The Effects of Serum, Steroid and Gonadotropins on In vitro Maturation and Fertilization of Bovine Oocytes

The effect of serum, steroid and gonadotropins on maturation of bovine oocytes and subsequent embryo development were evaluated. This study was designed to investigate factors affecting IVP of bovine embryos and 16 treatment groups were formed including different combinations of FSH, LH, E2, ECS, FCS. Ovaries were obtained from cows at a slaughterhouse and transported to the laboratory in PBS at 33 degrees C. Collected oocytes from antral follicles were cultured for 24 h in a 400 L of maturation medium (TCM-199) overlaid with mineral oil under 5% CO(2), 95% humidity in air at 38.5 degrees C. Oocytes with expanded cumulus were transferred to the fertilization medium and coincubated with frozen-thawed and heparin treated spermatozoa for 15 h. After the incubation, oocytes were transferred to culture medium and developmental stages were recorded. Maturation rates were not significantly different among 14 treatments except control group (33%) and group 13 containing LH (66.7%). There was a low cleavage rate (35.7%) in the control group as in maturation results. Similarly, group 3 containing ECS, FSH and LH showed lowest cleavage rate (41.7%). On the contrary, highest cleavage rate (75.9%) was observed in group 14 containing LH and E2. Differences between maturation groups on cleavage rates were significant at p<0.05 level. Different serum and hormon supplementations to maturation media do not have any advantage against each other, but fertilization rates were clearly high in the groups supplemented with E2. Especially, supplementation of LH and E2 together in the maturation media increased fertilization rates significantly.