Incidência de contaminação no processo de obtenção do leite e suscetibilidade a agentes antimicrobianos

Abstract

Two experiments were carried to evaluate the efficiency of the predipping on bacterian contamination reduction of the animal teats and on the milk bacterian count, as well as the sanitation efficiency of the mechanical milking machine s teatcups. Also has been evaluated, the profile of susceptibility to antimicrobials of coagulase-negative Staphylococcus sp isolated from milk samples from the refrigeration tank. To evaluate the efficiency of the pre-dipping, 12 animals were chosen and randomly divided into 3 groups. Each group received a treatment regarding the sanitation of the teats before the milking: no sanitation, sanitation using water followed by disposable paper towel drying and pre-dipping using iodine followed by disposable paper towel drying. To evaluate the sanitation efficiency of the mechanical milking machine s teatcups, were collected samples from them before the milking, after use on an animal, after use on two animals and after use on three animals. A participatory survey was held with a group of students from Family Farming, during which was also held a mini course named Good Practices on Milking , with theoretical and practical classes. During the practical classes, the students collected material from diverse spots of the milking room. It was applied a questionnaire referent to critical points on milking to evaluate the perception of the students before and after the mini course. Data from one question was statistically analyzed as to the frequency of choice of the answers. There were different perceptions, before and after, on all seven answers. On the experiment that tested the efficiency of the predipping there was significant difference as to the number of teats with Staphylococcus sp. and also positive Gram bacilli between treatments with no sanitation or with water sanitation and predipping. As to the milk bacterian count of the mammary quarters, there was significant difference between the treatments without sanitation and pre-dipping, although the treatment with only water kept statistically similar to the others. On the experiment that tested the sanitation efficiency of the mechanical milking teatcups, there was significant difference between the averages obtained before the milking, after milking of two and three cows, although the average obtained after the milking of one cow showed significant difference only if compared to the periods with three cows. As to the bacterian susceptibility to antimicrobials, it showed resistance to five, from the eight that were tested, in at least one sample, being them: amoxilicin+clavulanic acid, enrofloxacin, gentamicin, G penicillin and vancomycin, with the highest frequency being showed by the gentamicin