欧拉羊与甘南山谷型藏羊杂交羔羊屠宰试验

通过对欧山F1和山谷型藏羊羔羊进行屠宰试验,结果得出:9月龄欧山F1羔羊宰前平均活重为38.25 kg,比本地山谷型藏羊羔羊宰前平均活重高10.17 kg,差异极显著(P<0.01)。欧山F1羔羊胴体重和屠宰率分别为15.14 kg和39.58%,比对照组高4.58 kg(P<0.01)和1.96个百分点,差异极显著。欧山F1羔羊净肉率、后腿比例和腰肉比例分别为29.65%、38.18%和12.99%,高于山谷型藏羊4.01、7.78和2.68个百分点;欧山F1羔羊GR值和眼肌面积分别为8.23 mm和12.74 cm2,高于山谷型藏羊1.48 mm和4.38 cm2。     

欧拉羊杂交改良甘加羊效果分析

在相同的自然条件下,欧杂(欧拉羊×甘加羊)F1初生重、0～180日龄平均日增重公羔为4.56 kg和138.11 g/d,母羔为4.28 kg和125.72 g/d,均显著高于甘加型藏羊的相应指标,差异极显著(P＜0.01).3、6、18月龄欧杂F1的体重增加明显,差异极显著(P＜0.01);体高、体长、胸围均高于甘加羊,差异显著(P＜0.05).     

欧拉型藏羊改良天祝草地型藏羊效果分析

为研究欧拉羊杂交改良天祝草地型藏羊效果,对欧拉羊与天祝草地型藏羊杂交试验组和天祝草地型藏羊本交对照组所产后代的初生、3月龄、6月龄、18月龄的体重体尺进行了跟踪测定,并对不同年龄段杂交后代与对照组后代进行了对比分析.结果表明：在相同的饲养管理条件下,欧杂（欧拉羊×草地型藏羊）F1公羔初生重、0～180日龄平均日增重分别为4.56 kg和138.11 g,母羔分别为4.28 kg和125.72 g,均极显著高于天祝草地型藏羊（P＜0.01）.3、6、18月龄欧杂F1的体重均明显增加,差异均极显著（P＜0.01）;体高、体长、胸围均高于天祝草地型藏羊,差异均显著（P＜0.05）.因此,欧拉型藏羊是改良天祝草地型藏羊的首选类群.     

日粮营养水平和品种对羔羊育肥效果的影响

试验以小尾寒羊为母本,以夏洛莱羊、无角陶赛特羊和小尾寒羊为父本,研究了夏洛莱羊(♂)×小尾寒羊(♀)、无角陶赛特羊(♂)×小尾寒羊(♀)和小尾寒羊(♂)×小尾寒羊(♀)3个组合的F1饲喂不同蛋白水平饲粮后75日龄时羔羊的体重。结果表明:3个组合中,F1体型外貌均与其父本相似;饲喂高蛋白水平饲料的羔羊75日龄体重极显著高于饲喂低蛋白水平饲料的羔羊75日龄体重(P<0.01);夏寒杂交羊和陶寒杂交羊的75日龄体重均极显著高于小尾寒羊(P<0.01),夏寒杂交羊的75日龄体重极显著高于陶寒杂交羊(P<0.01)。品种和饲料对75日龄体重也有交互作用(P<0.05)。     

高寒牧区羔羊短期育肥效果

在青海省刚察县哈尔盖镇察拉村随机选择6月龄藏系羔羊60只和陶×藏杂一代羔羊30只进行60 d同品种羔羊短期育肥试验和不同品种羔羊短期育肥试验。结果表明：藏系羔羊在放牧＋补饲饲养管理下,比纯天然放牧生长发育快,只均日增重高出46.4 g,且差异极显著（P〈0.01）;陶×藏杂交羔羊生长速度快,杂种优势显著,只均日增重高出放牧＋补饲藏系羔羊47.3 g,差异也极显著（P〈0.01）。     

陶赛特羊与青海藏羊杂交改良试验

利用陶赛特与青海藏羊进行杂交改良，经测定：杂一代羔羊初生重、1月龄、3月龄、6月龄体重、日增重极显著高于藏系羔羊（P＜0.01)；陶藏杂一代产肉性能极显著高于藏系羊（P＜0.01)。     

高寒条件下无角陶赛特羊与青海绵羊杂交改良试验

试验结果表明 ,在高寒条件下 ,无角陶赛特羊与青海绵羊杂交一代的初生、1月龄、2月龄、3月龄、4月龄、5月龄体重显著高于青海羔羊 (P <0 .0 5 )。 169日龄陶杂一代、青海羔羊进行为期 80d的补饲育肥 ,陶杂一代的总增重、日增重及胴体重分别为 15 .90kg、9.70kg和 18.2 9kg ,显著高于青海羔羊 (P <0 .0 1) ;陶杂一代的屠宰率也有所提高。每只陶杂一代比青海羔羊增收 93 .3 8元     

高寒地区陶赛特羊与青海半细毛羊杂交试验效果分析

引进陶赛特绵羊与青海半细毛羊进行杂交试验,羔羊8月龄时随机抽样屠宰。经测定陶半F1代羊宰前活体重、胴体重和平均日增重分别为34.33kg、14.49kg和124.68g,比青海半细毛羊分别提高14.07%、20%和12%,差异极显著(P<0.01);陶半F1代羊各月龄段的体尺均优于青海半细毛羊。据市场价估算,每只陶半F代羔羊纯收入可增加34.8元,经济效益可观。     

无角陶赛特杂交藏系羊的效果分析

本研究通过2个试验测定无角陶赛特与藏系羊杂交的效果。结果表明,在放牧条件下陶藏F1初生重3.61kg,较藏羊高0.34kg,以后各统计阶段陶藏F1均极显著高于藏羊（P〈0.05）,周岁陶藏F1体重较藏羊高5.25kg。短期育肥后陶藏F1体重、净增重均较藏系羊羔,日增重185.33g/d,极显著高于藏系羊（P〈0.01）。表明无角陶赛特杂交改良藏系羊优势明显,能显著提高生长速度和产肉性能。     

引进优良品种肉羊与藏羊不同杂交组合效果

本试验使用国外优良品种肉羊杜波、特克赛尔、萨福克、澳洲白及陶赛特细管冻精,应用腹腔镜子宫角人工授精技术受配当地藏羊,开展以藏羊为母本的不同杂交组合试验,对不同杂交组合F1代生长发育和适应性进行观察测定。结果表明:在同等放牧条件下,萨×藏、杜×藏和特×藏组合F1代初生重分别为4.04 kg、4.58 kg和4.18 kg,3月龄体重分别为23.22 kg、23.10 kg和22.97 kg,显著高于当地藏羊(P<0.05);3月龄F1代体高、体斜长与当地藏羊无显著差异,但胸围明显提高,分别达到72.54cm、72.12cm和71.85cm,差异显著(P<0.05)。结果证实,以杜波、特克赛尔及萨福克肉羊作为父本对当地藏羊进行杂交改良,F1代适应性好,杂种优势明显,放牧采食能力较强,在日增重、生长发育和体型外貌等方面较当地藏羊均有显著提升和改善,养殖效益明显高于当地藏羊。     

半胱胺对藏绵羊断奶羔羊血清GH、SS、IGF-1水平的影响

试验研究了半胱胺(CS)对藏绵羊断奶羔羊血清中生长激素(GH)、生长抑素(SS)、血清中胰岛素样生长因子(IGF-1)的影响。将40只80日龄左右且始重平均为16 kg的(公母各半)藏绵羊断奶羔羊随机分为2组,在日粮精料中添加300 mg/(kg·BW)的CS,隔日添加1次,试验期42 d。分别于开始用药后的第0、7、14、21、28、35天早晨空腹颈静脉采血样,以放射免疫法测定血浆中GH、SS、IGF-1。结果表明,试验组精料中添加CS使藏绵羊断奶羔羊血清GH、IGF-1都有不同程度的提高,且试验组与对照组相比都有显著差异(P0.05);SS均有不同程度的下降,试验组与对照组相比第3周开始有显著差异(P0.05)。     

高寒地区无角陶赛特与青海半细毛羊杂交一代羔羊生长发育模型

采用Gompertz模型、Logistic模型拟合了无角陶赛特与青海半细毛羊杂交一代羔羊和青海半细毛羔羊的早期生长发育过程。结果表明：2种模型的拟合度均在0.98以上,拟合效果好,其中Gompertz模型在拟合度和预测体重效果方面最好。因此,采用Gompertz模型进一步估算了杂一代羔羊的拐点体重、拐点日龄、相对生长率（RGR）、瞬时生长率（IGR）,结果表明：无角陶赛特杂一代羔羊早期生长发育强于青海半细毛羔羊。     

Genetic effects on ewe productivity of crossing D'man and Sardi breeds of sheep

Data from 364 ewes of Sardi (S), D'man (D), S x DS, DS x S, S x D, D x S (F1), F2, D x DS and DS x D breed groups mated to F1 rams were analyzed for fertility, number of lambs born alive, litter size at weaning, litter weight at weaning per ewe joined and mean lamb weight at 60 d. Each ewe was exposed in two seasons and had one or two lambings. Effects of breed group were significant for all traits. The highest number of lambs born alive and litter size at weaning were recorded in D'man (1.84 and 1.45, respectively) and D x DS (1.81 and 1.43, respectively). F1 ewes (S x D and D x S) had the highest fertility (.94) and litter weight at weaning per ewe exposed (13.8 kg). Mean lamb weight at 60 d was highest for S x DS and Sardi ewes (13.4 kg and 13.2 kg). D'man additive effects were positive and significant for number of lambs born alive, litter size at weaning and litter weight at weaning per ewe joined; were significant but negative for mean lamb weight at 60 d; and were not significant, although positive, for fertility. Significant individual heterosis was found for fertility, litter weight weaned and mean lamb weight at 60 d. Maternal heterosis and direct epistatic recombination effects were small for all traits.     

Effects of sheep and cattle alternate grazing on sheep parasitism and production

Production of sheep (nursing ewes) grazing alternately with cattle (growing weaned heifers) was compared to the production of sheep or cattle grazing alone (controls). Pasture production and sheep parasitism were also monitored. The herbage allowance was higher for the control heifers than for the alternate heifers, but the leaf to green material ratio (LGMR) was lower, and no difference on heifer growth was revealed (443 vs. 431g.d^-1, P = 0.54). The LGMR was higher for the alternate sheep (+3 points) than for the control sheep, except during the dry season, when the herbage density was lower. The effects of parasitism on the packed cell volume of alternate ewes and lambs were lower than those of control ewes and lambs. However, the infection of sheep by Cooperia sp. (better adapted to cattle) was significantly higher for the alternate sheep than for the controls, and some indication of cattle infection by Haemonchus contortus was suggested. The 70-day lamb weight was higher in the alternate grazing system than in the control (+0.76,+1.11 and+0.61kg for the dry, intermediate and rainy seasons, respectively), and the average 70-day lamb production per ewe exposed was 21.42kg in the alternate grazing system vs. 18.59kg in the control (P = 0.003).     

Effects of genetic and environmental factors on pre-weaning and post-weaning growth in West African crossbred sheep

Effects of genetic and environmental factors on pre-weaning and post-weaning growth were studied in West African crossbred sheep. Effects of lamb genotype (7/8 Sahelian–1/8 Djallonké, 3/4 Sahelian–1/4 Djallonké and 1/2 Sahelian–1/2 Djallonké; hereafter denoted 7/8Sa, 3/4Sa and 1/2Sa, respectively), parity, type of birth, sex of lamb and year-season of lambing on birth weight, weaning weight, 8-month weight and pre- and post-weaning growth rates were determined. At birth 7/8Sa and 3/4Sa lambs were heavier (p<0.01) than 1/2Sa lambs. Lambs born to first-parity ewes were lighter (p<0.01) at birth than lambs of older ewes. At weaning and 8 months of age, lambs born to fourth-parity ewes were heavier (p<0.05) than those born to ewes of the other parities. Parity did not have any significant effects on pre-weaning growth rate. Lambs born in the rainy season of 2001 were significantly heavier at birth and at 8 months of age than those born in the dry season of 2001/02, but there was no difference between the two groups at weaning. Pre-weaning growth rate was significantly faster in lambs born in the dry season of 2001/02 but the reverse was true for post-weaning growth rate.     

Evaluation of the South African Dorper as a terminal sire breed for growth,carcass, and palatability characteristics

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.     

半胱胺对藏绵羊断奶羔羊增重及饲料转化效率的影响

试验研究了半胱胺(Cs)对藏绵羊断奶羔羊增重、饲料转化效率的影响。将40只(公母各半)80日龄左右且体重平均为(16.00±0.31)kg的藏绵羊断奶羔羊随机分为2组(试验组和对照组),在日粮精料中添加300 mg/(kg·BW)的Cs,隔日添加1次,试验期42 d。分别于开始用药后的第0、7、14、21、28、35天称重,并记录各组所采食的精料量。试验结果表明,试验组精料中添加Cs使藏绵羊断奶羔羊35 d增重提高43.25%(P0.01),开始用药后的前7 d差异不显著,但8~35 d最为明显,以后随时间延长促生长效果逐渐减弱;精料/增重比下降43.33%。     

陶赛特、萨福克与小尾寒羊杂交产肉性能的改良效果

以萨福克羊、陶赛特羊为父本与小尾寒羊进行杂交,在同等饲养管理条件下,其萨寒F1、陶寒F1与小尾寒羊间在90 d育肥期内日增重差异极显著(P0.01);6月龄胴体重差异显著(P0.05),6月龄屠宰率差异显著(P0.05),萨寒F1与陶寒F1间差异都不显著(P0.05)。实验表明:萨寒F1、陶寒F1生长速度快、产肉性能高的优点已在其杂交后代身上体现出来,杂种优势显著。     

欧拉型藏羊羔羊育肥试验

本试验结果表明：欧拉型藏羊羔羊在秋季放牧加补饲料颗粒料,自由采食,短期育肥,10月龄平均体重和日增重分别达到46．22kg和243g（P〈0．01）,比对照组提高5．94kg和110．64g（P〈0．01）;体高、体长、胸围和胸宽分别比对照组提高2．29mm,3．42mm,2．77mm和1mm,增重和生长发育潜力较大;胴体重达到21．40kg,比对照组提高5．28kg（P〈0．01）,屠宰率达到47．45％,提高16．36％（P〈0．05）,羊多收入27．66元／只。     

Influence of macronutrients and polyethylene glycol on intake of a quebracho tannin diet by sheep and goats

We determined if supplemental macronutrients or polyethylene glycol (PEG) influenced intake of a tannin diet. Sheep (lambs 5 mo age, 36 kg) and goats (kids 7 mo age, 32 kg) were fed supplements high in either energy or protein or offered a choice between the two supplements before and after receiving a meal containing 15% quebracho tannin. The effect of PEG, a compound that attenuates the negative effects of tannins, was assessed by offering PEG while animals consumed the tannin diet for 4 h/d. Intake of the tannin diet was influenced by both macronutrients and PEG. Animals that chose their own supplements or that received the high-protein supplement, consumed more of the tannin diet than animals fed the high-energy supplement: 34 and 36 vs 31 g/kg(0.75) (lambs) and 41 and 39 vs 34 g/kg(0.75) (kids), respectively (P < 0.05). Animals supplemented with PEG ate much more of the tannin diet than unsupplemented animals: 70 vs 39 g/kg(0.75) (lambs) and 63 vs 34 g/kg(0.75) (kids), respectively (P < 0.001). Sheep and goats consumed more tannin food when given PEG than when supplemented with macronutrients (51 and 38 g/kg(0.75), P < 0.001). Sheep and goats offered a choice between supplements consumed more CP than animals fed the high-energy supplement and more ME than animals fed the high-protein supplement (P < 0.05). In so doing, they selected a combination of foods that yielded a more balanced intake of macronutrients, while achieving high levels of intake of the tannin food. Sheep and goats can be used as an environmentally safe and economically sound means to reduce the abundance of tannin-rich vegetation. Macronutrients and PEG enhance use of tannin-containing plants, which may increase production of alternate forages and create a more diverse mix of species in a plant community.