Seasonal influence on oocyte recovery rate, quality and In vitro maturation in cows

Recent breakthroughs in vitro maturation, fertilization and culture technology have allowed for an increase in the number of offspring generated from genetically better females, but this progress is still hampered by critical factors affecting oocyte yield and quality. This study aims to evaluate the effect of the seasons on the rate of maturation and recovery of oocytes.

The ovaries were brought from the slaughterhouse in Riyadh, Saudi Arabia, in a 0.9% NaCl saline solution and brought to the laboratory within 2-3 hours at a temperature of 25-35°C. Only the collected oocytes with two layers or more of cumulus cells (CCs) and uniform ooplasm were used. Five repetitions were made in each season of the year, followed by their ripening in the laboratory and a follow-up ripening after 24 hours. Observe the maturity rate after the stain and the expansion of cumulus cells and compare them with other seasons.

The mean maturation rates of MII and MI oocytes were not significantly different between all seasons. Additionally, there were no significant changes in the cumulus-oocyte complex before maturation in all seasons. However, after maturation, a highly significant difference (P<0.001) was found between the spring season before and after maturation (156.31 ±17.68 mm) and the rest of the seasons (summer; 169.89±19.96 mm; autumn; 176.66±20.14 mm; and winter; 188.84±24.50 mm). In order to improve in vitro maturation for following investigations, such as in vitro fertilization or cloning and in vitro embryo development, the ideal season should be chosen for collecting oocytes.