Factors affecting oocyte developmental competence in buffalo

The efficiency of reproductive technologies in buffalo is limited by the low number of competent oocytes and the reduced oocyte competence during the non-breeding season, impacting on embryo production costs. This review focuses on the factors influencing oocyte developmental competence in buffalo, emphasizing the role of season and its effects on the follicular environment. Studies integrating transcriptomic, miRNA and metabolomic analyses revealed that the decreased oocyte competence recorded during the non-breeding season is associated with altered expression of genes and miRNAs involved in energy metabolism, oxidative balance, homeostasis and inflammatory status, as well as in changes in the cargo of the extracellular vesicles within the follicular fluid, resulting in variations in the metabolites content of the follicle. These molecular shifts reflect a state of negative energy balance and oxidative stress that may affect oocyte competence and embryo development. Corrective strategies have been proposed to counteract these effects, including dietary supplementation with green tea extract, which enhances follicular growth, antioxidant capacity and oocyte competence and the in vitro addition of extracellular vesicles from the breeding season, which improves embryo yields from oocytes collected during the non-breeding season. These findings highlight that multiple factors play a role in the acquisition of oocyte competence and demonstrate that a multi-omic integrated approach may allow the identification of biomarkers and the design of in vivo and in vitro interventions to improve reproductive efficiency in buffalo.