Examination of problem mastitis herds in Ohio

4 problems can occur in a dairy herd which may cause the herd to be identified as a problem mastitis herd. These are (i) antibiotic residues present in bulk tank milk, (ii) high bacterial count, (iii) high leucocyte count, and (iv) increased number of serious clinical cases with deaths. Milk samples were taken from Ohio dairies during the period from Jan. to May 1975 and data are given for (i) and (ii): less than or equal to 0.45% of samples contained antibiotic residues; and less than or equal to 7.5% contained >100 000 bacteria/ml. To determine (iii), milk samples were screened using the Wisconsin Mastitis Test and if a high reading was recorded, the leucocyte count was confirmed using Direct Microscopic Somatic Cell Count. Between 1/4 and 1/3 of Ohio herds were experiencing quite high leucocyte counts. Measures are outlined to assist the dairyman in preventing (i)-(iv) which involves: checking the environment, milking machine function and milking technique; cow examination and dry cow therapy..