Determination of effective media and its hormone supplementation on in vitro maturation of crossbred cow oocytes

Background: The present experiment was conducted to determine an effective basic medium and its hormone supplementation for in vitro maturation of cow oocytes. Methods: The experiment was conducted at the Department of Animal Nutrition, Genetics, and Breeding at Sher-e-Bangla Agricultural University, Dhaka- 1207, from January 2020 to December 2020. This study assessed the efficacy of Tissue Culture Media 199 (TCM-199) and TCM-199 supplemented with varying dosages of Gonadotropin (0.5, 1, 5, 10, and 15 µg/ml) hormone for the in vitro maturation of bovine oocytes. Synthetic ovurelin is used as a substitute of gonadotropin. Cumulus-oocyte complexes (COCs) were collected from cow ovaries by aspiration method and matured for 48 hours at 37.5ºC with 5% CO2 in humidified air in basic and supplemented media. Results: Significantly higher (p<0.05) number of follicles were aspirated in ovaries without corpus luteum (CL) (4.59±0.27) compared with ovaries containing CL (3.05±0.13). Consequently, more COCs were found in ovaries without CL (4.61±0.25) than in ovaries with CL (1.98±0.16). The maturation rate was significantly higher (p<0.05) in (TCM-199 supplemented with gonadotropin 10 µg/ml) medium (65.71±2.74) than in other treatments. A higher maturation rate was found up to 10 µg/ml gonadotropin supplementation, but the maturation rate began to decline when the dose exceeded 10 µg/ml. Conclusion: Therefore, ovaries without CL could be used in TCM-199, supplemented with Gonadotropin (10 µg/ml) as basic medium for optimal in vitro maturation rates of cow oocytes.