The effect of udder infection on the bacterial flora of the bulk milk of ten dairy herds.

The significance of udder infection as a factor increasing the bacterial count of herd bulk milk was measured monthly for one year in ten dairy herds in Southern England. Staphylococcus aureus or mastitis streptococci were detected in 86% of samples, usually in numbers between 1000 and 10 000 c.f.u./ml of milk. However, in 8 and 2% of samples respectively greater than 20 000 or 100 000 c.f.u. of mastitis pathogens/ml of milk were detected. This occurred most commonly in the herds with a high incidence of Streptococcus uberis mastitis. The total bacterial counts of the herds' milks varied between 13 960 and 46 230 c.f.u./ml in the winter and between 6510 and 63 000 c.f.u./ml in the summer. No correlation was found between bacteriological quality of herd milk and the cleanliness of the milking machine and pipeline as assessed by plant rinses.

Corynebacterium pyogenes mastitis among heifer calves.

In August 1975 an outbreak of C pyogenes mastitis occurred involving 18 heifer calves at the National Institute for Research in Dairying. This paper describes the outbreak which affected animals varying in age from five to 22 months. Fourteen of the cases (77%) were among calves less than 10 months old. The advisability of using fly control measures among young stock in the summer months is discussed.