浅谈牦牛的种间杂交改良问题

应用三元杂交的方法，将杂种藏黄公牛（黑白花冻精×藏黄牛）与牦牛自然交配，其繁殖成活率达４１．４１％，比用“冻配”技术生产犏牛的繁殖成活率提高２０．８９个百分点，Ｆ１母犏牛第一胎头平产奶量６０３．９ｋｇ，为同胎次母牦牛的２．４３倍。Ｆ１母犏牛２～３岁时可初配，比母牦牛提前１～２岁挤奶。Ｆ１公犏牛３．５岁可役用或屠宰，比阉牦牛提前１～２岁。建议在牦牛分布区，大力推广牦牛的三元杂交。     

牦牛同期发情及定时授精技术的试验

53头青年母牦牛和42头当年产母牦牛进行同期发情及定时授精处理,其中青年母牦牛人工授精31头,当年产母牦牛人工授精28头,人工授精精液采用大通牦牛冻精和西门塔尔牛冻精,输精一次后母牦牛与公牦牛合群放牧。结果青年母牦牛产犊率为84.91%,产大通牦牛后代10头,西门塔尔杂种犏牛1头,采用大通牦牛精液和西门塔尔精液人工授精情受胎率分别为58.82%(10/17)和7.14%(1/14);当年产母牦牛产犊率为52.38%(28/42),产大通牦牛后代11头,西门塔尔杂种犏牛2头,人工授精情受胎率分别为45.83%(11/24)和50%(2/4);2组平均人工授精情期受胎率为42.37%,其中用大通牦牛冻精的人工授精情期受胎率为51.22%,西门塔尔牛冻精的情期受胎率为16.67%。     

娟姗牛冻精人工授精甘南母牦牛辅助繁殖技术的优化与应用

人工授精技术已成为改良甘南牦牛的关键辅助性繁殖技术手段，研究发现娟姗牛是甘南母牦牛杂交改良的最佳父本，因此建立了一套标准化、易于操作的娟姗牛冻精人工授精甘南母牦牛的辅助生殖技术，对当地牦牛种质资源创新利用具有重要意义。本研究从待配母牦牛个体的筛选、群体的组建、饲养与管理、冻精质量与受精潜能的评估、牦牛发情临床鉴定、人工授精标准程序、妊娠诊断与管理等环节，对娟姗牛冻精人工授精甘南母牦牛的标准进行完善，在夏河县多家牦牛养殖合作社进行推广应用，并通过比较授精技术优化前后母牦牛的产道疾病、受胎率与产犊率，分析牦牛生产效果。结果显示，娟姗牛冻精人工授精甘南母牦牛辅助繁殖技术优化后，牦牛发情鉴定准确率高达85.98%，群体受配后整体妊娠率为85.86%，产犊率为92.09%，与传统授精技术相比显著提高；且授精后牦牛产道疾病发生率及胎衣不下、子宫脱出等围产期疾病发生率显著降低，说明优化后娟姗牛冻精人工授精甘南母牦牛技术可显著提升牦牛杂交改良的生产效果。     

甘南牦牛杂交改良现状与措施

甘南牦牛应突出肉用价值,把肉当作主攻方向,作为主导支柱产品。开展牦牛与普通牛的种间杂交,是提高牦牛业生产水平和经济效益的重要途径。在二元杂交试验中,若杂交目的主要以生产肉或提高役力,改良牛的父本,应选择短角牛、夏洛来牛、西门塔尔牛、海福特等肉乳兼用和肉用良种牛,具有明显杂优效果;若杂交的目的主要是生产牛奶和酥油,则父本以黑白花奶牛等与牦牛交配产生黑犏杂一代的组合为最佳;若杂交的目的主要是奶肉兼用,则一代奶用二代肉用。甘南地区犏牛繁殖的主要目的是产奶。因此,牦牛种间杂交育种的主要方法是采用良种牛冻精(娟姗牛等)与母牦牛进行人工授精等方法生产良种犏雌牛。     

甘南牦牛不同杂交组合生产性能分析

为提高牦牛生产的社会、经济和生态效益,满足人们对无污染的牦牛奶、肉等绿色食品日益增长的需要,本研究利用娟姗牛、安格斯牛和野牦牛的冻精杂交改良甘南牦牛,筛选最佳杂交组合。结果发现,与当地牦牛相比,娟姗牛、安格斯牛和野牦牛与本地牦牛杂交的F1代公母犊牛的初生重、3月龄体重和6月龄体重均显著高于本地牦牛犊(P<0.05),其中娟姗牛、安格斯、野牦牛的杂交F1代的公犊牛初生重分别提高了30.12%、18.21%和13.21%;3月龄体重分别提高了7.89%、3.70%和1.94%;6月龄体重分别达到了81.26±1.23kg、79.26±1.04kg和78.42±1.13kg,而母犊牛6月龄体重分别为77.78±2.26kg、78.07±1.97kg和75.85±1.32kg。因此,利用娟姗牛、安格斯牛与牦牛种间杂交育种可显著改善犏牛生产性能,这将为提高甘南牦牛生产性能、生产优质牛肉提供依据。     

不同父本冻精杂交甘南牦牛母本围产期疾病发生率分析

[目的]为提高甘南农牧交错区牦牛生产性能筛选最佳杂交父本。[方法]分别选取荷斯坦奶牛、西门塔尔、安格斯、娟姗牛优质冻精杂交甘南牦牛,比较妊娠牦牛的流产率、难产率,产后胎衣不下、子宫内膜炎症的发生率,产后当年与第二年发情的比率。[结果]荷斯坦奶牛、西门塔尔冻精人工授精甘南牦牛时,母本妊娠期的流产率和难产率显著高于安格斯、娟姗牛(P<0.05),荷斯坦奶牛、西门塔尔、安格斯作为父本杂交,母本的产后胎衣不下、子宫内膜炎症发病率显著高于娟姗牛(P<0.05)。娟姗牛冻精人工授精甘南牦牛,母本产后当年与第二年发情的比率分别为39.22±1.65%和35.29±1.84%,显著高于其他种公牛冻精杂交后母本的发情率,且只有娟姗牛试验组当年发情率高于第二年发情率。[结论]娟姗牛为父本时,围产期疾病发生率最低,繁育潜能利用率最高,可作为改良甘南牦牛最佳父本。     

公野牦牛的繁殖特性

研究首次对野牦牛的精液品质、精子超微结构、精液精子酶活力等项指标进行了测定,发现具有以下特点精子密度大,每毫升精液含精子21.3亿;精子存活时间长,0～4℃存活57小时,解冻后37℃条件下存活12小时;抗力系数144 000;解冻后精子畸形率和顶体完整率分别为9.17%、87.53%;精液运动粘度为1.69 cP;总氮量为1437.7 mg/100 ml;精子头短尾长,与家牦牛及黄牛差异显著或极显著;精子透明质酸酶活力极显著高于家牦牛,LDH活力比家牦牛高48%.因此,公野牦牛具有高繁殖力,与家牦牛冻配受胎率达88.9%;与普通牛种(黄牛)反杂交冻配受胎率达71.58%.家畜繁殖力的研究侧重于母畜,公畜繁殖力除奶牛之外重视不足,特别是对于培养程度很低的原始育种--牦牛,至于初步驯化的公野牦牛的繁殖力研究在国内外尚属空白.公畜繁殖力主要表现于精液品质和受胎率,许多学者从精子的生理生化特性和超微结构的改变测定与受胎率的相关性.野牦牛(Bos mutns)是家牦牛(Bos grannies)最近的祖先,在分类上是同属同种的不同亚种,野牦牛是"优势型"的"原生亚种",家牦牛是退化了的"驯化亚种".从1984年开始在青海省大通牛场驯化了两头公野牦牛,采用假阴道采精并试制了颗粒冻精.1984～1998年14年野牦牛冻配家牦牛近40 000头,受胎率88.9%,繁殖成活率85.97%.公野牦牛不但与同属同种的家牦牛冻精配种中表现出了很高的繁殖力,而且和普通牛种黄牛杂交也表现出了较高的受胎率.甘肃省礼县畜牧中心1987年开始连续3年购进野牦牛冻精授配黄牛771头,杂交生产野血牦犏牛554头,繁殖率高这71.85%,犊牛生活力强,产生了明显的经济效益.     

青海牦牛和藏羊冷冻精液顶体完整率研究

为了研究牦牛、藏羊离体精子遭受低温打击和冷冻伤害差异,试验对牦牛、藏羊的鲜精采用最佳的冷冻程序进行细管冻精,比较其鲜精及冻后精子顶体完整率差异,并分析冻后精子顶体完整率降低的原因。结果表明:牦牛的冻精顶体完整率显著低于藏羊的(P0.05)。牦牛精子冷冻后,精子顶体完整率为53.92%,较鲜精精子顶体完整率降低30.90个百分点;藏羊精子冷冻后,精子顶体完整率为84.93%,较鲜精精子顶体完整率降低8.53个百分点。牦牛离体精子抗低温打击和冷冻伤害能力显著低于藏羊。     

麦洼牦牛远缘杂交繁殖效能初探

在进行麦洼牦牛远缘杂交繁殖过程中,授配率与受胎率差异显著(p<0.05),表明授配率高,受胎率亦高;未受胎牛体重极显著大于受胎牛体重(p<0.01),证明维持母畜适当膘度,是保证正常发情、受胎生理的物质基础;精液精子活力与受胎率差异极显著(p<0.005),证明精于活力是麦洼牦牛远缘杂交受胎率的重要因素;对发情母牦牛不同发情时期输精,受胎率差异极显著(p<0.01),由此表明,适时输精对受胎有极其明显的作用。从而展示了麦洼牦牛远缘杂交受胎率是综合因素作用的结果。因此,在麦洼牦牛远缘杂交繁殖过程中,绝对不能片面强调某一个因素的作用,忽视其他因素的作用。     

浅谈牦牛的种间杂交改良问题

四川应用三元杂交的方法，将杂种藏黄公牛与牦牛自然交配，其繁殖成活率达４１．４１％，比用“冻配”技术生产犏牛的繁殖成活率提高２０．８９百分点，Ｆ１代母犏牛第一胎头平产奶量６０３．９ｋｇ，为同胎次母牦牛的２．４３倍。Ｆ１母犏牛２－３地可初配，比母牦牛提前１－２岁挤奶。Ｆ１公犏牛３．５岁可役用或屠宰，比阄割牦牛提前１－２岁，为使牦牛杂种优势在其商品中发挥应有作用，建议在牦牛分布区，大力推广牦牛的“三元杂     

免疫技术提高牦牛种间杂交受胎率

用黑白花公牛精液经皮下注射家兔或牦年犊,均可获得交高滴度的血清精子抗体;用分离纯化获得的精子抗体（ＩｇＧ）强化免疫异种莴种;家禽可获得血清精子抗抗体。精子抗体和精子抗抗均具有较强的专一性。有子抗体和精子抗抗体分别进行主动免疫或被动免疫防治母牦牛免疫不孕能显著提高牦牛种间杂交的台率（分别２７．９５％和２２．２１％）,获得显著的经济效益。     

胚胎期高温处理对家蚕生长发育及部分经济性状的影响

用 3 4℃、RH80 %的环境处理 2 0余个家蚕品种的己 + 2 期胚胎 ,结果表明 :高温处理对某些品种的幼虫经过、幼虫体重、全茧量、茧层量等有明显影响 ,对健康性、茧层率无明显影响 ,对丝质无实质影响 ;高温处理对家蚕生长发育和经济性状的影响纯种间存在差异 ,杂交种受影响比纯种小。因此认为 ,高温处理对家蚕生长发育、经济性状的影响不会成为伴性温敏基因和雄蚕品种利用的限制因素 ,部分不良影响可以通过常规育种手段加以解决     

晋阳肉兔配套系杂交效果研究

对以新西兰白兔、加利福尼亚兔为基础群经过 3个世代纯种选育的父系 (晋 系 ) ,母系(晋 系 )进行配合力测定 ,结果表明 :在 CP1 6.1 3%、CF1 4.57%的中等偏下营养条件下 ,晋 系×晋 系、晋 系×晋 系、晋 系×晋 系 ,42～ 77日龄平均日增重分别为 2 6.62 g、2 6.1 0 g和30 .2 3g,日增重的杂种优势率为 1 4.68%( P<0 .0 1 ) ;料肉比分别为 3.1 6∶ 1、3.37∶ 1和 2 .82∶ 1 ,料肉比的杂种优势率为 1 3.63%( P<0 .0 1 ) ;屠宰率分别为 54.1 2 %、56.2 1 %和 55.79%,屠宰率的杂种优势率为 1 .1 3%( P>0 .0 5)。     

Comparison of density gradient and single layer centrifugation of stallion spermatozoa: Yield,motility and survival

Reasons for performing study: A new, simpler, technique of colloidal centrifugation has recently been developed, designated single layer centrifugation (SLC). This technique requires evaluation by comparison with a density gradient for its ability to select the best quality spermatozoa and its practicality of use on studfarms. Objective: To compare the effect of 2 methods of colloidal centrifugation, density gradient centrifugation and single layer centrifugation, on stallion sperm motility, yield and survival, using freshly collected extended stallion semen. Methods: Aliquots of extended stallion semen from 10 stallions (38 ejaculates) were processed by the 2 methods of colloidal centrifugation. For both uncentrifuged and centrifuged samples, sperm yield was calculated and subjective sperm motility assessed over several days to provide an estimate of sperm survival. Some stored semen samples, held at 4°C overnight, were also available for testing. Results: For fresh, extended semen, a similar recovery yield of motile spermatozoa was seen for the 2 methods of preparation for single layers and density gradients, respectively. Sperm motility and survival rate were significantly improved by colloidal centrifugation compared to unprocessed ejaculate, without any significant difference between methods (SLC vs. gradient). However, the yield was reduced by 18–20% when cold‐stored semen was used for centrifugation compared to fresh semen; and more variation between ejaculates was observed than for fresh ejaculates. Again, sperm motility and sperm survival were improved in the centrifuged sperm preparations compared to stored, unprocessed ejaculates. Potential relevance: The 2 colloid centrifugation techniques produce equivalent sperm preparations in terms of sperm quality. However, the SLC method would be more practical and convenient for use in the field.     

The effect of two pre-cryopreservation single layer colloidal centrifugation protocols in combination with different freezing extenders on the fragmentation dynamics of thawed equine sperm DNA

Background

Variability among stallions in terms of semen cryopreservation quality renders it difficult to arrive at a standardized cryopreservation method. Different extenders and processing techniques (such us colloidal centrifugation) are used in order to optimize post-thaw sperm quality. Sperm chromatin integrity analysis is an effective tool for assessing such quality. The aim of the present study was to compare the effect of two single layer colloidal centrifugation protocols (prior to cryopreservation) in combination with three commercial freezing extenders on the post-thaw chromatin integrity of equine sperm samples at different post-thaw incubation (37°C) times (i.e., their DNA fragmentation dynamics).

Results

Post-thaw DNA fragmentation levels in semen samples subjected to either of the colloidal centrifugation protocols were significantly lower (p<0.05) immediately after thawing and after 4 h of incubation at 37°C compared to samples that underwent standard (control) centrifugation. The use of InraFreeze® extender was associated with significantly less DNA fragmentation than the use of Botu-Crio® extender at 6 h of incubation, and than the use of either Botu-Crio® or Gent® extender at 24 h of incubation (p<0.05).

Conclusions

These results suggest that single layer colloidal centrifugation performed with extended or raw semen prior to cryopreservation reduces DNA fragmentation during the first four hours after thawing. Further studies are needed to determine the influence of freezing extenders on equine sperm DNA fragmentation dynamics.     

Reproductive season and male effect on quantitative and qualitative traits of individually collected Muscovy duck (Cairina moschata) semen

Males of Muscovy duck (Cairina moschata) are mainly used for mule duck production via artificial insemination of females originated from wild mallard duck (Anas platyrhynchos); therefore, the quantity and quality of drake semen play a crucial role. The assessment results of male reaction to sexual stimulation by dummy female and basic semen characteristic (ejaculate volume, sperm concentration and morphology) of 12 individually kept Muscovy drakes carried out during the entire reproductive season are described. The male and period of the reproductive season effect on scored semen traits are documented. In total, 792 individual semen collections and evaluations were performed. The average of positive reaction in the entire reproductive season varied from 90.6% in December and April to 50.0% in July, while for individual males, it varied between 97.1% and 29.0%. Throughout the season, the ejaculate volumes ranged from 0.05 to 2.45 ml, sperm concentration from 0.15 × 10⁹ ml⁻¹ to 4.44 × 10⁹ ml⁻¹, total number of live spermatozoa from 68.0% to 100% and live normal (properly formed, with any deformations) from 51.0% to 99.0%. Our study indicates the necessity of male breeders pre-selection before the onset of the reproductive season, and the need to leave an appropriate number of males to ensure adequate amount of semen for female insemination, especially when using Muscovy drakes (Cairina moschata) for interspecies crossing with Anas platyrhynchos ducks.     

气候因素对公犬采精量及精液品质的影响

随机选取南方某犬场使用的德国牧羊犬种公犬16头,对该批种公犬在2011年度所采集的精液量及精液品质进行统计,发现当地的气候(气温、降雨量)变化对公犬采精量及精液品质有直接影响。结果表明,公犬精液品质会随着采精月份及季节的不同而发生一定变化,夏季高温环境对公犬精液品质影响较大,精液品质下降;精子活力、精子密度及精子畸形率与气温的变化呈中等相关(P<0.1),射精量与气温变化的相关不明显(P>0.1),而射精量与降雨量的变化呈中等相关(P<0.1),与其它性状相关不明显(P>0.1)。     

动物精液品质评定方法的研究进展

人工授精和体外受精技术的广泛应用,使精液保存技术得到了快速发展。精子的质量和功能状态直接影响其受精能力。文章综合阐述了近几年动物精液品质评定的方法:精子质膜完整性检测、线粒体活性的测定、受精能力的检测和精液中酶活性的测定。     

Multivariate Cluster Analysis Regression Procedures as Tools to Identify Motile Sperm Subpopulations in Rabbit Semen and to Predict Semen Fertility and Litter Size

Computerized motility analysis (CASA) shows that four separate subpopulations of spermatozoa with different motility characteristics co-exist in rabbit ejaculates. There were significant (p < 0.01) differences in the distribution of these subpopulations among separate genetic lines, total sperm abnormalities and the percentage of altered acrosomes. Furthermore, logistic and linear multivariate regressions among several parameters of rabbit semen quality analysis were tested for use as predictive tools for the fertilizing ability of a specific artificial insemination semen sample. Logistic regression analysis rendered two mathematical, significant (p < 0.01) models: one between sperm viability and conception rate and the other between total sperm abnormalities and conception rate. Multiple linear regression analyses also yielded some significant relationships between both fertility (p < 0.001) and litter size (p < 0.05), with respect to some semen characteristics. Our results support the hypothesis that the predictive in vivo fertility use of the standard rabbit semen quality analysis coupled with a CASA determination could be reasonably achieved by applying linear and logistic regression analyses among several parameters of rabbit semen quality analysis.