Effect of IVM media supplementation with a blend of n6/n3 fatty acids on the quality of bovine oocytes and blastocysts

Abstract

Optimizing in vitro maturation (IVM) media can enhance blastocyst yield and quality. This study explores the effects of supplementing IVM medium with a blend of two essential polyunsaturated fatty acids (LA and ALA) at a ratio observed in the serum of experimental heifers on the quality of bovine oocytes, cumulus cells (CC), and blastocysts. The in vitro embryo production protocol was based on commercial media (Bioscience, UK). Oocyte-cumulus complexes (COCs) from slaughterhouse-derived ovaries were matured in a 100 μM LA + ALA blend at a 3:1 ratio (75 μM LA + 25 μM ALA). Following maturation, selected COCs underwent reactive oxygen species (ROS) and glutathione (GSH) measurements in oocytes and apoptosis detection in CC (TUNEL). The remaining oocytes were fertilized and cultured to the blastocyst stage, where cell counts and apoptosis levels were assessed. Our findings indicate that the LA + ALA blend positively influenced specific quality parameters in oocytes (reduced ROS level) and blastocysts (increased total cell number (TCN) and a lower apoptotic index (AI)). However, the treatment did not significantly affect other parameters, such as AI in CCs, cleavage, and blastocyst rates or ICM: TCN and ICM: TE ratios. This study demonstrates that a moderate (100 μM) fatty acid (FA) dose benefits oocytes and blastocysts. Given the opposing effects of individual FAs and the limited data on FA blends, our results suggest that ALA may counteract the adverse effects of LA. Mitigation of oxidative stress and AI and an increased TCN underscore the importance of optimized FA supplementation in IVM media.