The success of transvaginal follicular aspiration in mares can be influenced by several factors, such as vacuum pump pressure levels. The present study aimed to investigate the effect of different negative pressures (150, 280 and 400mmHg) of the vacuum pump on the oocyte recovery in the mares. The mares (n=10) were undergoing follicular aspiration using three different negative pressures for three consecutive estrous cycles as follows: G150 = 150mmHg (n = 10); G280 = 280mmHg (n = 10); G400 =

more »

... mmHg (n = 10). Every estrous cycle, the group that the mare would participate was drawn, and each animal participated once in each group. Only preovulatory follicle was used, about 30 to 36 hours after application of hCG. To compare the results, the chi-square test was used (5% significance) and Fisher exact test, when recommended. Thirty preovulatory follicles (diameter 36.1±1.80mm) were aspirated and ten oocytes were recovered (33.3%). There was no statistical difference between the experimental groups (p=0.59). Thus, accord to the results observed in this study, we could conclude that the negative pressure of the vacuum pump used was not efficient to increase oocyte recovery.