Equine embryo transfer: the effect of semen processing and donor mare management on recovery rates

• Author(s): Correia, Sónia Cristina Gonçalves
• Date: 2016
• Persistent ID: http://hdl.handle.net/10400.26/17021
• Origin: Escola Universitária Vasco da Gama
• Subject(s): Artificial insemination; Embryo transfer; Equine; Month; Pregnancy; Semen
• Document Type: Master thesis
• Language: English
• Advisor(s): Duarte, Sofia Alexandra Giestas Cancela; Pereira, Rosa Maria Lino Neto
• Contributor(s): Repositório Comum

Description

Embryo transfer (ET) is a biotechnology that allows to get more than one foal from a single mare during a breading season and also to prevent the removal of mares from their competition careers. Nevertheless, to achieve a successful outcome, the association of many factors must be considered such as the management of donor and recipient mares, the stallions and the veterinarian´s experience. The aims of this study were to evaluate (1) if some of characteristics related to the donor mares such as the breed and the reproductive status, may influence the embryo recovery; (2) if climate and different donor mares location may have impact in breeding programs; (3) the effect of some reproductive techniques and embryo transfer methodologies such as the day of uterine flushing, the type of semen, the stallion and the moment of inseminations and transfer as potential effectors of success. To achieve the objectives pointed out, one hundred and fifty six uterine flushes and eighty eight embryo transfers were performed. Obtained results showed higher embryo recovery rates at day 8 (61.1%) and an overall pregnancy rate of 62.2%. An influence of the month of the year (P=0.04) and of the type of semen (fresh or frozen; P=0.03) on the number of positive embryo collections were identified. No other significant effects upon the remaining determinants under testing were observed, although stallions were responsible for inducing 11% of the variability within embryo recovery rates. In conclusion, the main factors that had a great influence in this embryo transfer program were the type of semen and the day and month of the uterine flushing procedure. The use of fresh semen for donor mares insemination and recovery at day 8 increased the number of embryos that were collected during this period, although lower results were obtained in July-August. These procedures should be consider and implement in mare embryo transfer centres.