Somatic Cell Count (SCC) to Linear Score Calculator & Milk Loss

How it works

Linear score (SCS) = log₂(SCC ÷ 100,000) + 3 · Milk loss per lactation ≈ (SCS − 2) × 200 lb (first lactation) or × 400 lb (later lactations), for SCS above 2

Dairy Herd Improvement (DHI) records convert somatic cell counts to a 0–9 linear score because the score relates linearly to lost milk: every doubling of the cell count adds one point. A score of 4 corresponds to 200,000 cells/mL, the level above which subclinical mastitis is likely. The National Mastitis Council fact sheet estimates that each point above 2 costs about 200 lb (91 kg) of milk in first-lactation cows and 400 lb (181 kg) in older cows over a lactation.

Worked example

A mature cow with 200,000 cells/mL: SCS = log₂(200,000 ÷ 100,000) + 3 = 1 + 3 = 4.0 — "Borderline — monitor this cow". She is 2 points above 2, so the expected loss is 2 × 400 lb = 800 lb, or about 363 kg of milk over the lactation (1.2 kg/day).

Sources: National Mastitis Council — The value and use of DHI somatic cell count (SCS table and milk loss) · University of Nebraska–Lincoln Extension — How to interpret the DHIA-520 somatic cell count profile

Frequently asked questions