Open Access
Research (Published online: 15-11-2019)
13. Pregnancy rates in hair sheep after Ovsynch synchronization and a combined intracervical fixed-time artificial insemination and 10-day mating period
D. A. Vallejo, J. D. Londoño, Y. A. Yepes, V. Tamayo, A. F. Mejia and J. G. Maldonado
Veterinary World, 12(11): 1779-1783

D. A. Vallejo: Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
J. D. Londoño: National Learning Service – SENA, Center of Renewable Natural Resources – La Salada, Research Group La Salada, Colombia Government, Caldas, Colombia.
Y. A. Yepes: Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
V. Tamayo: Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
A. F. Mejia: Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
J. G. Maldonado: Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.

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

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Article history: 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

Citation: 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.
Abstract

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.