Augmentation of developmental competence of immature cattle oocytes supplemented with growth factors in culture media

The aim of the present study was to produce cattle embryos through in vitro maturation, fertilization and culture by supplementing culture media with insulin-like growth factor-1 individually and in combination with epidermal growth factor. Cattle ovaries were collected from the abattoir and carried to the laboratory within 3–4 h in normal saline, maintaining 30–35 °C. Cumulus oocyte complexes (COCs) were collected from visible surface follicles and matured in-vitro in maturation media supplemented with (i) insulin-like growth factor-1 and (ii) in combination with epidermal growth factor at 38.5 °C in CO₂ incubator with maximum humidity. After 24 h matured, oocytes were allowed for fertilization with capacitated sperms in Fert-BO media at 38.5 °C in CO₂ incubator. After 15–18 h, oocytes were cultured in 100 μl droplets of mCR2^aa medium supplemented with growth factor. After 48 h, cleavage was checked and further co-cultured with oviductal cells for development. In the first experiment, the cleavage rate (63.27±2.17^a) and morula formation rate (20.09±2.57^a) were significantly (p<0.05) higher in the treatment group @ 50 ng/ml of IGF-1 as compared to the control group. In contrast, in the second experiment the cleavage rate (70.00±2.16^a) and morula formation rate (25.30±1.45^a) were significantly (p<0.05) higher in the treatment group @ 50 + 10 ng/ml of IGF-1+ EGF, as compared to control group. From the present study, it could be concluded that insulin-like growth factor-1 may have induced cleavage after fertilization and helps in early embryo developmental growth.

• IGF-1 @ 50 ng/ml and in combination with EGF @ 10 ng/ml enhanced the cleavage rate and helped in early embryonic developmental growth significantly.