牛胚胎快速冷冻技术的研究

我们对牛胚胎快速冷冻技术进行了研究。１９９２年８月一１１月间在木兰县，共移植受体母牛９９头，有４６头受体母牛妊娠，妊娠率为４６．５％，有２９头受体牛产犊，产犊率为２９．３％。通过研究得知，牛胚胎快速冷冻技术可以应用于生产。     

安格斯牛冻胚洲际间引种试验成功

我们从澳大利亚引入安格斯（Ａｎｇｕｓ）牛７日龄冻胚１６枚。这１６枚冷冻胚胎在液氮中保存８９４天后，用３６℃水浴解冻（２５秒钟），全部回收，在室温２７℃条件下，用１０％蔗糖一步脱除抗冻剂（甘油）１０分钟后，移入２００％犊牛血清ＰＢＳ１０分钟，再移入同样浓度的犊牛血清ＰＢＳ中１０分钟。按常规形态鉴定方法，对胚胎评级，１０枚为可用胚胎，解冻后胚胎可用率为６２．５％（１０／１６。将１０枚可用胚胎用非手术法，移入发情周期与胚胎发育期同步的５头受体牛，结果２头妊娠，移位妊娠率为４０％（２／５）。妊娠足月后，２头受体牛各产公犊１头。在我国首次获得成功。     

胚胎移植受体黄牛的试验研究

试验期内共选择受体黄牛５９头，冻胚移植３３头，选择移植率达５５．５％，妊娠１１头，移植受胎率达３３．３％，分娩９头，妊娠产犊率达８１．８％，经过选牛实足和资料整理，从中得出几项有价值的数据。     

应用广西黄牛作受体进行奶牛胚胎移植的研究

本试验通过超排11头荷斯坦牛,获得42枚可用胚胎,分别移植到19头广西本地黄牛和18头低产奶牛中,广西黄牛受体的妊娠率为36.81%,其中母犊5头,公犊2头。荷斯坦牛受体的妊娠率为44.44%,流产2头,流产率25%,产犊6头,公母各3头。黄牛受体与荷斯坦牛受体生下的荷斯坦胚胎牛初生重差别明显,但经培育后,体重差距逐步缩小;产奶性能无差别。广西本土黄牛可以用于荷斯坦牛胚胎移植的受体牛,加强饲养管理可获得好的受胎率;做好胚胎移植出生犊牛培育,可获得良好的经济效益。     

牛人工授精后血清中孕酮浓度的变化与受胎效果

笔者通过对授精当天、７天后和２０～２２日后牛体血清中孕酮浓度的测定（酶免疫法）与分析，探讨了该法应用于牛的发情鉴定和早期妊娠诊断的可能性。在５２头供试牛中，有４７头（９０．４％）属正常发情（排卵性发情），有１头（１．９％）属假发情（不排卵性发情），另有４头（７．７％）未发情，６０天后妊检结果，有３６头（６９．２％）怀孕，这３６头牛均为正常发情者。输精后第７天血清中的孕酮浓度，妊娠牛（ｎ＝３６）与非妊娠牛群（ｎ＝１６）间无显著差异，但在第２０～２２天后的第二次发情预计日，妊娠牛的孕酮浓度［５．３±１．７（１．２－８．２）ｎｇ／ｍｌ］则显著高于非妊娠牛［１．３±１．２（０．４－５．５）ｎｇ／ｍｌ］。采用此时血清中孕酮浓度指标，判定有４０头牛妊娠，其早期妊娠诊断的准确率在妊娠牛为９０．０％（３６／４０），对非妊娠牛达１００％（１２／１２）。因而，本法在早期妊娠诊断上具有实用价值。     

奶牛产双头犊引起难产一例

奶·牛·产·双·头·犊·引·起·难·产·一·例○北京市西郊农场奶牛公司（１０００９４）张忠德在奶牛难产中，胎儿性难产是由于胎儿过大、姿势不正及胎儿畸形引起的。笔者最近遇到１例双头犊引起的难产，临床上少见。９２０７７号母牛，１９９２年７月２０日出生，体...     

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。     

胚胎移植受体黄牛的试验报告

试验期内共选择受体黄牛５９头，冻胚移植３３头，选择移植率为５５．９％；妊娠１１头，移植妊娠率为３３．３％；分娩９头，妊娠产犊率为８１．８％，试验结果达到预期的目的。     

牛性控体外受精冷冻胚胎移植试验

从美国引进的荷斯坦牛性控体外受精冷冻胚胎95枚,以鲁西黄牛、南阳牛、西杂牛、荷斯坦牛为受体进行移植试验.结果显示,移植受体95头,妊娠44头,妊娠率46.3%,流产7头,产母犊37头,效果良好.     

奶牛分割胚胎移植黄牛效果观察

用便携式分割仪在现场分割7日龄鲜胚。二枚半胚成对移植给172头黄牛受体．受体移植妊娠率50％(86／172），现已有68头受体产犊91头．其中23对为同卵双胎．双胎率33．8％(23／68)。对分割胚胎的移植妊娠率产犊率、妊娠期、季节、黄体状况等多种因素进行了研究和比较，结果表明差异皆不显著。     

奶牛胚胎分割试验研究

简单分割7～8天奶牛胚胎59枚(117个半胚)。裸半胚成对移给59头奶牛或黄牛,80～90天有27头(45.8％)妊娠。最后24头受体产犊34头,半胚产犊率29.1％(34/117)。有10对双胎,双胎率41.7％(10/24)。比较在不同情况下—7天或8天;晚桑椹或囊胚期;透明带软化处理或不软化处理—分割的半胚,成对移植后受体妊娠率分别是40.0％和57.9％;35.7％和54.8％;48.6％和41.7％。半胚产犊率分别是26.6％和34.2％;23.6％和33.9％;30.0％和27.7％。均无显著差异(P>0.05)。分割优质胚胎得到最好的(35.7％)半胚产犊率。半胚在体外5小时内移植有较高(30.5％)的产犊率。试验探索了奶牛半胚移给远处分散的农户黄牛的可能性。11对奶牛半胚移给11头黄牛有6头(54.5％)妊娠。最后5头受体产下7头奶牛犊,两对同卵双胎。     

Birth of live calves by in vitro embryo production of slaughtered cows in a commercial herd in South Africa

In vitro fertilisation (IVF) has become a useful breeding tool in most of the developed world. In this paper the success of bovine IVF and the birth of live calves under typical South African conditions is reported. Oocytes for IVF were collected from the ovaries of 6 slaughtered Bovelder beef cows. On average, 36.2 oocytes per donor were retrieved. From these oocytes, 43 blastocysts were produced from 5 of the donors by IVF with frozen Bovelder semen. The best 11 of these embryos were transferred into oestrous, synchronised Bovelder recipients in the same herd. As a result, 7 calves were born (a 64% calving rate) from 4 of the original donors. The calves had a normal birth mass, but the mean gestation length of the male calves was significantly longer than the herd average (291.6 versus 285.2 days respectively). No calving difficulties were encountered. In summary, it was shown that IVF for bovine embryo production and transfer is possible on a commercial basis in South Africa.     

Mixed-breed twin production by contralateral direct-transfer of male embryos to beef cow recipients bred to GnRH-based, fixed-time AI

Two experiments were conducted to develop protocols for the use of fixed-time artificial insemination and embryo transfer (TAI and TET, respectively) to increase beef cattle productivity. Suckled beef cows were given GnRH (100 µg im) on Day − 10, and PGF (25 mg im) on Day − 3, with TAI on Day 0 (66 h later), and assigned to either embryo recipient (ER) or no embryo (NR) treatments on Days 6 or 7. Semen from Gelbvieh (GB) beef sires was used for TAI; sexed-male in vivo developed Holstein embryos (HO) were placed nonsurgically (TET) into the uterine horn contralateral to the corpus luteum. In Experiment 1, ovarian status of cows (n = 111; 69 ± 11 d postpartum; mean ± SD on Day 0) in Groups I and II was presynchronized with a single PGF treatment on Day − 24; Groups II and III received GnRH concurrent with TAI, and ER (n = 78) were selected from all groups on Days 6 or 7. Neither presynchronization nor GnRH affected rates of recipient selection, Day 45 pregnancy (43.2, 43.2, and 54.0% for Groups I, II and III, respectively), or calving (40.5, 37.8, and 43.2%). However, treatment with GnRH increased HO-birth rate (8.0, 14.0 and 24.0%; P < 0.05). In Experiment 2, cows (n = 99, 113 ± 10 d postpartum) were assigned on Day 7 to NR and ER, with and without hCG (2500 IU im), following a TAI protocol (as per Group III in Experiment 1). Treatment with hCG increased reproductive rate (1.16 vs 1.44 calves/calving; P < 0.05), but had no significant effect on rates of Day 45 pregnancy (45.3 vs 41.3%), calving (31.2 vs 37.0%) or HO-births (20.0 vs 26.0%). In summary, GnRH-based synchronization rates were 71.2% (based on circulating progesterone concentrations that were < 1.0 ng/mL on Day 0 and ≥ 1.0 ng/mL on Day 7); TET did not affect GB-birth rate, but more calves were produced by ER than NR cows (1.43 vs 1.02 calves/calving; P < 0.01); and weaned calf production was 53% greater for twin- than singleton-suckled cows (392 ± 25 vs 256 ± 11 kg/dam; mean ± SEM, P < 0.05). Therefore, GnRH-based TAI and TET protocols for mixed-breed twin production increased beef cow productivity.     

饲料营养对母牛繁殖率影响效果研究

通过对妊娠后期（后１４２ｄ）母牛、带犊哺乳母牛的不同阶段饲料营养配合试验,探讨母牛的饲养技术方案。选择条件大致相同的妊娠后期母牛３６头,随机分为试验１、２组和对照组各１２头。试验１组和试验２组根据妊娠月份及粗饲料种类不同,粗饲料日喂量各有所调整,对照组牛则采用当地的传统饲养方式。试验结果,试验１组母牛产仔成活１１头,哺乳期平均１１７ｄ,断奶成活１０头,繁殖成活率８３．３％,母牛产后开始发情时间平均     

Bovine embryo transfer pregnancies. I. Abortion rates and characteristics of calves

Data were obtained from 1,908 pregnancies resulting from bovine embryo transfer procedures. Responses examined included sex ratio, fetal, neonatal and preweaning death losses, birth weight and calving assistance. The sex ratio for 1,751 embryo transfer calves examined was 51.11% males. Cows older than 10 yr that had become repeat breeders produced more (P less than .05) male calves than other donors. Breed of embryo, age and quality of embryos at the time of transfer, embryo storage time from collection to transfer, asynchrony of recipient with donor estrus and number of palpable corpora lutea in superovulated donors were not related to sex ratio (P greater than .05). The abortion rate between 2 and 3 mo of gestation in embryo transfer recipients was 3.15%, and between 3 to 7 mo, 2.14%. Neonatal and preweaning losses for 1,682 calves with complete information were 1) congenital defects, .54%; 2) death due to premature birth (7 to 8 mo of gestation), .18%; 3) dystocia-related deaths, 2.38%; 4) deaths of unknown causes at birth, 2.14%; 5) deaths of unknown causes from 24 h after birth to weaning, 1.43%; 6) deaths due to calfhood diseases, 1.25% and 7) deaths due to environmental factors, 1.13%. Total losses of 2-mo pregnancies due to abortion or death of calves or recipients were 14%. Birth weight of embryo transfer calves changed .29 kg/d of deviation from average gestation length (P less than .005) for pregnancies within breeds. Birth weight was also affected (P less than .005) by donor breed and recipient breed and age. Male calves averaged 2.19 kg heavier (P less than .005) than females. Calving assistance was affected by donor breed; Angus calves required the least assistance (P less than .005). Hereford, Holstein and Limousin calves were similar and intermediate; Simmental calves needed the most calving assistance. Recipient breed and age influenced calving ease, with younger recipients of Angus and Hereford descent requiring more assistance (average calving score, 2.1) than both cow (1.3) and heifer (1.5) recipients of the larger Continental European breeds. Characteristics of 305 non-embryo transfer calves were not significantly different from 185 embryo transfer calves from the same farms. We conclude that embryo transfer calves did not differ from the non-embryo transfer population in any of the characteristics studied.     

Bovine OPU‐Derived Oocytes can be Matured In Vitro for 16–28 h with Similar Developmental Capacity

The aim of this study was to determine the optimal maturation culture period of ovum pick up (OPU)‐derived cumulus oocytes complexes (COCs) in relation to their developmental capacity. Embryo production, embryo cryotolerance, post‐transfer embryonic survival and calf characteristics such as gestation length, birthweight and sex ratio were investigated. This retrospective study covers the analyses of ovum pick up –in vitro production and calving results from a commercial programme that took place between March 1994 and September 2004. Donors were both heifers (of which approximately 90% pregnant) and cows (of which approximately 10% pregnant). Embryo production analyses were based on 7800 OPU sessions conducted from January 1995 until January 1999. Analyses of calving rate were based on 13 468 embryo transfers performed during January 1995 until May 2002. Analyses on calf characteristics were based on 2162 calves born between March 1994 and September 2004. The in vitro maturation culture period ranged from 16 to 28 h. The mean production rate of transferable embryos was 16.5% (1.2 embryos per OPU session). Length of maturation culture period did not affect the production of transferable embryos. Mean calving rate was 40.9% and 38.7% for fresh and frozen/thawed embryos, respectively. Calving rate was not affected by the maturation culture period. Mean birthweight, gestation length and proportion of male calves were 46 kg, 281.9 days and 52.8%, respectively. Maturation culture period did not affect these variables. In conclusion, this study shows that the in vitro maturation culture period within the range of 16–28 h does not affect in vitro embryo production, embryo cryotolerance, post‐transfer embryonic survival and calf characteristics, suggesting that all COC batches collected by OPU on the same day, can be fertilized in one IVF session without a significant loss in the production from oocyte to calf.     

Relationship between stress levels of the antepartum cow and her newborn calf

We investigated the relationship of the stress levels of the dam before and after delivery to that of her offspring soon after birth. Eight pregnant cows were penned 7 days before calving. Blood was taken from the jugular vein of cows at ?7, 1, 2 and 3 days from calving. Blood was also taken from newborn calves at 6 h and 1 and 2 days after birth. Concentrations of cortisol and immunoglobulin G in blood and colostrum were examined. Pearson's correlation coefficient showed that the higher the plasma cortisol concentration of a cow before calving, the higher that of its calf after birth (all P < 0.01). In addition, path analysis demonstrated that the direct effect of the plasma cortisol concentration of the dam before calving on the plasma cortisol concentration of her calf after birth was 0.971 (P < 0.01). However, the colostrum cortisol concentration correlated with neither plasma cortisol concentrations of cows before calving nor that of calves after birth. Unlike cortisol, a clear correlation of immunoglobulin G concentrations in plasma and colostrum was not observed between cows and calves. The results indicate stress is transferred from a cow to her newborn calf not by way of the colostrum but through the placenta.     

The transfer of fresh and frozen embryos in an elite swamp buffalo herd

To investigate the development of fresh and frozen swamp buffalo embryos after transfer to synchronized recipients, 14 fresh embryos and 28 frozen embryos, collected from Thai swamp buffalo cows of an elite herd at the Surin Breeding Center, were transferred nonsurgically to 31 synchronized recipients buffalo cows. One fresh embryo was transferred to each of 14 recipients. Twenty eight frozen embryos were transferred to 17 recipients of which 7 cows received I embryo, 9 cows received 2 embryos and 1 cow received 3 embryos. Pregnancy was diagnosed by real time B-mode ultrasonography one month after transfer and confirmed by rectal palpation one and two months later. The pregnant cows were kept under observation until calving. The results of fresh embryo transfer showed that 5/14 (35.7%) were pregnant after 30 days, 4/14 (28.6%) remained pregnant until the 3rd month and 2/14 (14.3%) calved. With the frozen embryos, only one cow which received three embryos became pregnant and remained so for 3 months although the embryo did not survive to full term. The overall pregnancy rate using frozen embryos was 5.9% (1/17). The study demonstrated the possibility of performing embryo transfer in elite buffalo herds for genetic improvement, however the use of frozen embryos needed further investigation.     

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)。