Effect of Seasons on Ovarian Activity and Developmental Competence of Buffalo Oocytes and Embryos

Abstract

T HE AIMS of the current study were to investigate the effects of seasons on 1) oocyte yield, aspiration rate, and quality in buffalo. 2) Maturation rate and embryo developmental competence in buffalo. Buffalo ovaries [426] were collected during different seasons of the year [2021], cold seasons (from October to March) and hot seasons (from April to September), and the temperature humidity index (THI) was calculated, counting the number of ovarian follicles, and the aspiration rate and yield were recorded. Oocytes' quality was classified as excellent, good, fair, and denuded. Excellent and Good quality oocytes were in vitro matured (IVM) in tissue culture media -199 (TCM-199) + fetal calf serum 10% (FCS) + 10 μg/ml folliclestimulating hormone (FSH) + 50 μg/ml gentamicin. Oocytes were incubated for 22 h in 5% CO 2 and 38.5°C., cumulus-cell expansion and nuclear maturation were determined. Frozenthawed semen was used to fertilize mature oocytes, which were then incubated for 18 hours before being cultured in vitro for 7 days by synthetic oviduct fluid (SOF). Results demonstrated that the total and mean number of buffalo oocytes yield in the cold seasons was significantly (P˂0.05) higher when compared to hot seasons. Aspiration rate is not significantly affected by season. Cold seasons are characterized by an increased number and percentage of excellent and good oocytes Also, the hot seasons significantly (P<0.05) decreased cumulus-cell expansion and nuclear maturation of IVM buffalo oocytes. The transferable embryo rate was significantly (P˂0.05) higher in cold seasons when compared with hot seasons. In Conclusion, the hot seasons could impair reproduction in buffalo by decreasing the oocyte yield and quality. In vitro maturation and transferable embryo rates significantly increased during the cold seasons in Buffalo.