Development of Embryos Recovered From Doe Rabbits Treated With Green Tea Extract and Cultured Under High Thermal Conditions in Vitro

Abstract

This study aimed to evaluate whether orally treatment of doe rabbits with green tea extract (GTE) can eliminate the negative effects of hyperthermia on embryonic development in vitro. A total of 24 mature NZW does was randomly allotted into three groups, 8 in each. The 1 st group was control, while the 2 nd and 3 th groups were orally treated with 1 ml distilled water contained 200 and 400 mg GTE/kg LBW, respectively, for one month and naturally mated with proven bucks. Embryos were recovered from slaughtered doe oviducts at blastocyst stage 72 h post-mating by flushing and morphologically evaluated. Only normal embryos at blastocyst stage were in vitro cultured at 38.5 °C for 48 h (normal temperature, NT) or at 41.5°C (hyperthermia, HT) for 6 h then at 38.5 °C for 42 h in 5% CO 2 and 95% humidity to develop to expanded and hatched blastocysts. Results showed that embryo recovery rate was not significantly affected by GTE. Embryos of does treated with both GTE levels were better (P<0.05) than control embryos. The GTE at 400 mg/kg showed the highest normality rates, hatched blastocyst proportion, and the lowest degenerated embryos. Formation rate of expanded and hatched blastocysts was higher (P<0.05) for embryos cultured in vitro at NT than at HT, while proportion of degenerated embryos showed an opposite trend. Effect of interaction between GTE treatment and thermal condition was significant on proportion of expanded, hatched and degenerated embryos (P<0.05), reflecting an increase in hatched embryos and decreasing degenerated embryos proportions by increasing GTE level at NT and HT, but GTE treatment showed the highest hatched and the lowest degenerated embryos proportions with level of 200 mg/kg at NT and with level of 400 mg/kg at HT. In conclusion, the negative effect of heat stress on embryonic development in vitro may be eliminated by GTE treatment of heat stressed does.