Herds with Low Somatic Cell Counts

Dairy Pipeline: September 1998

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

Scientists from the Netherlands examined the relationship between herd management practices and somatic cell counts in bulk milk (BMSCC). In Europe, bulk tank somatic cell counts above 400,000 are unacceptable. Three categories of dairy herds were selected, each consisting of 100 herds: <150,000 BMSCC, 151-250,000 BMSCC, and 251-400,000. The BMSCC was determined 13 times/yr. The low BMSCC herds both before and during the study (n=73) had a geometric mean BMSCC of 114,000 (range 62,000 to 150,000). Medium BMSCC herds averaged 194,000 (151-250,000) and high herds averaged 310,000 (253-401,000). As BMSCC decreased, milk production increased. Most important factors associated with decreasing BMSCC were: postmilking teat disinfection, duration of treatment of clinical mastitis cases, and no drying after wet premilking treatment. Additional management practices included stricter attention to dry cow treatment, hygiene, and nutrition. Postmilking teat disinfection and dry cow therapy were practiced most frequently in herds with low BMSCC. Also, these herds paid more attention to hygiene and detail. Cubicles, drinking buckets, and cows all were cleaner and low BMSCC herds more often clipped hair of all cows every year. Moisture of bedding for lactating cows and in maternity pens was lower for herds with low BMSCC. Better hygiene decreases exposure to environmental pathogens in cubicles and calving parlor and decreases transmission of contagious pathogens during milking. Supplementation of the diet with minerals, especially in summer when cows grazed pasture, was found to be important. Other studies have suggested that imbalances in dietary selenium, copper, zinc, Vitamin E, and Vitamin A or beta-carotene decrease resistance to disease.

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