Cyclic embryo recipient mares submitted to different hormonal protocols.
estrogen, progesterone, receptor, mares.
Embryo transfer (ET) has become the most widespread biotechnology in equine reproduction, being used on a large scale by stud farms and breeding centers to obtain more products per year. The synchronization of the estrous cycle between the recipient and the donor is a critical point within the technique, making it necessary to have at least three recipient mares for each donor, so that at least one is able to receive the embryo on the day of transfer. The combination of estrogens and progestogens is used in acyclic embryo recipient mares, in transition or when there is little availability of recipient mares, making a close synchrony between donor and recipient necessary. The aim of this study was to compare three hormonal protocols, using 17β estradiol and altrenogest, and to evaluate pregnancy rates in cyclic recipient mares. Twenty-four cycles of Mangalarga Marchador mares were analyzed, divided into three groups containing eight cycles in each. In which, all mares received 15 mg of PGF2α on the first day of treatment, G1 include 17 beta estradiol on day 1 (20mg), day 2 (10mg) and 300 mg of altenogest on day 3, G2 1 (1omg), day 2 (10mg), day 3 (20mg), day 4 (10mg) and 300 mg Altrenogest on day 5, G3 Introduction 17 beta estradiol day 1 (10mg), day 2 (20mg) and 300 mg Altrenogest on day 3. Four days after treatment with Altrenogest, as recipients were able to receive the embryo, 1500mg / animal of long-acting progesterone was administered on the day the ET was performed. After seven days of ET, a diagnosis of pregnancy and a new application of progesterone in pregnant mares was carried out, which was carried out weekly until the 120 days of pregnancy. All groups registered as estrogen applications, with a high degree of edema being achieved in all pregnant mares. A higher degree of uterine edema (p <0.05) was observed in mares diagnosed with negative pregnancy, on day 3 of treatment in G1 and G3 and on day 4 in G2. There was no statistical difference in pregnancy rates in the three groups studied. Thus, the three protocols are able to be used in the practical routine of the equine breeding veterinarian.
Key words: estrogen, progesterone, receptor, mares.