影响奶牛胚胎移植效果的主要因素分析

本研究分析了不同移植地点、受体牛来源、受体牛黄体位置、移植季节以及对受体牛实施尾椎硬膜外麻醉等对胚胎移植受胎率的影响。2013年9月~2015年3月,在内蒙古和北京地区移植奶牛胚胎745枚,平均受胎率为57.2%。内蒙古地区的A牛场胚胎移植受胎率(50.3%)低于北京地区的B牛场(65.5%)和C牛场(61.7%),且差异显著(P0.05),而同一地区的B牛场和C牛场之间差异不显著(P0.05);不同来源受体牛受胎率比较,新西兰荷斯坦牛受胎率(57.4%)略低于澳大利亚荷斯坦牛(65.4%)和中国荷斯坦牛(65.5%),但差异不显著(P0.05),而澳大利亚荷斯坦牛与中国荷斯坦牛受胎率差异也不显著(P0.05);受体牛不同黄体位置受胎率比较,左侧黄体受体牛受胎率(60.4%)略高于右侧(54.7%),但差异不显著(P0.05);移植季节对胚胎移植受胎率影响,以春季受胎率最高(71%),其次是冬季(63.2%),最低是秋季(60.6%),但不同移植季节的胚胎移植受胎率没有显著差异(P0.05);受体牛实施尾椎硬膜外麻醉的受胎率(66.7%)略高于未实施麻醉的受体牛(62.4%),但差异不显著(P0.05)。     

受体牛营养对黄体的影响及黄体等级对冻胚移植受胎率影响的试验研究

为了探讨受体牛黄体形成的影响因素及黄体质量对胚胎移植受胎率的影响,2004-2005年利用冷冻胚胎移植受体的受胎结果与受体牛黄体等级之间的关系进行分析.结果表明,营养是影响受体牛黄体等级的主要因素,饲喂全价饲料和单一饲料的黄体合格率为61.2%、35.4%,差异极显著(P《0.01).A、B级黄体受体移植受胎率为71.7%、63.9%,二者之间差异不显著(P》0.05).     

B超诊断技术在胚胎移植受体牛黄体鉴定中的应用

本试验选用150头育成牛进行同期发情,采用人工直肠检查法和超声波法检测黄体级别,对检查合格的受体进行单枚克隆胚胎移植。结果显示,同期发情处理牛112头有发情表现,直肠检测黄体合格牛89头,胚胎移植后51头妊娠,受胎率57.3%;超声波检测112头发情牛,其中26头符合要求,移植后24头妊娠,受胎率92.3%;二者差异显著(P<0.05)。因此,B超诊断可作为胚胎移植受体牛黄体鉴定中的一项辅助技术,能够显著提高受胎率。     

荷斯坦青年牛黄体直径对移植受胎率的影响

【目的】为了获得更多的纯种和牛,【方法】采用临床观察、直肠检查和B超检查筛选出114头荷斯坦牛作为受体牛,采用CIDR埋栓做同期发情,在发情后第7天用B型超声仪对受体牛黄体直径进行测量,对符合条件的受体牛进行胚胎移植,将不同黄体直径(corpus lutum diameter,CLD)分为3个组,分别为1≤CLD≤1.5、1.5CLD≤2.5和CLD2.5。在移植后第23天用B超做妊娠诊断,以便研究黄体直径对移植受胎率的影响。【结果】表明,选择114头牛做同期发情,发情率为96.5%(110/114);黄体直径1≤CLD≤1.5组、1.5CLD≤2.5组、CLD2.5组受胎率分别是44.44%(4/9)、45.95%(17/37)和42.11%(8/19),各组之间差异均不显著(P0.05)。【结论】说明黄体大小与胚胎移植受胎率没有直接相关性。     

不同等级黄体与水牛胚胎移植受胎率关系的研究

[目的]为了解胚胎移植过程中不同等级黄体与水牛胚胎移植受胎率之间的关系,为提高水牛受胎率提供依据.[方法]在水牛胚胎移植过程中,利用B超对受体卵巢进行扫描,确定黄体的有无并根据黄体大小对其分级.黄体直径在1.5 cm以上的定为A级,直径在0.8～1.5 cm之间的定为B级,直径在0.8 cm以下的定为C级.测定受体移植...     

黑头萨福克绵羊胚胎玻璃化快速冻胚移植效果分析

本试验应用玻璃化胚胎冷冻方法进行黑头萨福克绵羊胚胎冷冻和移植,比较了受体羊卵巢上黄体数量、受体羊的体况、移植胚胎的数量对受体受胎率的影响。受体羊卵巢上有一个黄体的移植受胎率42.7%与有2~3个黄体受体羊移植受胎率44.4%无显著差异;受体的体况对受胎率有显著影响,中上等(含中等)体况水平的受体的受胎率47.2%显著高于中下等的受体的受胎率43.0%(P0.05);使用玻璃化胚胎冷冻法的冷冻解冻胚胎移植受胎率54.2%显著高于常规胚胎冷冻法的冻胚移植受胎率44.0%(P0.05);移植1枚桑葚胚(1M)的受胎率47.5%略高于移植1枚囊胚(1B)的受胎率44.3%(P0.05)。因此,受体羊黄体数、冷冻桑葚胚和囊胚对胚胎移植受胎率没有显著影响,而受体中上等(含中等)体况水平和玻璃化胚胎冷冻法冷冻解冻胚胎移植受胎率显著提高。     

影响荷斯坦牛胚胎移植受胎率因素的研究

为进一步提高荷斯坦牛冷冻胚胎移植受胎率,本研究对西安市奶牛育种中心2009~2013年期间的胚胎移植数据进行统计分析,侧重讨论了黄体位置、胚胎日龄及移植季节对受胎率的影响。结果表明,三年平均胚胎移植受胎率为53%;左右黄体受胎率分别为52%、55%,不同黄体位置对受胎率影响不显著(P0.05);早期桑葚胚、致密桑葚胚、早期囊胚的受胎率分别为40%、56%、62%,胚胎发育阶段对受胎率影响显著(P0.05);春、秋、冬季受胎率分别为60%、48%、52%,移植季节对受胎率影响不显著(P0.05)。     

绵羊胚胎移植受胎率影响因素的研究

为研究探索绵羊胚胎移植受胎率的影响因素,针对不同体况受体、供受体发情时间差、胚胎质量、单侧卵巢黄体数量及移植胚胎数量等进行试验研究。结果表明:体况较好组、体况中等组、体况较差组受胎率分别为67.62%、63.44%、52.08%,三组之间差异不显著(P>0.05);发情同步差在0h、±6h、±12h的受胎率分别为72.73%,68.18%,66.67%,三组之间差异不显著(P>0.05);移植A级胚胎的受胎率(67.24%)高于B级胚胎的受胎率(42.86%),差异显著(P<0.05);1个黄体的受胎率为61.76%,2个黄体的受胎率比1个黄体的高出3.69%,两者之间差异不显著(P>0.05);移植两枚胚胎的受胎率(69.77%)高于移植一枚胚胎的受胎率(62.5%),但差异不显著(P>0.05)。     

胚胎移植同期发情处理受体牛对胎儿生长影响的研究

通过对直肠检查有功能性黄体的受体牛进行一次前列腺素同期发情处理,并在处理后第10天直检,确定卵巢的状态和受体牛的可利用率,同时测量受体牛和初生犊牛体尺.结果表明:可以用PG处理的受体牛占牛群46%,且右侧黄体比例(57%)高于左侧(43%)(P<0.01);受体牛的可利用率达64%;受体牛在药物处理后卵泡发生(直检时为黄体)与药物处理前黄体在同侧的比例高于异侧;受体牛体尺和胚胎移植初生犊牛体尺有不同程度相关性,为今后胚胎移植受体牛的选择提供借鉴.     

不同黄体大小对供体超排和受体移植成功率的影响

本试验分析了291头14～15月龄荷斯坦青年母牛不同黄体大小对供体超排的效果。比较了924头受体母牛不同黄体大小对胚胎移植后妊娠率的影响。结果表明,埋栓前,黄体1.2cm组超排效果和有效胚胎数较高。黄体较小的组超排效果稍差一些。1.5cm以上黄体组的结果居中。受体母牛在移植胚胎时,0.8cm以上黄体的受体均获得了较高的妊娠率。但1.5cm以上黄体的受体妊娠率更高一些。由此结论提出：在超排前,黄体的大小与母牛体内孕酮浓度的高低和超排效果有关。受体在移植胚胎前,只要黄体的大小能保证最低妊娠所需的孕酮浓度,均能保证较好的妊娠率。黄体较大时,妊娠率有增加的趋势。     

德系乳肉兼用型西门塔尔牛胚胎移植效果研究

[目的]建立德系乳肉兼用型西门塔尔牛群体,探索文山牛快速扩繁和生产性能提升技术。[方法]在马关县从600头文山黄牛、西本杂、安本杂和短本杂牛母牛中选择270头,用CIDR+PG法进行同期发情处理,选择黄体合格的受体,采用非手术法移植德系乳肉兼用型西门塔尔牛胚胎,在移植后60~90 d通过直肠检查法进行妊娠诊断,确定妊娠率,跟踪调查产犊情况,并测定胚胎移植所产犊牛的初生体重和主要体尺指标。[结果]受体牛同期发情处理270头,胚胎移植87头,妊娠28头,移植妊娠率32.18%;妊娠母牛中产犊17头,产犊率60.71%,产犊19头,成活16头,产犊成活率84.21%。公母犊牛平均的初生重33.00 kg,体高69.50 cm,体斜长62.19 cm,胸围72.69 cm,管围13.50 cm。[结论]首次在文山州开展了牛胚胎移植获得成功,杂交牛受体的移植妊娠率极显著或显著高于文山牛受体,秋季移植的妊娠率极显著高于春季和冬季的。提示以杂交牛为受体在秋季进行胚胎移植可有效提高移植成功率。     

Japanese Society for Animal Reproduction: award for outstanding research 2002. The development and prevalence of the transfer technique for frozen-thawed embryos of Japanese black beef cattle in Tochigi Prefecture

The conditions of embryo transfer by the stepwise method, in which frozen-thawed embryos are transferred on day 7 (day 0=onset of estrus), were investigated with the aim of increasing pregnancy rates in frozen-thawed embryo transfer. The use of a vaginal speculum to prevent bacterial infection when passing an embryo transfer gun through the vagina yielded a pregnancy rate equal to or higher than that with application of a sheath cover to the transfer gun. Administration of a sedative, xylazine, to recipient cattle for preventing movement at the time of embryo transfer improved the pregnancy rate. The influence of the time from thawing of frozen embryos to transfer and of the transportation of the recipient by truck upon pregnancy rate was investigated. Embryo transfer within 60 minutes after aspiration into a straw or transportation of the bovine recipient, 1.5 hours each way before and after transfer, had no influence on pregnancy rate. Relations of the embryonic developmental stage and morphological quality after thawing of frozen embryos to pregnancy rate were investigated in recipients of nulliparous Holstein heifers. The pregnancy rate increased as the embryonic developmental stage advanced from compacted morula, early blastocyst, and blastocyst in that order. The pregnancy rate obtained with blastocyst stage embryos was significantly (P<0.05) higher than that with compacted morula stage embryos, and there was no significant difference in pregnancy rates between excellent morphological quality and good morphological quality for compacted morula stage embryos. When correlation of luteal function and pregnancy rate was investigated in bovine recipients, pregnancy rate showed a tendency to increase with increasing blood progesterone (P) concentration on the day before (on day 6 after estrus) and the day of embryo transfer. The pregnancy rate in bovine recipients, which showed a blood P concentration of > or =2.5 ng/ml on the day before embryo transfer, was significantly (P<0.05) higher than that in those with a blood P concentration of <2.5 ng/ml. Pregnancy rate showed a tendency to increase with decreasing blood estradiol-17beta (E2) concentration on the day of embryo transfer. Activation of luteal function by administration of human chorionic gonadotropin (hCG) in cycling cattle was investigated for its effect on increasing pregnancy rate in bovine recipients. A follicle coexisting with cyclic CL ovulated and induced CL formed after injection of hCG 1,500 IU 5 days after ovulation. The blood P concentration was significantly (P<0.05) higher in the administration group than in the control group, and the blood E2 concentration rapidly decreased, showing a lower concentration than in the control group. These results suggest the possibility that the pregnancy rate could be improved by administration of hCG. Pregnancy rate following intramuscular injection hCG 1,500 IU was comparatively investigated in parous Japanese Black beef cattle receiving frozen-thawed embryos 7 days after estrus. Pregnancy rate was 67.5% in the group in which hCG was administered on day 6 after estrus, and was significantly (P<0.05) higher than that in the control group (45.0%) and the group in which hCG was administered on day 1 after estrus (42.5%), revealing that hCG administration facilitated pregnancy. Transfer of frozen-thawed embryos in the blastocyst stage within 60 minutes after the aspiration into a straw, with a vaginal speculum after administration of xylazine is suggested as a way of improving pregnancy rate in bovine recipients with favorable luteal function and in those with luteal function activated by administration of hCG on the day before embryo transfer.     

非繁殖季节胚胎移植受体绵羊妊娠效果影响因素的研究

在非繁殖季节应用CIDR法和Progestagen Sponge法对受体绵羊进行同期发情处理后,进行冷冻胚胎移植,研究不同同期发情处理方法、卵巢状况、胚龄、移植方法和移植时间对冷冻胚胎移植妊娠率的影响,以期为当地实现绵羊胚胎移植产业化提供理论依据和技术参考。结果表明:经同期发情处理后,绵羊在去栓后24~72 h集中发情,在去栓后36~48 h发情最为集中;CIDR法和Progestagen Sponge法的同期发情率分别为91.11%和87.78%(P>0.05),同期发情绵羊移植利用率分别为82.93%和78.48%(P>0.05);单侧卵巢上含有1个和2个黄体其妊娠率分别为46.07%和48.78%(P>0.05);桑椹胚和囊胚的妊娠率分别为49.25%和42.11%(P>0.05);腹腔镜法和手术法的妊娠率分别为45.16%和48.52%(P>0.05);11月和12月进行冷冻胚胎移植的妊娠率分别为50.76%和43.08%(P>0.05),该试验的绵羊冻胚移植妊娠率为46.92%,基本接近国内冻胚移植水平,但低于目前国内羊鲜胚移植妊娠率(50%~60%)。由此可以得出,不同同期发情处理方法、卵巢状况、胚龄、移植方法和移植时间对胚胎移植妊娠率的影响均无显著性差异(P>0.05),大规模群体羊同期发情时,可选价格便宜的Progestagen Sponge法;只要受体绵羊黄体质量好即可移植胚胎;为了减轻受体绵羊的应激反应,降低术后子宫粘连的发病率,可广泛应用腹腔镜法进行胚胎移植;该试验的绵羊冻胚移植妊娠率低于目前国内羊鲜胚移植妊娠率,通过筛选高效低毒的抗冻保护剂,以及提高基层技术人员操作水平,则有望进一步提高绵羊冷冻胚胎移植妊娠率。     

鲜整胚及分割双半胚移植试验研究

本试验结合我省胚胎移植的现状,用7头纯种西门塔尔牛作供体,46头杂交牛作受体,进行同期发情和超数排卵,获得鲜整胚59枚,双半胚32枚;用鲜整胚22枚,双半胚24枚进行移植,研究鲜整胚与分割双半胚的移植效果。结果表明:鲜整胚单枚移植妊娠率为27.3%(6/22),分割双半胚移植妊娠率为54.2%(13/24),鲜整胚单枚移植妊娠率比分割双半胚移植妊娠率低26.9个百分点,经t检验差异显著(P<0.05)。     

Asynchronous Embryo Transfer in Sheep:Lack of Survival in Progestinized Recipient Ewes

Synchronization of development between the embryo and uterus is required for successful pregnancy establishment.Transfer of early embryos requires synchrony with the recipient uterus of 2 days or less in sheep,because asynchrony of 3 days or more results in failure of pregnancy recognition signaling for maintenance of corpus luteum (CL) and progesterone (P4) production and/or uterine support of the embryo.The objective was to determine if P4 treatment of recipient ewes would obviate the need for pregnancy recognition signaling and maintain a uterine environment conducive to embryo survival after asynchronous transfer,thereby establishing a universal recipient.Embryos (morulae/blastocysts) were recovered on day 6 from super-ovulated donor ewes.Recipient ewes received 25 mg P4 daily from day 6 post-estrus until 60 days after embryo transfer.Embryos were transferred into recipients on day 6,9,12,18,or 30 post-estrus.The pregnancy rate on day 22 post-transfer was 60% for synchronous transfers to day 6 ewes,44% and 22% for asynchronous transfers to day 9 and 12 ewes,and 0% for asynchronous transfers to day 18 and 30 ewes.On day 39 post-transfer,pregnancy rates remained 60% for day 6 ewes,33% for day 9 ewes,and 0% for day 12,18,and 30 ewes.The P4 treatment did extend the window of uterine receptivity to early embryos in ewes by one day,but did not create a universal recipient.Available results support the idea that a window of uterine receptivity to the conceptus exists in sheep that is independent of pregnancy recognition signaling.     

Effects of cortisol on pregnancy rate and corpus luteum function in heifers: an in vivo study

To determine whether glucocorticoids affect the function of the bovine corpus luteum (CL) during the estrous cycle and early pregnancy, we examined the effects of exogenous cortisol or reduced endogenous cortisol on the secretion of progesterone (P4) and on pregnancy rate. In preliminary experiments, doses of cortisol and metyrapone (an inhibitor of cortisol synthesis) were established (n=33). Cortisol in effective doses of 10 mg blocked tumor necrosis factor-induced prostaglandin F(2α) secretion as measured by its metabolite (PGFM) concentrations in the blood. Metyrapone in effective doses of 500 mg increased the P4 concentration. Thus, both reagents were then intravaginally applied in the chosen doses daily from Day 15 to 18 after estrus (Day 0) in noninseminated heifers (n=18) or after artificial insemination (n=36). Pregnancy was confirmed by transrectal ultrasonography between Days 28-30 after insemination. Plasma concentrations of P4 were lower in cortisol-treated heifers than in control heifers on Days 17 and 18 of the estrous cycle (P<0.05). However, the interestrus intervals were not different between control and cortisol-treated animals (P>0.05). Moreover, metyrapone increased P4 and prolonged the CL lifespan in comparison to control animals (P<0.05). Interestingly, in inseminated heifers, cortisol increased the pregnancy rate (75%) compared with control animals (58%), whereas metyrapone reduced the pregnancy rate to 16.7% (P<0.05). The overall results suggest that cortisol, depending on the physiological status of heifers (pregnant vs. nonpregnant), modulates CL function by influencing P4 secretion. Cortisol may have a positive influence on CL function during early pregnancy, leading to support of embryo implantation and resulting in higher rates of pregnancy in heifers.     

自然发情黄牛作奶牛胚胎移植受体可行性分析

在奶牛胚胎移植黄牛试验中，选用自然发情母牛作受体，移植鲜胚的受胎率为５７．１％（ｎ＝２１）。相反，用同期发情处理的母牛作受体，移植群胚的受胎率只有２６．１％（ｎ＝２３）。农区各人工授精站每天都有数头自然发情黄牛登门配种，因此认为，应用奶牛胚胎称植黄牛时，选择自然发情的作受体，既可提高移植成功率，又能省去同期发情处理费用，是今后在奶牛胚胎移植实践中，值得推广的一项措施。     

利用西杂牛和秦川牛做受体进行奶牛胚胎移植的对比试验

[目的]为了选择奶牛胚胎移植的理想受体。[方法]通过利用不同品种的本地黄牛～西杂牛84头和秦川牛77头做受体,进行荷斯坦奶牛胚胎移植效果的对比试验。[结果]西杂牛的同期发情率、受体可用率、受胎率都显著高于秦川牛（P〈0．05）,而且难产率低,奶水充足。[结论]表明西杂牛是奶牛胚胎移植的理想受体。     

不同胚胎移植方法对天祝白牦牛受胎率的影响

为提高胚胎移植技术在牦牛上的运用效果,选用51头甘肃省天祝县健康黑牦牛作为受体,以纯种天祝白牦牛作为供体生产胚胎,分别对同期发情处理和自然发情的受体牛进行鲜胚和冻胚移植试验。结果,同期发情处理的受体牛鲜胚移植的受胎率显著高于冻胚移植的受胎率(P0.05),分别为52%和38.5%;在自然发情受体牛的胚胎移植中也得到了相似结果,鲜胚和冻胚的移植受胎率分别为60%和50%,同期发情处理牛的平均妊娠率则低于自然发情受体牛的平均妊娠率(P0.05),二者分别为47.5%和54.5%。结论,牦牛鲜胚移植的受胎率明显高于冻胚移植的受胎率,而且自然发情受体牛的受胎率高于同期发情处理牛。