Optimization of Ovum Pick-Up and Embryo Transfer Techniques for Enhancing Reproductive Efficiency in Nili-Ravi Buffaloes.

Nili-Ravi buffalo is a core dairy breed for China's genetic improvement, yet its assisted reproductive technologies are restricted by low ovum pick-up (OPU) efficiency and unstable embryo transfer (ET) pregnant rates. This study established statistically optimized key parameters for OPU procedures in Nili-Ravi buffalo, and evaluated the effects of multiple ET-related protocols. For OPU, 50-55 mmHg vacuum pressure balanced oocyte recovery and usable rate best (p < 0.05). Young and adult buffalo performed significantly better than prepubertal heifers (p < 0.05). Four consecutive weekly consecutive OPU sessions did not significantly reduce oocyte yield (p > 0.05). FSH treatment markedly enhanced oocyte quantity, quality and recovery efficiency (p < 0.05), with no significant difference between two FSH protocols (p > 0.05). For ET, three estrus synchronization protocols showed no significant effects on estrus, ovulation, transferable recipient and pregnant rates in breeding or non-breeding seasons (p > 0.05), though optimized protocols showed a numerical improvement. Combinations of CL grade and embryo quality, as well as post-transfer treatments with vitamin ADE, hCG and progesterone, did not significantly affect pregnancy or early abortion rates (p > 0.05). This study built a practical reference framework for OPU-ET procedures in Nili-Ravi buffalo, with key OPU parameters statistically optimized and ET protocols showing numerical improvements that require further validation with larger sample sizes.