During the reproductive season of 2001 and 2002, 43 recipient mares of the Mangalarga Marchador breed were treated randomly with intra-muscular application of 200mg/day of oily progesterone (P4). Another group of 41 mares of the same breed were treated randomly, via oral, with 0.044 mg/kg/day of Altrenogest. Both treatments were performed between D0 (ovulation day) and D5. The recipients were evaluated on D2 and those in adequate conditions were in ovulated. Two groups of 85 mares of the same breed were used as control by not receive any progestogen. They were also evaluated and, when considered appropriate, in ovulated on D2 or D5. The groups D2/P4 and D5 without progestogen presented a significantly greater percentage of recipients considered appropriate during the evaluation, respectively 55 (64.71%) and 25 (65.12%). In the group D2 with Altrenogest, 20 mares were considered appropriate for in ovulation and 21 were not. The group D2 without progestogen showed a significantly higher percentage of mares considered not appropriate. The pregnancy rate after in ovulation for the groups D2/P4 and D5 without progestogen were respectively 72.72 and 76.36%, significantly higher than those from the other treatments. The pregnancy rate for the group D2 with Altrenogest (52.38%) was not significant. Despite a larger number of non pregnant recipients for the group D2 without progestogen, it was not significant. The treatment of mares with P4 from D0 to D5 indicates it is possible to anticipate the in ovulation of recipient mares to D2 and to obtain similar results to when in ovulated on D5.
equine; Mangalarga Marchador; embryo transfer; progestogen
