Major changes in milk by mastitis causative agents in goat herd from the states of Minas Gerais and Rio de Janeiro, Brazil

Abstract

Goat mastitis causes significant economic losses due to the discarding of milk, costs of drugs and veterinary care, reducing the quantity and quality of milk and dairy products. In this study, 129 raw milk samples from 11 goat farms were investigated by the Tamis test, California mastitis test (CMT), bacteriological exam, presence of Mycoplasma spp. and physicochemical parameters. Seven (4.6%) and four samples (3.1%) were positive by CMT and Tamis test respectively. Bacteriological exam was positive from 57.4% of samples and coagulase-negative Staphylococcus was the most frequent bacteria isolated showing 56% of the strains resistant to penicillin and no resistance to gentamicin. Negative results were obtained from traditional culture as well as by PCR for Mycoplasma spp. The diagnosis of mastitis, the bacteriological exam and the CMT results differed significantly and no association was observed (chi squared, p < 0.05). Fat was the constituent with more variations and 63.4% of the herds did not meet the minimum requirement according to Brazilian government criteria for this constituent. There was no significant association between mastitis and the physicochemical parameters (t-Student, p > 0.05). The physicochemical parameters differed significantly (ANOVA, Tukey-Kramer, p < 0.05) among the herds. These results indicate the need to associate microbiological exam when the CMT is used for the diagnosis of goat mastitis.