Pregnancy rates in hair sheep after Ovsynch synchronization and a combined intracervical fixed-time artificial insemination and 10-day mating period

Vet World Vol.12 November-2019 Article-13

Research Article

Veterinary World, 12(11): 1779-1783

https://doi.org/10.14202/vetworld.2019.1779-1783

D. A. Vallejo¹, J. D. Londoño², Y. A. Yepes¹, V. Tamayo¹, A. F. Mejia¹, and J. G. Maldonado¹

1. Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
2. National Learning Service – SENA, Center of Renewable Natural Resources – La Salada, Research Group La Salada, Colombia Government, Caldas, Colombia.

Background and Aim: This study aimed to evaluate the pregnancy rates in hair ewes using an Ovsynch synchronization protocol under a breeding system that combines fixed-time insemination plus a 10-day mating period as an alternative.

Materials and Methods: Through an experimental study (n=27), ewes were randomly located into one of three treatments: (1) Pre-synch (n=9): Prostaglandin F2α (PGF2α)+Gonadotropin-releasing hormone (GnRH)+PGF2α+GnRH; (2) Ovsynch (n=9): GnRH+PGF2α+GnRH; and (3) control: Ewes bred by natural mating (NM) (n=9). Ewes were fixed-time inseminated (fixed-time artificial insemination [FTAI]) with fresh semen, collected just before the insemination time through vaginoscopy at 16 h after the second GnRH (gonadorelin) injection. Each experimental group was placed separately during 15 days and, after this time, fertile rams were allowed back with ewes for a 10-day mating period. Control group ewes remained with the rest of the herd suitable for breeding and were bred under NM. Pregnancy diagnosis was performed by ultrasound at 28-, 56-, and 84-day post-breeding to differentiate between FTAI and NM pregnancies. Total (FTAI±NM) pregnancy rates at 56-day post-breeding were used to compared Pre-synch, Ovsynch, and control. For this purpose, two-tailed proportions comparison z-test was used with a 95% confidence level, for testing as the null hypothesis whether two proportions were equal.

Results: Pregnancy rates were higher in control ewes (66.4%) than FTAI (46.6%). When pregnancy rates after a 10-day mating period (40%) were added, the final rate (86.6%) was significantly (p<0.05) higher in Ovsynch-based protocols. The pregnancy rate was significantly lower in FTAI ewes compared to FTAI +10-day mating group (p<0.05). The overall pregnancy rate was 88.0, 85.7, and 67.0 (p>0.05) for Pre-synch, Ovsynch, and control ewes, respectively.

Conclusion: These results provide evidence on the benefits of combined FTAI protocols for improving the reproductive efficiency of sheep. Keywords: ewes, fixed-time artificial insemination, Ovsynch, pre-synch.

Keywords: ewes, fixed-time artificial insemination, Ovsynch, pre-synch.

How to cite this article: Vallejo DA, Londoño JD, Yepes YA, Tamayo V, Mejia AF, Maldonado JG (2019) Pregnancy rates in hair sheep after Ovsynch synchronization and a combined intracervical fixed-time artificial insemination and 10-day mating period, Veterinary World, 12(11):1779-1783.

Received: 16-06-2019 Accepted: 20-09-2019 Published online: 15-11-2019

Corresponding author: D. A. Vallejo E-mail: dantonio.vallejo@udea.edu.co

DOI: 10.14202/vetworld.2019.1779-1783

Copyright: Vallejo, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.