A high somatic cell count, or SCC, indicates that a herd has a high prevalence of subclinical mastitis. Wisconsin dairies with serious subclinical mastitis problems are up to seven times more likely to have antibiotic residues in their milk than producers with herds that have a low incidence of mastitis, according to the study. The pasteurized milk ordinance prohibits antibiotic residues in milk primarily to protect consumers who may have an allergic reaction to the compounds. Treating mastitis is the most common use of antibiotics on dairy farms. Producers know that reducing the incidence of subclinical mastitis leads to higher milk production and valuable premiums for milk quality.
Most dairy farms do an excellent job of preventing antibiotic residues in milk.
She leads educational programs to help farmers improve milk quality. To look for a relationship between SCC and antibiotic residues, Ruegg and dairy scientist Tom Tabone obtained data on milk tests from the Wisconsin Department of Agriculture, Trade and Consumer Protection. Their study analyzed more than 805,000 milk tests on Wisconsin's grade A dairy farms. The tests of SCC levels from bulk tanks and antibiotic residues covered the period from January 1995 until December 1998. For comparison, the national herd average SCC was 300,000 and the state average was 310,000 last year.