[Correlation between the degree of reaction to the rapid mastitis test and the changes in the chemical makeup and properties of bulk cow's milk].

Samples of trade cow milk from the milk combine in Stara Zagora were investigated using the quick mastitis tests "Sofia" and "Bernburg". It was established that 38% of the samples studied react positively (+). The samples reacting in a varying degree to the test were investigated for content of total protein, caseine, whey protein, lactose, chlorides, calcium and number of somatic cells. An electrophoretic separation of the caseine fractions was performed on acrylamide gel. The refraction number of milk serum was determined. No composition and property changes were observed in milk samples reacting positively to the test and having a cell content lower than 1 000 000/cm3. Changes of the protein components in favour of whey proteins were evident in milk samples having a positive reaction to the test as well as cell content higher than 1 000 000/cm3. The electrophoretic picture of caseine from milk samples reacting positively to the test and having higher than 1 000 000/cm3 cell content includes all caseine fractions typical for cow milk, but a reduction in the Ls and beta caseine fractions and an increase of kappa- and gamma fractions is observed.