The prevalence and the etiology of bovine mastitis in the dairy region of the county of Rondon of Pará were investigated. The sensibility and the resistance of the isolated agents to the antimicrobiotics was evaluetad; 237 mixed-bred milk cows were used on nine properties, which were hand milked once a day and kept on Brachiaria brizantha pasture, with supply of mineral salt and water ad libitum. Clinical examination of the mammary gland, the test of the sieve and California Mastitis Test were performed. Of the 935 examined mammary quarters, 6.6% had subclínical mastitis, 1.3% clinical mastitis, and 92.1% were negative. The isolated bacteria in the clinical mastitis were coagulase negative Staphylococcus spp. (25%), Staphylococcus aureus (16.7%), Streptococcus spp. (8,3%), and Corynebacterium spp. (8.3%). In the subclínical mastitis coagulase negative Staphylococcus spp. (32.3%), Staphylococcus aureus (17.7%), Staphylococcus intermedius (1.6%), Streptococcus spp. (4.8%), Corynebacterium spp. (4.8%), and coagulase negative Staphylococcus spp./S.aureus (1.6%) were isolated. There was no microbial growth in 41.7% of the samples with clinical mastitis and in 37.1% with subclínical mastitis. In the antibiogram, 100% of the isolated negative coagulase Staphylococcus spp., S. aureus, S. intermedius, and Streptococcus spp. were sensitive to sulfazotrim. On the other hand, Corynebacterium spp. were 100% resistant to this same antimicrobiotic. Cefalotina, cefoxitina and gentamicina were efficient against the isolated Staphylococcus spp. which represent the greater part of the mastitis agents in this study. Mastitis was diagnosed in all flocks studied, however the number of affected animals was considered low; this probably is due to low milk production of the cows and to permanence of the calf with the mother after milking, what favors emptying the mammary gland. But hygienic sanitary measures and management practices have to be improved.
Bovine mastitis; etiology; Staphylococcus spp.; antibiogram; Pará
