Effects of Various Activators on Bovine Embryonic Development Following Intracytoplasmic Sperm Injection

The objective of this study was to compare the effectiveness of various combination activators of bovine oocyte following intracytoplasmic sperm injection (ICSI) in terms of cleavage and embryo development. Bovine ICSI oocytes were treated with a variation of treatments of combined or single activators as follows; 30 V for 15 x 2 ?sec of electrical pulse +10 ?g/mL cycloheximide (CHX), 7% ethanol + CHX, 5 ?M Calcium ionophore A23187 (Ca-I) + CHX, Ca-I + 1.9 mM 6-dimethylaminopurine (6-DMAP), CHX alone, Ca-I alone. The highest cleavage (73.5%-79.7%), and blastocyst rates (28.0%-35.3%) were obtained in Ca-I + 6-DMAP, ethanol + CHX and electrical stimuli + CHX groups. The treatment with CHX only or Ca-I only gave a significantly lower (P < 0.05) yield of cleavage rate and blastocyst than those treatments with Ca-I + 6-DMAP, ethanol + CHX, electrical stimulation and Ca-I + CHX. In conclusion, these results show that post activation of ICSI oocytes with Ca-I + 6-DMAP, ethanol + CHX, electrical pulse + CHX and Ca-I + CHX are more effective treatments for increasing blastocyst development than those CHX only or Ca-I only, how-ever, activation with ethanol + CHX is recommended.