The effects of various dosages of equine chorionic gonadotropin (eCG) on superovulation induction for in vivo and in vitro embryo production were examined in stray cats (Felis catus). Cats (n=286) were allocated into five treatment groups with 0, 50, 100, 200, or 400 IU eCG, followed by 100 IU human chorionic gonadotropin (hCG). In vivo- and in vitro-produced blastocysts were obtained by artificial insemination (AI) and in vitro fertilization (IVF), somatic cell nucleus transfer (SCNT), or parthenogenetic activation (PA). The percentage of cats that developed mature follicles, the percentage of cats with collected embryos, and the mean number of in vivo blastocysts per cat were higher in the 200 IU treatment group (43.9%, 31.8%, and 1.53, respectively) compared with those of the other groups (P<0.05). The percentage of follicular developed cats, the percentage of cumulus-expanded oocytes, and the mean number of collected cumulus-oocyte complexes per cat in the 200 IU (56.7%, 67.8%, and 26.2, respectively) and 400 IU (53.3%, 64.2%, and 26.7, respectively) groups were higher than those in the other groups (P<0.05). Furthermore, the percentage of in vitro-produced blastocyst per cleaved embryos and the average cell number of the blastocysts from IVF (52.7% and 125.8, respectively) was higher than those of the blastocysts from PA (30.1% and 85.2) and higher than those of the blastocysts from SCNT (15.3% and 37.5; P<0.05). In conclusion, the current study demonstrated that in vivo and in vitro embryo production were affected by the dosage of eCG; the best results were obtained with 200 IU.
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