In an attempt to establish good storage conditions for embryos of Nelore cows, 29 embryos were cooled in modified Celle model container during 24 hours at 5°C. Embryos were evaluated, classified and transferred to recipient heifers synchronized by prostaglandin and progestagen. Before cooling embryos were 82.8% (24/29) as level I, 13.6% (3/29) as level II and 6.9% (2/29) as level III. After a 24-hour period of cooling, 62.1% (18/29) of the embryos were level I, 20.7% (6/29) level II and 17.2% (5/29) level III. After the cooling process, all embryos were at the same stage of development as they were at the beginning of the process, however, 82.8% (24/29) of the embryos that were between blastocyst and expanding blastocyst stage showed a collapsed blastocoele. Transferred heifers showed that 37.9% (11/29) became pregnant, differing from heifers in the control group (75.6% - 62/82). The method used to syncronise the recipients, probably, has influenced this result, since only one became pregnant among the 11 recipients that received progestagen.
Bovine; embryo; cooling