Embryo transfer technology in animals: An overview

TURKISH JOURNAL OF VETERINARY AND ANIMAL SCIENCES, 2014

The objective of this study was to investigate the conception rates achieved with the transfer of in-vivo-derived sexed and unsexed Holstein bovine embryos to appropriate recipients and to determine the accuracy of nonelectrophoretic PCR sexing. Sevenday-old embryos were derived in vivo by the nonsurgical flushing of the uterus. Before being vitrified and frozen some of the embryos obtained were sexed, while others were not sexed and were maintained as the control group. After thawing, the sexed and unsexed embryos were transferred to 23 and 21 bovine recipients, respectively. The conception rates achieved with the transfer of the sexed and unsexed embryos were 30.4% (7/23) and 42.9% (9/21), respectively. The difference between conception rates achieved in the 2 groups was not statistically significant (P > 0.05). For the sexed embryos the conception rates achieved with the transfer of male and female embryos were 27.2% (3/11) and 33.3% (4/12), respectively. The accuracy of embryo sexing with nonelectrophoretic PCR was 66.6% for male embryos and 100% for female embryos postdelivery. The mean rate of accuracy determined for embryo sexing at the end of the study was 83.33%.

International Journal of Sciences: Basic and Applied Research, 2020

The purpose of this research to find out the morphological differences of fresh and frozen embryos which is produced in vitro and the success rate of pregnancy embryo transfer in Bali cattle. The method used in embryos produced were oocyte collection, in vitro maturation, in vitro fertilization, in vitro culture, there are two embryos produced, fresh embryos and frozen embryos. Embryos that have been produced in vitro will be transferred to the recipient Bali cattle that have been estrus synchronized. Results revealed that morphology of fresh embryos have symmetrical shapes whereas frozen embryos shrink, then the pregnancy rate was higher in the used of fresh embryos (41%), compared to the used of frozen embryos (12,5%).

Reproduction in Domestic Animals, 2008

Embryo transfer has been an inherent part of cattle breeding for more than 35 years and has also gained remarkable interest from the equine industry after several breeds allowed registration of more than one foal per year. In both large animal species, non-surgical embryo recovery and transfer are wellestablished techniques. However, success rates after superovulation and cryopreservation of embryos in horses are still lagging behind those of cattle, and more research is needed to address these areas. To address the problem of freezing large equine embryos, we offer a preliminary demonstration of a new cryopreservation method which involves reduction of the blastocoelic volume and microinjection of cryopreservative. Successful cryopreservation will improve the ability of practitioners to preserve and implant embryos in recipient mares. Recent advances in the use of equine FSH to induce superovulation in mares brings to the forefront the issue of how to best preserve the large number of embryos that are produced. Finally, the use of sexed semen after superovulation will provide the bovine and equine breeding industry the offspring of the desired sex.

Reproduction Nutrition Development, 1998

This paper reviews the status of embryo transfer and the major technologies applied to preimplantation of embryos in sheep. Embryo production from superovulated ewes is hindered by an unpredictable response to hormonal treatment. Progress in this area should be expected by an appropriated control of follicular development with gonadotropin-releasing hormone (GnRH) agonist or antagonist prior to gonadotrophin administration. Simple protocols for the cryopreservation of sheep embryos by vitrification are already available and the development of frozen-thawed blastocysts to term is close to the fresh ones. Further research is required to identify factors able to promote the maturation in vitro of oocytes, namely those obtained from prepubertal animals. Semen and embryo sexing procedures are available in cattle although much less attention was paid to their application to sheep. Among all the reproductive technologies, cloning with embryonic and foetal cells has progressed dramatically in sheep and nuclear transfer has been used to produce transgenic animals as an alternative to pronuclear injection. The production of the first lamb cloned from a somatic cell opened new opportunities in animal breeding as well as exciting lines of basic research. The overall conclusions are that, apart from superovulation, the application of in vitro technologies is likely to evolve rapidly and once applied, a great impact on traditional and new animal productions should be expected. However, a better understanding of the changes in gene expression, induced in embryos by different in vitro manipulation procedures, is necessary to prevent abnormal foetal development. © Inra Elsevier, Paris. superovulation / in vitro maturation / embryo freezing / nuclear transfer / transgenesis / sheep Résumé ― Transfert d'embryons et techniques associées en reproduction ovine. Cette revue traite du transfert d'embryons et des principales biotechnologies appliquées à l'embryon ovin. La production d'embryons, après superovulation, est limitée par la réponse non reproductible au traitement hormonal. Un progrès pourrait venir d'un contrôle approprié du développement folliculaire

Reproduction Fertility and Development

The objective of this study was to analyze factors affecting the pregnancy rates after transfer of IVF-derived Japanese Black embryos. Holstein cows and heifers (n = 7250) were selected as recipients, and embryo transfers were performed for 3 yr (between 1998 and 2000). The IVM-IVF procedure was performed according to a method previously described (Hamano S and Kuwayama M 1993 Theriogenology 39, 703-712). IVF-derived embryos that developed into expanded blastocysts (grade 1, manual of IETS) after 7 to 8 days (insemination = Day 0) were used for this study. Some of these embryos were frozen in TCM-199 supplemented with 1.4 M glycerol, 20% calf serum, and 0.25 M sucrose. The embryos were seeded at −6 • C, held at −6 • C for 10 min, and then cooled to −25 • C at a rate of 0.33 • C min −1. Frozen embryos were thawed in a 30 to 35 • C water bath after 10 s of air thawing. Fresh (n = 3952) or frozen-thawed (n = 3298) embryos were nonsurgically transferred to recipients on Days 6 to 9 of the estrous cycle. Data collected at the time of embryo transfer included recipient parity (cow or heifer), whether recipient estrus was natural or synchronized with PGF 2α , cloprostenol or CIDR, methods of estrous confirmation (showing standing heat, rectal palpation of ovary without standing heat, or showing only mucous vulvular discharge), number of examinations of the CL by palpation per rectum (twice on the day before embryo transfer and the day of embryo transfer, or once on the day of embryo transfer), type of embryos (fresh or frozen), and day of the estrous cycle at the time of embryo transfer. CATMOD procedures of SAS were used to determine the factors affecting the pregnancy rate. Overall pregnancy rates were 37.3% (n = 2704). Whether recipient estrus was natural or synchronized and the type of embryos did not influence the pregnancy rates. Heifers had significantly higher pregnancy rates than cows (44.0% v. 33.0%, respectively, P < 0.05). Pregnancy rates among the subset of heifers and cows showing standing heat were significantly higher than those showing only mucous vulvular discharge (39.5% v. 33.5%, respectively, P < 0.05). Examining the CL twive had a significantly higher pregnancy rate than did a single examination of the CL (41.1% v. 35.6%, respectively, P < 0.05). Pregnancy rate on Day 8 (38.4%, 1358/3533) of the estrous cycle at the time of embryo transfer was significantly higher than on Days 6 (27.7%, 23/83) and 7 (36.2%, 1235/3408) (P < 0.05), and the pregnancy rate on Day 6 of the estrous cycle at the time of embryo transfer tended to be lower than on Day 9 (38.9%, 88/226) (P < 0.08). These results demonstrate that confirming standing heat, performing CL examination twice before embryo transfer, freezing high quality embryos, and performing embryo transfers on Day 8 resulted in an improved pregnancy rate for the transfer of IVF-derived embryos.

Animal Frontiers, 2013

Tropical Animal Health and Production, 2010

The objective of this study was to determine if the technique of embryo transfer in cattle can be commercially feasible in a region situated in the humid tropics of Mexico. Twenty-six Bos taurus and twenty-six Bos indicus cows were estrous synchronized and superovulated to obtain a total of 80 embryos of both sub-species. Embryos were classified using stereoscopic microscopy based on established criteria. Nine dual-purpose farms situated in the tropics of Mexico were chosen to provide ten recipient cows each to transfer one embryo per cow. The females were transferred using a fixed-time protocol after verifying the presence of a corpus luteum on the seventh day after the end of hormonal treatment. Pregnancy diagnosis was carried out 28 days after embryo transfer by ultrasonography. Estimation of the cost was determined by calculating the expenses for preparation of the donor and embryo recovery, which were US $633 and US $589 for B. taurus and B. indicus, respectively. The cost of each embryo was determined considering the number of transferable embryos recovered, which was 3.8 on mean. The cost of each conception was calculated taking into account the percentage of pregnant animals (27% on mean), and the cost for preparing donor and recipient cows, for transferring embryo. The overall cost per gestation was US $1,447. Considering a 50:50 ratio of male to female born, the cost for a replacement heifer calf was US $2,894, which surpassed by far the commercial cost of a crossbred ready-to-bred heifer normally used as replacement (approximately US $900).

2003

Journal of Equine Veterinary Science, 2013

Embryo transfer Mare Embryo size Embryonic stage Embryo quality Synchrony of ovulation Brazilian jumper horse breed a b s t r a c t This study aimed to evaluate the effects of certain embryo transfer parameters on the pregnancy rate after equine embryo transfer of the Brazilian Jumper Horse breed. The size, embryonic development stage, embryo quality, and synchronization of ovulation between the donor (n ¼ 120) and recipient (n ¼ 420) were evaluated in 396 embryos. Embryo recovery was performed on Day 6-9 after ovulation (Day 0 ¼ day of ovulation). The recipient mares were chosen on the day of embryo recovery, and the transfers were performed that same day. The embryo size (diameter including envelopes; n ¼ 396) ranged from 150 to 3000 mm; 67.1% measured between 400 and 1199 mm. The embryo size (400-1199 mm vs. 399 mm); stage of development (n ¼ 396; blastocyst and expanded blastocyst versus compact morula and early blastocyst); quality (n ¼ 396; grade 1 [excellent]), 2 [good], or 3 [poor]); and synchronization of ovulation between the donor and recipient (0, 1, 2, 3, and 4 days versus À1, 5, and 6 days, respectively) all affected pregnancy rate (P < .05). The pregnancy rate did not differ significantly among transfers performed on Days 0, 1, 2, 3, and 4. In conclusion, embryos measuring 400-1199 mm produced higher pregnancy rates in recipients than embryos measuring 150-399 mm, and blastocysts and expanded blastocysts produced pregnancy more efficiently than morulae and early blastocysts. The embryo quality also affected the pregnancy rate. Synchronization of donor and recipient ovulation to Days 0-4 improved the efficiency of embryo transplant.

1987