Glossary · Production
Fat-Corrected Milk (FCM)
Milk production normalized to a standard 3.5% fat. The metric used to compare cows and herds with different fat contents.
Fat-corrected milk (FCM) is milk production normalized to a standard fat percentage — typically 3.5% FCM. It’s the metric used to compare production across cows or herds with different milk fat contents.
The most common formula:
3.5% FCM (lbs) = (0.4324 × milk lbs) + (16.216 × fat lbs)
For example, a cow producing 90 lbs of milk per day at 4.0% fat (3.6 lbs of fat) yields:
- 3.5% FCM = (0.4324 × 90) + (16.216 × 3.6) = 38.92 + 58.38 = 97.3 lbs FCM/day
FCM is the numerator in the feed efficiency ratio (FCM ÷ DMI), which is why it shows up so often in dairy management. Comparing herds, cows, or even feeding protocols across different fat percentages requires FCM — comparing raw milk lbs would mislead.
Some operations use 3.2% FCM or 4% FCM depending on local milk pricing systems. The principle is the same; only the standardization fat percentage changes.