Twelve Bos indicus (Nellore) embryo donors were confined receiving 25 kg maize silage and 2.5 kg concentrate supplement per day. The proteic supplements used were SOYA (S), SOYA+UREA (S+U) and UREA (U). After 20 day, embryo donors were superovulated and their embryos collected and cultivated in vitro until eclosion. There was no significant statistical difference between the three groups in total number of structures collected (4.17, 8.42 and 7.00), number of viable embryos (2.25, 3.50 and 4.33), oocytes (1.42, 3.92 and 1.08) or degenerated embryos (0.5, 1.0 and 1.83), as well as in vitro eclosion rate (81.48, 78.57 and 84.62%), for the groups S, S+U and U, respectively. The 66 recipients were kept on Braquiaria decumbens pasture with 1.25kg of concentrate supplements for the S, S+U and U groups. Frozen embryos were thawed and transferred after 37 days. There was no significant statistical difference in pregnancy rates at 30 days (25, 28 and 28.57%), and 60 days of pregnancy (16.67, 28 and 25%). It may be concluded that urea can replace the soybean meal in concentrated rations for supplementation of bovine embryo donors and recipients since there were no negative effects in embryo quality, eclosion rate and recipient fertility.
bovine; embryo; protein; supplementation; transfer; urea
