Bezafibrate and Cholic Acid-Mediated Lipid Reduction Improves the Cryotolerance of Vitrified In Vivo-Derived Porcine Embryos.

BACKGROUND: High lipid accumulation limits the cryotolerance of porcine embryos. This study aimed to identify lipid-lowering combinations during in vivo porcine morulae developing into blastocysts and evaluates their effects on post-warming embryonic development and embryo transfer (ET) pregnancy. METHODS: A stable method of in vivo embryo production was established in Meishan pigs to obtain morulae. Morulae were treated with bezafibrate and cholic acid alone, in combination, or with either compound replaced by L-carnitine or niacin, respectively. Treated embryos were vitrified-warmed, followed by determinations of lipid content, cell division and ET. RESULTS: The protocol achieved 95.00% synchronization, with 22.61 embryos obtained per sow in Meishan pigs. The combination of 50 μM of bezafibrate and 50 μM of cholic acid was identified as the optimal non-toxic treatment and produced the lowest lipid droplet content (p < 0.05), indicating a synergistic lipid-lowering effect. This treatment improved post-warming embryonic division (p < 0.05) and was associated with a numerically higher pregnancy rate after ET (71.43% vs. 50.00%). However, 200 μM of this combination impaired blastocyst formation and delayed post-warming embryonic development. CONCLUSIONS: Bezafibrate combined with cholic acid reduced embryonic lipid contents and improved cryotolerance, providing a practical strategy for porcine embryo cryopreservation.