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The aim of this study was to evaluate the use of human chorionic gonadotropin at the time applied is performed embryo transfer (day 7) on pregnancy rate in embryo recipient cows in dual purpose cattle, as recipients are used F1 cows (Holstein x Zebu and Zebu x Creole), totaling 300 cows cycling, regardless of the number of births. To synchronize, we used an ear implant containing 3 mg of progestogen norgestomet for 9 days, plus an intramuscular injection (IM) of 3 mg of norgestomet and 5 mg estradiol valerate. At implant removal, was applied 400 IU of equine chorionic gonadotropin (eCG) in both groups. The cows that showed oestrus, were transferred on day 7 of having submitted, only the cows were transferred to a rectal palpation had a corpus luteum of quality 2 and 3, using frozen embryos. The study was divided into two groups: group 1 (control with 70 cows) and group 2, treated with 1500 IU of eCG with 72 cows. Pregnancy diagnosis was performed at 60 days, the embryo transfer. The results were evaluated with a randomized design and statistical analysis, we used a Student t-test to determine the difference between the two groups. The results of this study show a significant difference (P <0.05) in pregnancy rates, demonstrating that treatment with eCG at the embryo transfer increases pregnancy rates in cows transferred. Concluding that eCG treatment (1500 IU) resulted in higher pregnancy rate for the group treated 37 pregnant cows (51.3%) vs. the control group 29 cows pregnant (41.4%) (P <0.05).
Palacios et al. (Wed,) studied this question.