The efficacy of the Ovsynch program in improving conception and pregnancy rates was compared with untreated controls and other synchrony programs in lactating dairy cows. This meta-analysis examined 71 treatment and control comparisons extracted from 53 research papers. Programs evaluated included Ovsynch, natural breeding, single, double, or triple prostaglandin injections, Select Synch, Heat Synch, and modified Ovsynch.
Pregnancy rates for Ovsynch programs did not differ significantly from those with natural breeding programs [predicted Bayesian relative risk (RR) = 1.04, 95% Bayesian credible interval = 0.36 to 3.23]. Results of Ovsynch vs. PGF 2Ξ± programs showed that the risk of conception (predicted Bayesian RR = 0.89, 95% Bayesian credible interval = 0.31 to 2.64), and pregnancy rates predicted Bayesian RR = 1.11, 95% Bayesian credible interval = 0.61 to 2.13) did not differ significantly between the Ovsynch group and cows in the PGF 2Ξ± group. Comparisons between Ovsynch and Select Synch demonstrated that the risk of conception (predicted Bayesian RR = 0.94, 95% Bayesian credible interval = 0.52 to 1.59), and pregnancy rates (predicted Bayesian RR = 1.08, 95% Bayesian credible interval = 0.38 to 3.09) did not differ significantly between the 2 groups. Examination of Ovsynch vs. modified Ovsynch programs showed that the risk of pregnancy in cows synchronized with modified Ovsynch was similar to those treated with Ovsynch (predicted Bayesian RR = 0.89, 95% Bayesian credible interval = 0.71 to 1.12).
Meta-analyses identified that the conception and pregnancy rates obtained with the prostaglandin, Select Synch, and modified Ovsynch (including presynch and CoSynch) programs were comparable with the Ovsynch program. Modifications to the Ovsynch program such as presynchronization and timed artificial insemi-