This study aimed to evaluate the effects of active immunization against swine follicular liquid in Limousin cows and heifers, based on progesterone plasma levels, estrous cycle length and ovulation rate. Two immunization procedures were performed with 15 days interval, administering an immunogenic substance containing the proteic content of 25ml of swine follicular fluid, plus 1ml aluminum hydroxide gel, subcutaneous. The ovulation was measured by rectal palpation and ultra-sonographic evaluation, seven to nine days after each estrus period. Results show that after the last immunization, the animals presented higher double ovulation incidence (41.7%). The average ovulation before and after immunization were 1.00±0.00 and 1.40±0.31 ovulations/cycle, respectively (P<0.01; chi2). The immunization method used was effective to stimulate a higher ovulation number. No differences on mean estrous cycle length and progesterone levels were observed. Physiological inhibin action may be an alternative method to induce multiple ovulations of bovines.
Bovine; follicular fluid; inhibin; ovulation
