The difference in hereditary susceptibility to three mastitis agents between two daughter groups.

Daughter groups of two sires A and Z were kept under equal conditions during 3 lactations. Experimental infections with mastitis agents gave different responses in both groups. The evident difference in susceptibility to mastitis between the A- and Z-daughters is based upon genetic differences. The results of this experiment indicate the possibility of selecting AI-bulls with respect to mastitis in descent and offspring. In this experiment staphylococci were less pathogenic than Str. agalactiae and Str. dysgalactiae. The most severe reactions were produced by the infections with Str. dysgalactiae.