breeds for their ability to complement Romanov germplasm in two distinct production systems by estimating direct sire and grandsire effects on lamb growth, survival, and ewe productivity traits. Rams of the five breeds (n = 75) were mated to Romanov ewes (n = 459) over a 3-yr period to produce five types of crossbred lambs (n = 2,739). Sire breed (P > 0.06) did not impact body weight or survival traits of the first-generation crossbred (F1) lambs. The productivity of retained crossbred ewes (n = 830) mated to Suffolk and Texel terminal sires was evaluated at 1, 2, and 3 yr of age in each production system. In the intensive production system, labor and harvested feed were provided for sheep that lambed in March in barns, and ewes were limited to rearing two lambs with additional lambs reared artificially. Ewes in the extensive production system lambed in May on pasture and were responsible for rearing all lambs born with no labor or supplemental feed provided before weaning. A total of 1,962 litters and 4,171 lambs from 2,229 exposures to two terminal sire breeds (Suffolk and Texel) were produced in the experiment. Crossbred ewes in the intensive production system were mated in October, resulting in larger litter sizes than crossbred ewes mated in December for the extensive production system. However, single- and twin-born lamb mortality was similar between the two systems that differed greatly in labor, feed, and facilities. Lambs produced in the intensive system received concentrate feed from an early age and were heavier at 24 wk of age than lambs produced in the extensive system. These outcomes resulted in greater 24-wk litter weight in the intensive than in the extensive system (P < 0.0001). Unexpectedly, the relative performance of crossbred types did not differ importantly between production systems. White Dorper × Romanov crossbred ewes had numerical advantages in productivity in each system; however, differences between ewe types were not significant. In the extensive system, without labor and shelter at lambing or supplemental feed until weaning, 3-yr-old crossbred ewes of all types averaged 1.78 lambs marketed per ewe lambing, and 40% of the ewes that gave birth to triplets weaned their entire litters. These results document that prolific sheep and extensive systems can be successfully combined if appropriate crossbred types are used.     

无角陶赛特羊和特克塞尔羊繁殖性能及生长性能的研究

该研究旨在初步了解无角陶赛特羊和特克塞尔羊对甘肃榆中地区的适应性,以便为该地区引进推广良种肉羊提供依据。以兰州奉特动物科技有限公司榆中肉羊繁育中心的无角陶赛特羊和特克塞尔羊为研究对象,对其2016—2018年的繁殖性能进行了分析,同时对2018年无角陶赛特羔羊和特克塞尔羔羊从出生到2月龄(断奶)的生长发育性能进行了测定。结果表明:从2016年到2018年无角陶赛特羊、特克塞尔羊的繁殖率、产羔率、双羔率均在逐年提高;特克塞尔羔羊初生重、1月龄重以及2月龄重均高于无角陶赛特羔羊,但差异均不显著(P>0.05);特克塞尔羔羊1月龄胸宽、2月龄胸宽和体长均显著高于无角陶赛特羔羊(P<0.05),其他体尺指标差异均不显著(P>0.05)。说明两个肉羊品种在甘肃榆中地区均有良好的繁殖性能以及较高的生长性能,均可在榆中及其周边地区推广养殖。     

无角陶赛特羊与藏系羊的杂交试验

用引进的无角陶赛特羊与藏系羊的杂交试验,结果表明：陶藏F1具有初生重、生长发育快、产肉性能好的优点。陶藏F1初生重、3月龄、6月龄重分别比当地藏系羊提高1．12kg,5．50kg,和10．00kg,陶藏F1日增重比藏系羊增加24．95g,体高、体长、胸围、管围明显高于藏系羊。     

Year-round breeding of crossbred Dorset or Finnish landrace ewes using a synthetic light regimen

A group of crossbred Dorset or Finnish Landrace ewes maintained under a synthetic light regimen (Light Treatment, 4 mo long days - 16 h light, 4 mo short days - 8 h light) and exposed to rams every 8 mo (January 1, September 1, May 1) was compared for lamb production over a period of 4.5 yr with two other comparable groups under natural daylight conditions, one exposed to rams once a year in the fall (Control I) and the other every 8 mo (Control II). Conception rates across breed type of ewe were 92% for Control I, 66% for Control II and 83% for Light Treatment ewes. Conception rates for May breedings only were 16% in Control II and 88% in Light Treatment ewes. Prolificacies of crossbred Finn ewes were higher (P less than .05) than those in crossbred Dorset ewes of Control I (258 vs 193%), Control II (187 vs 165%) and Light Treatment (238 vs 163%). The annual production at lambing from the crossbred Finn and Dorset ewes in Control I was 251 and 206 lambs/100 ewes exposed to rams, respectively. Corresponding productions were 231 and 178 for Control II and 296 and 211 for Light Treatment ewes. Mortality of lambs from the crossbred Finn ewes (27%) was higher (P less than .01) than that from the crossbred Dorset ewes (12%). Annual attrition of the crossbred Dorset ewes in Control I, Control II and Light Treatment groups was 5.2, 5.4 and 5.4%, respectively. Corresponding percentages of the crossbred Finn ewes were 7.0, 8.8 and 11.2.(ABSTRACT TRUNCATED AT 250 WORDS)     

杜泊羊与巴彦淖尔多胎羊杂交F1代生产性能的研究

旨在研究杜泊羊与巴彦淖尔多胎羊杂交F₁代的生产性能,为新疆库尔勒地区引进巴彦淖尔多胎羊进行肥羔生产和肉羊杂交利用提供依据。试验比较了2017年与2018年同一饲养管理水平下杜泊羊（父本）与巴彦淖尔多胎羊（母本）杂交后代（杜×巴F₁代）和新疆库尔勒地区本地绵羊自然交配所生产的羔羊（对照组羔羊）之间在生长性能、屠宰性能等方面的差异,同时对巴彦淖尔多胎母羊和当地母羊的繁殖性能进行了对比分析。结果表明,2017年与2018年,杜×巴F₁代羔羊的3月龄及6月龄体重极显著（P<0.01）高于对照组羔羊,日增重显著（P<0.05）高于对照组羔羊;除2018年6月龄杜×巴F₁代羔羊体长、胸宽极显著（P<0.01）高于对照组羔羊外,2017年与2018年6月龄屠宰时杜×巴F₁代羔羊的体高、胸深、胸围、管围等体尺指标均显著（P<0.05）高于对照组羔羊;2017年和2018年,杜×巴F₁代羔羊的胴体重分别比对照组羔羊提高了21.07%和22.90%,差异均极显著（P<0.01）;2017年与2018年,杜×巴F₁代羔羊的净肉重、净肉率极显著（P<0.01）大于对照组羔羊;巴彦淖尔多胎母羊的难产率极显著（P<0.01）高于本地绵羊,羔羊成活率极显著（P<0.01）低于本地绵羊,但其受胎率显著（P<0.05）高于本地绵羊,产羔率、双羔率分别比本地绵羊提高了24.72%和3.41倍,差异均极显著（P<0.01）。综合以上结果可以得出,杜×巴F₁代羔羊的生长性能、屠宰性能均优于对照组羔羊,继承了父本杜泊羊优良的生长发育性能;母本巴彦淖尔多胎羊保持了对环境的良好适应性和多胎性。在该地区引入巴彦淖尔多胎母羊,并与杜泊公羊进行杂交,充分利用杜×巴F₁代羔羊的杂种优势,将明显提高该地区肉羊养殖的经济效益。     

肉羊不同杂交组合效果试验研究

本试验主要对甘肃省近年引进的不同品种肉羊杂交后代的生长发育及适应性进行了观察研究,本试验主要以南非美利奴羊（萨门）、陶赛特羊、特克赛尔羊及杜泊肉羊作为父本,以小尾寒羊母羊,进行杂交,对杂交后代的生长发育及生产性能进行了观察研究,本试验根据各场存栏杂种肉羊的品种及数量,设立6个试验组和一个对照组。按期对试验羊只初生、3月龄、6月龄体重、体尺进行测定,并对成年母羊的配种产羔情况进行统计分析。试验得出：（1）以萨门、陶赛特、特克赛尔及杜泊肉羊作为父本,对我省各地绵羊杂交,后代杂种优势明显,适应性强,耐粗饲,在外貌、生长、产肉、繁殖性能及羊肉品质等方面均有提高。（2）杂种肉羊繁殖性能也较纯种肉羊有所提高。（3）试验证实杂交后代实现肉羊杂交育种、优质羊肉生产和实现肉羊产业的有效途径。     

无角陶赛特改良蒙古羊的效果分析

采用随机抽样的方法,对甘肃省永昌县引进的肉羊品种无角陶赛特杂交改良蒙古羊的杂种F1（DMF1）、F2（DMF2）F3（DMF3）在不同年龄阶段通过测定体重体尺指标,以当地蒙古羊（M）为对照进杂交效果的分析。结果表明杂种后代的主要生产性能均优于蒙古羊,无角陶赛特杂交改良蒙古羊杂交效果显著,在条件允许的情况下可以对当地蒙古羊进行大规模杂交,尤其是高代杂交经济效应更为显著。     

A comparison of Dorset and Finnish Landrace crossbred ewes

Data from 644 exposures and 552 lambings were used to analyze reproductive traits of 1/2-Finnish Landrace, 1/2-Dorset ewes (1/2 Finn); 1/4-Finnish Landrace, 3/4-Dorset ewes, (1/4 Finn) and Dorset ewes. Ewes were exposed to Hampshire or Suffolk rams for spring lambing from 1973 to 1978. The analytical model included fixed effects of ewe birth year (EBY), ewe breed (BR), lambing year within EBY and EBY X BR interaction and random effects of ewe within EBY and BR. Conception rate differed (P less than .01) for 1/2-Finn (.94), 1/4-Finn (.88) and Dorset (.80) ewes. Litter size was highest (P less than .01) for 1/2-Finns (1.97), followed by 1/4-Finns (1.74) and Dorsets (1.44). The 1/2-Finn ewes ranked first for number and weight of lambs weaned, and for number and weight marketed as feeder lambs. Birth weights were heavier (P less than .001) for lambs with Dorset dams (3.88 kg) than for lambs with 1/4-Finn (3.24 kg) or 1/2-Finn (3.08 kg) dams. Preweaning average daily gains and adjusted 90-d weights were also larger (P less than .001) for lambs with Dorset dams (.26 kg/d and 28.3 kg, respectively) than for lambs with 1/4-Finn (.24 kg/d and 25.4 kg) or 1/2-Finn (.24 kg/d and 25.1 kg) dams. However, Dorset ewes lambed an average of 10.5 d later than Finn-cross ewes, and actual weaning weights (unadjusted for age) did not differ significantly among lambs from Dorset (27.2 kg), 1/4-Finn (26.9 kg) and 1/2-Finn ewes (26.7 kg).(ABSTRACT TRUNCATED AT 250 WORDS)