Glossary · Feed
Total Mixed Ration (TMR)
A complete dairy ration where forages, grains, and supplements are blended into one feed before delivery to the bunk.
Total mixed ration (TMR) is the dominant feeding system on US dairies. All of a cow’s daily feed — forages, grains, protein supplements, minerals, vitamins — is mixed together in a TMR mixer wagon and delivered to the bunk as a single, homogeneous ration.
The advantages of TMR feeding over component feeding:
- Every bite the same. Cows can’t selectively eat the high-energy components and skip the fiber, which keeps rumen function stable.
- Easier to formulate. A nutritionist designs a single recipe rather than scheduling multiple feed deliveries.
- Less labor. One mix, one delivery, multiple times per day.
TMR effectiveness depends on three things:
- Mix accuracy. Loading errors or worn mixer components produce inconsistent rations.
- Mix duration. Over-mixing pulverizes forage and reduces physically effective fiber. Under-mixing leaves clumps.
- Sorting prevention. Cows will sort fines from longs if particle distribution is wrong. Particle separator (PSPS) data is the standard check.
TMR consistency audits — comparing the recipe to the delivered ration to the actual ration cows ate — are one of the highest-ROI nutrition interventions on a dairy. Most consistency problems are invisible without measurement.