[Occurrence and etiology for subclinical mastitis in cows]

Studied were a total of 16,571 cows on 89 farms by means of the Bernburg test. Milk was sampled from the positively reacting quarters of the udder by taking 18,047 samples intended for bacteriologic investigation. The demonstration of mastitis streptococci was carried out on "TKT" agar Merk, of pathogenic staphylococci, hemolytic streptococci, and Corinebacteria--on dextrose agar Oxoid containing 7.5% citrated calf blood. The isolated hemolytic streptococcus bacteria from the two nutrient media were differentiated through the CAMP test as well as serologically by the precipitation agar gel and Difco sera. The pathogenicity of Staphylococcus bacteria, in addition through hemolysis, was tested by the use of plasma coagulase with citrated rabbit plasma. In 53.95% of the cases there were secretory lesions due to Sc. agalactiae (6.23%) to Sc. dysgalactiae (5.69%) to Sc. uberis (8.47%), to Staph. aureus (2.44%), to hemolytic streptococci of the C, G and L groups (0.28%), to Sc. viridans (0.03%), to Corynebacterium pyogenes (0.41%), and catarrhal mastitis (30.4%). Some of the causative agents, such as Sc. agalactiae, Staph. aureus, and others have proved of epidemiologic importance to humans.