Milk is the normal secretion of the mammary gland, practically free of colostrum and obtained by the complete milking of one or more healthy animals.
Mastitis is an inflammatory process of the mammary gland and it may cause alterations in the milk. The present work aimed to verify whether it is possible, by means of the counts of microorganism in the bulk raw milk in four selective
culture media, to establish a correlation with the occurrence of
mastitis and therefore, to monitor this disease in bovine dairy herds. The following selective
culture media were used: KF Streptococcus
Agar, Edwards
Agar, Baird-Parker
Agar, Blood
Agar plus
potassium tellurite. Spearman's correlation coefficient was calculated in order to compare the occurrence of
mastitis (percentage) in each herd with respective selective
culture media counts of microorganisms in bulk raw milk. Thirty-six possibilities were analysed (Tamis and CMT-positive rates were compared with the log-transformed count in four selective
culture media) and there was a negative correlation between Tamis 3 and the Baird-Parker
Agar plate count. The total results of microbiological tests showed that there were three correlations of the counts in selective
culture media. Fifty-two possibilities were analysed and there was a negative correlation between no-bacterial-growth
mastitis rates and log10 of KF Streptoccocus
Agar plate count and there were two positive correlations between
coagulase-positive staphylococci and log10 of Baird-Parker
Agar plate count and Blood
Agar plus
potassium tellurite plate count.