Summer Mastitis Flare-ups

Dairy Pipeline: August 1999

Gerald M. (Jerry) Jones
Extension Dairy Scientist, Milk Quality and Milking Management
Virginia Tech
(540) 231-4764
gmjones@vt.edu

Have you had an increase in the number of cows showing clinical mastitis during the last several months or has your DHI or bulk tank somatic cell count increased? The Southeast generally has higher somatic cell counts during the summer compared to other regions of the U.S. Sometimes it can be so severe that it results in a mammary secretion containing thick, foul-smelling pus and the loss of the affected quarter. Dry cows and heifers also can be affected or could be the source. Other possible sources may include: flies, damaged teat ends which may carry the bacteria Arcanobacterium pyogenes (used to be called Actinomyces) or Steptococcus dysgalactiae, shade trees under which cows congregate, streams, ponds, or wet bedding. Practices which may help control this mastitis include: avoiding damp, low-lying pastures (guess that's not a problem this year!), clean and dry calving areas, suckling among calves, and fly control. In addition to spreading infections from teats to teats and cows to cows, flies cause cows to bunch up and may augment heat stress. Fly control programs should incorporate: weekly clean-out of calf pens, hutches and box stalls; minimizing accumulated feed by feeding smaller amounts, more often, during cooler times of day; preventing manure accumulation, especially longer than one week; ear tags, bolus, or feed additives; pour-on sprays or dusts, and back rubbers. Make sure that any product applied on lactating cows is approved for use on dairy cattle.

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