ABSTRACT In order to study and characterize the lesions in the reproductive tract of Nellore heifers naturally infected with Ureaplasma diversum and presenting granular vulvovaginitis syndrome (GVS), fragments of uterine tube, uterus, cervix, vagina and vulva of 20 animals were evaluated. The macroscopic lesions of the vulvovaginal mucosa were classified in scores of “1” mild, until “4”, severe inflammation and pustular or necrotic lesions. The histopathological evaluation was performed using scores of “1” to “4”, according to the inflammatory alterations. The fragments with severe microscopic lesions (3 and 4) were from the uterine tubes and uterus, which showed leukocytes infiltration and destruction and/or necrosis of epithelium. Alterations in the lower reproductive tract fragments were mild, but characteristics of acute inflammatory processes. The histopathological findings of the reproductive tract of females naturally infected with Ureaplasma diversum are consistent with injuries that compromise the environment from the local where spermatozoa acquires ability to fertilize an oocyte until those where the oocyte is fertilized. Therefore, animals with GVS should be identified early in the herd, because, besides the reduction in the fertility rates caused by tissue damages, they can contribute to disseminate the microorganism. Key words: bovine, tissue evaluation, reproduction, Ureaplasma diversum.

Objetivou-se com este estudo avaliar o efeito do fornecimento de Acetato de Melengestrol (MGA®Premix) após IATF (inseminação artificial em tempo fixo), sobre a taxa de concepção em vacas paridas da raça Nelore. Experimento I, avaliou-se o efeito do fornecimento de 2,28g de MGA/ vaca/ dia, do dia 13 (D13) ao dia 18 (D18) após a IATF. As vacas foram divididas em dois grupos, sendo o Grupo I (n=83, controle) que foi realizado apenas IATF e Grupo II (n=104, tratado) que foi fornecido o MGA após a IATF. Experimento II, avaliou-se o efeito do fornecimento de 2,28g de MGA/ vaca/ dia, do dia cinco (D5) ao dia 10 (D10) após a IATF. As vacas foram divididas em dois grupos, sendo o Grupo I (n=94, controle) que foi realizado apenas IATF e Grupo II (n=100, tratado) que foi fornecido o MGA após a IATF. O diagnóstico de gestação foi realizado 45 dias após a IATF em ambos os experimentos. As taxas de concepção foram comparadas pelo teste de Qui-quadrado. No Experimento I, as taxas de concepção foram de 42,16% para o grupo controle e 50,0% para o grupo tratado. No Experimento II, a taxa de concepção do grupo controle (47,87%) foi significativamente maior do que o grupo tratado (28,0%). Conclui-se que o fornecimento de MGA®Premix, administrado do D13 ao D18 após a IATF não afetou a taxa concepção. Entretanto, quando fornecido do D5 ao D10, reduziu a taxa de concepção em vacas Nelore paridas.

The objective of the present study was to assess the effect of administration of Melengestrol Acetate (MGA® Premix) after FTAI, on the conception rate in lactating Nelore breed cows. Experiment I, assessed the effect of administration of 2.28 g MGA/cow/day, from day 13 (D13) until day 18 (D18) after FTAI. The cow were divided into two groups, Group I (n=83, control) that cows were submitted just to FTAI and Group II (n=104, treated) that cows received MGA after FTAI. Experiment II, assessed the effect of administration of 2.28g MGA/cow/day, from day 5 (D5) until day 10 (D10) after FTAI. The cow were divided into two groups, Group I (n=94, control) that cows were submitted just to FTAI and Group II (n=100, treated) that cows received MGA after FTAI. Gestation was diagnosed in both experiments 45 days after FTAI. The conception rates were analyzed by Qui-Square test. In experiment I, The conception rates were 42,16% for control group and 50,0% for treated group (p>0,05). In Experiment II, the conception rate of control group (47,87%) was higher than treated group (28,0%). It was conclude that administration of MGA®Premix from D13 until D18 after FTAI didn't affect the conception rate. However, when administered from D5 until D10, reduced the conception rate in lactating Nelore breed cows.