May 04, 2016 · Low Peaks. Evaluate the herd for a high incidence of subclinical or clinical mastitis. Check individual milk samples from all milking cows using CMT or DHIA-SCC. The average somatic cell count should be under 300,000. In the whole herd, 10% or less of the cows should have a positive 2 or higher CMT on a composite of four quarters or positive 3