Effects of different activation protocols on cleavage rate and blastocyst production of caprine oocytes

The present study was undertaken to assess the effect of different chemical activators along with 6-DMAP on in vitro matured caprine oocytes. From 4332 ovaries, 14235 cumulus oocyte complexes (COCs) were collected which were matured in TCM-199 medium containing follicle stimulating hormone (FSH) (5 µg/ml), Leutinizing hormone (LH) (10 µg/ml), oestradiol-17β (1 µg/ml) supplemented with 10% fetal bovine serum, 10% follicular fluid and 3 mg/ml bovine serum albumin (BSA) at 38.5°C and 5% CO₂ in an incubator under humidified air for 27 h. In group 1 (control), 3117 in vitro matured oocytes were co incubated with sperms for 18 h in ferttalp medium. In group 2, 3563 in vitro matured oocytes were activated with 7% ethanol for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR₂aa medium. In group 3, 3109 in vitro matured oocytes were activated with 5 μM ionomycin for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR₂aa medium. In group 4, 3455 in vitro matured oocytes were activated with 5 μM calcium ionophore for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR₂aa medium. Oocytes were cultured in 50 µL drops of research vitro cleave (RVCL) medium for embryo development. The cleavage rate, morula and blastocyst production in group 1, 2, 3 and 4 were 26.07 ± 2.37%, 14.91 ± 2.91 & 1.45 ± 0.71%, 49.57 ± 3.79%, 20.07 ± 2.38% & 5.29 ± 1.42%, 50.18 ± 3.59%, 15.26 ± 2.87% & 1.85 ± 0.72% and 80.26 ± 2.30%, 35.33 ± 2.67 & 7.10 ± 0.89%, respectively. These results indicated that the activation of in vitro matured oocytes by 5 μM calcium ionophore for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h is most favorable for parthenogenetic caprine embryos production.