Targeting Inhibin Enhances Wagyu Oocyte Competence and Embryo Quality: A Comparative Study of In Vivo Immunization and In Vitro Antibody Supplementation

High-efficiency Ovum Pick-Up (OPU) and in vitro embryo production (IVP) are critical for the genetic improvement of high-value Wagyu cattle. However, oxidative stress and mitochondrial dysfunction during oocyte maturation remain major bottlenecks limiting blastocyst yield. This study investigated the role of inhibin in Wagyu oocyte competence through two independent proof-of-concept approaches. In the in vivo active immunization model, thirty Wagyu donors were immunized with a recombinant inhibin protein (INHA group), resulting in a significant increase in the number of recovered cumulus–oocyte complexes (COCs) (461 vs. 279, p < 0.05) and the proportion of high-quality oocytes compared to controls. Oocytes from the INHA group exhibited improved cytoplasmic maturation and mitochondrial function, characterized by higher membrane potential (ΔΨm, JC-1 ratio: 1.55 ± 0.06 vs. 0.83 ± 0.08, p < 0.05), elevated ATP content (2.35 ± 0.07 vs. 1.63 ± 0.03 pmol/oocyte, p < 0.05), and increased NADPH levels. Furthermore, the INHA group showed significantly reduced reactive oxygen species (ROS) accumulation and an increased GSH/GSSG ratio (8.48 ± 0.18 vs. 6.25 ± 0.09, p < 0.05), indicating restored redox homeostasis. Independently, in the in vitro anti-inhibin antibody (AIA) supplementation model, AIA supplementation during oocyte maturation significantly improved the nuclear maturation rate (92.96% ± 1.04%), blastocyst formation rate (56.63% ± 2.36%), and total cell number compared to controls (p < 0.05). Notably, AIA-derived blastocysts achieved a significantly higher pregnancy rate (78.65% ± 1.57%) following transfer. Collectively, these findings demonstrate that targeting inhibin mitigates oxidative injury and stabilizes mitochondrial bioenergetics, providing two distinct, physiology-based strategies for optimizing Wagyu oocyte yield and embryo production.