Subclinical mastitis caused by staphylococcus aureus: Analysis cost benefit of antibiotic therapy in lactating cows

The cost benefit analysis of treatment of bovine subclinical mastitis caused by S. aureus was evaluated. Two hundred and seventy udder quarters with subclinical mastitis and healthy were selected in four groups, in conformity to lactational stage and with the treatment or not. Group 1 included treated animals 10 to 60 days in milk; group 2 included treated animals 61 days in milk until two months before the end of lactation; group 3 included animals not treated 10 to 60 days in milk; group 4 included animals not treated from 61 days in milk until two months before the end of lactation. Treatment with gentamicin (150 mg) was accomplished by intramammary doses, once a day, after sensitivity tests. The mammary quarters were evaluated after 30 days again. The costs with the treatment were calculated considering a S. aureus prevalence of 5%, expenses with antibiotic, loss in milk, tests of sensitivity and workload. There was loss of income of 2% and 14% in the groups 1 and 2, respectively, when compared with the incomes before treatment. In such case, the treatment of bovine subclinical mastitis by S. aureus in the lactation was economically not practicable.