Indução de múltiplas ovulações utilizando baixa dose de GnRH (deslorelina) em éguas

Abstract

This study was aimed to induce multiples ovulations in mares using low doses of GnRH at a fixed time and determinate its impact on reprodutive efficiency and economic results in a commercial program for embryo transfer, in northeastern Brazil. In the experiment 01 was used 15 embryo donor mares, 10 were Quarter Horse Breed and 5 were Magalarga Machador Breed, aged between 8 and 20 years. After being monitored and inseminated during estrus and performed the embryo collection constituting the G1, it was applied 7.5mg of dinoprost-tromethamine the G2 consisting of the sames mares of G1, experiment was started wilh examinations twice a day to detect the highest follicle with 23to 25 mm and the second > 18 mm, ideal moment to start the treatment, with 100 μg of deslorelin acetate, with an interval of 12h, until the largest follicle reaches 33 to 35 mm in diameter, when the ovulation induction was realized with 1mg of deslorelin acetate associated IM to 1000 UI of hCG IV. In the experimente 02 were used 7 donors, 4 were Quarter Horse Breed and 3 were Magalarga Machador Breed, aged between 8 and 20 years. The groups G1 and G2 are equal to the experimente 01, being increased the G3 that begins after the reapplication of 7.5 mg of dinoprosttromethamine after the G2 collection, after 48h the treatment is started with 100 μg (1ml) of deslorelin adetate, bib, until the lasgest follicle reaches 34±1 mm in diameter or 6 days of application. In the experiment 01 the mares percentage with multiple ovulations in the control cycle (G1), experimental cycle (G2) were (2/15) 13.33% and (13/15) 86.66%, respectively (P<0.05). It was also obsorved an increase in the embryos recovered numbers being in the control group only 9 when in the experimental group were 16 embryos (P<0.05), with an embryos/mares average of 0.6±0.48 in the control group and 1.066±0.497 in the experimental group (P>0.05); with an embryo recovery rate of 60% G1 and 80% in G2 (P<0.05). It was observed an increase in the number of recovered embryos being in G1 3, G2 6 and G3 0 (P<0.05), with an embryo/mare recovery average of 0.4 3± 0.53 in G1, 0.86 ± 0.38 in G2 and 0 in G3 (P>0.05); with an embryo recovery rate of 43% G1, 85.71% in G2 and 0% in G3 (P<0.05).It can be conclude from the results that the administration of GnRh low-dose in embryo donors, interfered positively in the growth of the dominat follicle and second dominant follicle, increasing the incidence of multiple ovulations, incrementing the embryo recovery rate per cycle, improving the reproductive efficiency of treated donors and that the treatment when started early, with follicles < 25 mm, presents below-expected results, it is not efficient to induce double ovulation.