Dry-matter drift changes the load
When silage moisture moves and mixer kilograms stay fixed, nutrient delivery moves even if the written ration does not.
4 min read · 2026-09-17
In this note
- 30–35%
- 30–40%
Rain, face location, crop variation, and storage can change silage dry matter faster than a full laboratory panel returns. If the as-fed load stays fixed, cows receive a different amount of forage dry matter and the rest of the TMR shifts around it. The ticket can look unchanged while the consumed diet has already moved.
Penn State’s TMR-management work treats moisture as a delivery variable, not a footnote. Whole-plant corn silage often leaves the field near 30–35% DM and later sits in a broader 30–40% fermented window; a few points of DM drift change how many kilograms of water you are loading as if they were forage. The useful habit is to monitor silage DM routinely, update as-fed loading, and keep the laboratory nutrient profile on a dry-matter basis.
Check in the barn
What to check: When was bunker or pile DM last measured — this week, or last month’s lab bag? If DM dropped, did as-fed kilograms rise to hold forage dry matter? If DM rose, did the load get lighter? Walk the face and the mixer sheet on the same day.
Sister notes on this universe cover compare-dry-matter-not-water and the-lab-cannot-fix-the-sample. The physically-effective-fiber universe’s water-is-a-fiber-plasticizer and the-mixer-and-push-up-are-part-of-the-ration notes pick up how moisture also changes mixing damage and bunk delivery. Educational only — not a diagnosis, prescription, or ration formula.
Keep reading
View the networkNext
Compare the feed, not the water
As-fed columns answer loading questions; dry-matter columns answer nutrient-concentration questions.
Sister note · 4 min
Home plate: Rumen · The feed composition map · Water & dry matter
- Water & dry matterFirst splitPlaced here
- The laboratory cannot fix the sampleA precise analysis of one biased handful is still a poor estimate of the feed the herd is eating.Sister note
- A number without a unit is not a resultPercent, ppm, mg/kg, Mcal/lb, and Mcal/kg can turn the same digits into very different decisions.Same sheet
Mark size is the kind. Color is the atlas area.
- Focus
- Field note
- Rumen
Sources
- Understanding your forage test results — Oregon State University Extension
- TMR Management – Ensuring Formulated Rations Make it to the Bunk — Penn State Extension
- Nutrient Requirements of Dairy Cattle, 8th revised edition — NASEM (2021)
