Indução da ovulação em éguas durante o período de transição primaveril

Abstract

The anticipation of the breeding season has been the subject of great interest in front of their economic impact. In order to advance the first ovulation and anticipate the reproductive phase of the mares, this study aimed to evaluate if the transvaginal follicle aspiration technique guided by ultrasound during spring transition period, was able to induce cyclicity in mares. The experiment was conducted in Animal Reproduction area of DRAA / IZ / UFRRJ, located at Seropédica-Rj, during spring transition period (August-September) and early reproductive period (October) 2015. Selected mares were randomly distributed into three groups: Group 1 Control (G1, n = 9), without hormonal treatment; Group 2 P4 + PGF2α (G2, n = 9), 1500 mg of long-acting progesterone, intramuscularly (IM), and seven days later, 7.5 mg Dinoprost (PGF2α), IM and Group 3 transvaginal follicular aspiration + PGF2α (G3, n = 9), greater follicle aspirated (>25mm) and seven days later, 7.5 mg Dinoprost (PGF2α), IM. Prior to the beginning of the experiment, all mares were evaluated by ultrasonography, and the criteria for the study was absence of corpora lutea as well as the presence of ovarian follicles larger than 25 mm. Subsequent to this evaluation, the reproductive activity was monitored every 48 hours until the second ovulation of each mare. When evaluated the number of mares ovulating within 16 days after initiation of treatment, it was observed that the groups G2 and G3 were significantly more effective (P = 0.0031) in the first ovulation of the breeding season, when compared to G1. In G1, 16 days after the start of treatment, no animal ovulated. In G2 and G3 eigh (88.9%) and six (66.7%) mares ovulated respectively. The mares were evaluated until the second subsequent ovulation treatment. All mares ovulated normally, showing that none of them returned to the transitional period and the average number of days between the first and second ovulation did not differ between the groups (P> 0.05). The results of this study allow us to conclude that follicular aspiration technique during spring transition period associated with the administration of 7.5 mg of PGF2α seven days later, was able to induce cyclicity in XI mares. This treatment was effective as the conventional protocol P4 + PGF2α, thus possible to use it in routine reproductive centers. However, more studies are needed to evaluate its effectiveness during the early spring transition period, as well as its association with ovulation inducers.