In vitro maturation of caprine oocytes in different concentrations of estrous goat serum

The aim of the study was to evaluate the optimum concentration of the estrous goat serum for goat in vitro oocyte maturation. Goat ovaries were collected from a local abattoir and transported within 3 h to the laboratory in a warm saline solution (30–35 °C), supplemented with 100 IU penicillin G and 100 μg streptomycin sulfate/ml. Cumulus-oocyte complexes (COC's) were obtained by puncture of 1–4 mm diameter follicles with a 18G needle attached to a disposable syringe, washed 10 times in TCM-199 hepes modification with Earl's salts and supplemented with 50 μg/ml gentamycin, 100 μg/ml l-glutamine and 0.25 mM sodium pyruvate without any serum supplementation. The COC's were randomly divided into four groups. Group 1 (n = 105) COC's were fresh control and cultured in TCM-199 medium without serum supplementation. Group 2 (n = 105) COC's were washed five times and cultured in TCM-199 medium supplemented with 10% EGS. Group 3 (n = 110) COC's were washed five times and cultured in TCM-199 medium supplemented with 15% EGS. Group 4 (n = 112) COC's were washed five times and cultured in TCM-199 medium supplemented with 20% EGS.After 24–27 h of IVM, oocytes were denuded with the aid of 0.1% hyaluronidase and passing them through a fine pipette, fixed for 24–48 h in a mixture of acetic acid and alcohol (1:3) at room temperature, stained for 10 min with 1% (w/v) orcein in 45% acetic acid and examined for the evidence of different stages of maturation. Significantly higher (p < 0.01) maturation rates of oocytes (61–78%) were observed in all concentrations of estrous goat serum compared to those without serum supplementation. However, no significant difference was observed between the 10 and 15% serum supplemented group. A significant difference in maturation percentage (p < 0.01) was observed between 10 and 20% serum supplementation in culture media. In conclusion, it can be said that the supplementation of 20% EGS in TCM-199 medium could be used to achieve optimal maturation rate.