Yudit Oktanella, Imam Mustofa, Suherni Susilowati, Widjiati Widjiati, Bambang Purwantara, Adeyinka Oye Akintunde, Tatik Hernawati, Tri Wahyu Suprayogi, Suzanita Utama, Eka Pramyrtha Hestianah
Small ruminant semen is highly susceptible to freeze-thaw oxidative damage due to PUFA-rich membranes, making antioxidant defense central to cryopreservation outcomes. Following PRISMA guidance, we searched Scopus, PubMed, and Google Scholar (2015-2025). Of 250 records screened, 25 studies met inclusion criteria. Effects were pooled as Hedges’ g under random-effects models (primary analyses in OpenMEE, DerSimonian-Laird; sensitivity verified with REML). Percentage outcomes (motility, viability) were arcsine-square-root transformed before SMD calculation. Subgroups contrasted endogenous vs exogenous antioxidants; heterogeneity (I2) and 95% CIs are reported. For motility, endogenous antioxidants showed a small decrease versus controls (SMD = –0.182; 95% CI –0.359 to –0.004; p = 0.045; I2 = 12%), while exogenous antioxidants showed no clear effect (SMD = 0.025; 95% CI –0.144 to 0.194; p = 0.773; I² = 0%). The overall effect on motility was non-significant (SMD = –0.080; 95% CI –0.199 to 0.039; p = 0.186). For viability, both subgroups improved outcomes versus controls, with a larger pooled effect for exogenous (SMD = 5.150; 95% CI 2.810 to 7.490; I2 = 59.94%) than endogenous (SMD = 4.105; 95% CI 0.100 to 8.109; I2 = 92.14%); the overall pooled estimate was positive (SMD = 4.621; 95% CI 2.070 to 7.172). Sensitivity analyses (excluding higher-risk studies and using MD on the original percentage scale) did not materially change interpretations. The data suggest that endogenous antioxidants improve post-thaw viability but may not reliably sustain motility, whereas exogenous antioxidants may offer superior advantages to viability under particular circumstances. These results should be approached with caution due to significant variability in reporting and substantial differences in viability. Standardized methods, fixed dosages, and consistent outcome metrics are crucial to clarify the timing and recipients of external supplementation that improves beyond innate defenses. © 2026, Walailak University. All rights reserved.
Faculty of Veterinary Medicine, Universitas Airlangga, East Java, 60115, Indonesia; Department of Veterinary Reproduction, Faculty of Veterinary Medicine, Universitas Brawijaya, East Java, 65151, Indonesia; Division of Reproduction and Obstetrics, School of Veterinary Medicine and Biomedical Sciences, IPB University, West Java, 16680, Indonesia; Department of Agriculture and Industrial Technology, Babcock University, Ogun State, 121003, Nigeria
