Analysis of DHIA records indicates that the single most important factor accounting for milk production variation among herds is somatic cell counts.
Most dairymen can find the cows with clinical mastitis.
Clinical cows have LS 7 or greater. Subclinical mastitis is often considered as LS of approximately 3-7. The only practical way to measure this hidden mastitis is with DHIA somatic cell counting monthly. Cows with the lowest LS in early lactation are less likely to experience increased LS later as compared to cows with cell counts greater than 100,000. 1985 Cows with linear scores of 4 or greater for the first time are considered new infections and all cows with 5 or greater are problems.