The present study carried a meta-analysis of the pregnancy rates of different synchronization protocols implemented in ewes in Turkey. A common pregnancy rate was estimated by coalescing pregnancy rates, and the heterogeneity between the studies was explored. All studies were carried out independently. This article compiled 28 studies that determined the pregnancy rate for 2,437 ewes in the synchronization studies between the years 1995-2020. The overall effect size of the meta-analysis was

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... d to be 0.66 (95% confidence interval; 0.58-0.74) (p<0.001). This meta-analysis indicates that fertility parameters were improved with the highest effect size in the synchronization protocol used in ewes during the breeding season by combining various doses of PMSG at the end of intravaginal sponge application as a source of progesterone. In terms of subgroups, 40 mg FGA + 300 IU PMSG (95% confidence interval; 0.50-0.61), 40 mg FGA + 500 IU PMSG (95% confidence interval; 0.44-0.52), and 40 mg FGA + 700 IU PMSG (95% confidence interval; 0.41-0.61) protocol effect size was estimated to be higher than other protocols during the season. Thus, it is possible to control the reproductive performance in enterprises with estrus synchronization protocols and mating of ewes. However, it is important to validate which of these methods are optimum in terms of economy and efficiency in enterprise conditions. Considering the effects of synchronization protocols on pregnancy, it is predicted that Bayes meta-analysis will guide enterprises as a decision support system in achieving optimum pregnancy rates.