Influence of Intrauterine Fluid Detection, Number of Transfers and Age of the Recipient on Pregnancy Rate and Early Embryonic Loss in a Commercial Embryo Transfer Program

A novel method for equine embryo transfer from contaminated recipient mares into second healthy recipients for surviving embryos

Embryo transfer (ET) is regarded as one of the reproductive methods for genetic improvement initiatives in the horse business. The current study aimed to increase the success rate of ET by re-flushing and re-transferring of embryos from contaminated recipient mares into second healthy recipients. The study involved 25 recipient mares that demonstrated embryonic vesicles inside intraluminal fluid (ILF) on ultrasound scanning 2 ± 0.5 days after ET. Seven recipient mares were left without re-flushing and re-transferring of embryos (control group) and 18 recipient mares (treated group) were subjected to re-flushing and re-transferring of the embryos to second healthy and prepared recipients. The retrieved fluid from treated mares was subjected to microbiological and cytological examinations. The results revealed mixed and single infections, as well as polymorphonuclear neutrophils (PMNs). The total bacterial count and cytology findings revealed that all first recipient mares had endometritis. All control mares showed embryonic death at 14 ± 1.1 days (13-15 days) of embryonic age. In treated group, microscopic evaluation of retrieved embryos revealed a well-developed thick capsule in 12/18 (66.7 %) of them and a normal capsule in 6/18 (33.3 %). The pregnancy rate in well-developed capsule embryos was greater (66.7 %) than in typical capsule embryos (33.3 %). This study illustrates the value of swabbing the uterus of the recipient mares during estrus prior to ET and their checking at 2 days after ET. In addition to boosting pregnancy rates in ET commercial programs, our novel method can protect the embryos from the harmful effects of the inflammatory process and help them survive.

Factors affecting the efficiency of equine embryo transfer (EET) in polo mares under subtropical conditions of Pakistan

Equine embryo transfer (EET) is a prominent technology in the equine breeding industry, and its efficacy is affected by a number of factors. The current study aimed to determine the effects of the breed of donor/recipient mares, estrus/ovulation induction treatment, cooled transportation of embryos, and synchrony between donor and recipient mares on the efficiency of the EET under subtropical conditions of Pakistan. A total of eighty-four (n = 84) Polo-playing donor mares (Argentino-polo = 41 and Anglo-Arab = 43) and seventy (n = 70) recipient mares (light breed = 26 and heavy breed = 44) were used for EET. The donor mares exhibiting natural estrus (n = 28) were detected by teaser a stallion, and corpus luteum (CL) having mares (n = 56) were treated with prostaglandin (150 μg of Cloprostenol) for estrus induction. The mares' follicular growth was monitored through ultrasonography until the dominant follicle's size reached 35 mm or more with a moderate to obvious uterine edema score. Afterward, the mares were treated either with GnRH, i.e., 50 μg of Lecirelin acetate (n = 41) or Ovusyn, i.e., 1500 IU hCG (n = 43). Insemination with chilled semen was performed 24 hours later. The embryos were collected non-surgically, 7 or 8 days after ovulation, from the donor mares. The collected embryos were transferred into the well-synchronized recipient mares as fresh (n = 44) or chilled (n = 26) embryos. The pregnancy after ET was checked through ultrasonography. Statistical analysis revealed that the embryo recovery rate (ERR) remained significantly higher (P<0.05) for the Prostaglandin (PG) treated group of donors as compared to the natural heat group of donors. The breed of donor mares, type of ovulatory treatment given, and day of embryo collection did not significantly (P>0.05) affect the ERR. There was no significant effect of the type (fresh vs chilled), classification, and stage of development of embryo on pregnancy outcomes (P>0.05). ET pregnancy rate was significantly affected by the breed of recipient mares and ovulation synchrony between donor and recipient mares (P<0.05). In conclusion, under the subtropical conditions of Pakistan, PG-based estrus induction of donor mares, breed of recipient mares, and ovulation synchrony between the donor and recipient mares had a substantial effect on the efficiency of EET.