Evaluation of pig oocyte in vitro maturation and fertilization using three gonadotropin-based hormonal compounds

Objective:To evaluate the effect of human chorionic gonadotropins(hCG)and equine chorionic gonadotropins(eCG)on in vitro gilt oocyte maturation and embryonic development,using frozen semen for fertilization.Methods:Two independent experiments(6 replicates each)were carried out to evaluate gilt oocyte maturation,and fertilization and embryonic development by using ovaries from a local abattoir.Totally,712 oocytes were randomly distributed in four-well dishes to receive Novormon(eCG 5.0 IU),PG600(eCG 5.0 IU and hCG 2.5 IU),Chorulon(hCG 5.0 IU),or no hormones.Oocytes were incubated with 5%CO2,95%air and saturation humidity at 39℃for 44 h.Maturation of the oocytes to metaphaseⅡwas assessed by using the aceto-orcein technique.In addition,741 oocytes were used and randomly distributed in four-well dishes,and then oocyte maturation was carried out as mentioned,but matured oocytes were washed and placed in fertilization medium with frozen-thawed sperm.Gametes were co-incubated for 7 h,and then washed and placed in development medium,and incubated for further 7 days,at which time embryonic development was evaluated.Fertilization and embryo development media were not supplemented with the studied hormones.Results:Novormon(eCG)and PG600(eCG+hCG)treatments significantly improved the percentages of metaphaseⅡoocytes compared to the control group(P<0.05).Furthermore,a significant increase was also observed in the young blastocyst stage between the control group and the PG600 treatment group(P<0.05).Conclusions:Hormonal products Novormon(eCG)and PG600(eCG+hCG)can obtain the highest percentages of in vitro maturation in gilt oocytes;however,this effect is not transferred to fertilization rates.