CowdemyRumenFIG. 05Foundation10 min
The feed composition map
Separate water from dry matter, ash from organic matter, and the major nutrient families before chasing individual acronyms.
ShareThe feed composition map
Spot it
MeaningThe amount of nutrient dry matter delivered per cow has changed.
Next checkRecalculate as-fed loading from the current dry-matter result.
Field notes on this focus
- Note 01Compare the feed, not the waterAs-fed columns answer loading questions; dry-matter columns answer nutrient-concentration questions.4 min · 2026-09-17
- Note 02Dry-matter drift changes the loadWhen silage moisture moves and mixer kilograms stay fixed, nutrient delivery moves even if the written ration does not.4 min · 2026-09-17
Also touches this focus
- Note 01Chemical fiber is not effective fiberGrinding can leave the NDF percentage intact while removing much of the particle structure that stimulates chewing.4 min · 2026-09-17
- Note 02The laboratory cannot fix the sampleA precise analysis of one biased handful is still a poor estimate of the feed the herd is eating.4 min · 2026-09-17
- Note 03Chop length is not peNDFChop length is a harvester setting; peNDF is the fiber structure that actually reaches the rumen after moisture, processing, mixing, and sorting.3 min · 2026-09-10
- Note 04Water is a fiber plasticizerForage dry matter changes how the TMR mixes and how the particle box reads — even when chop length matches a drier day.3 min · 2026-09-10
Sources
- Nutrient Requirements of Dairy Cattle, 8th revised edition — NASEM (2021)
- Understanding and Using a Feed Analysis Report — University of Nebraska–Lincoln Extension
- Understanding your forage test results — Oregon State University Extension
- Interpreting Feed Analysis — University of New Hampshire Extension
Plate credit
Stomach figure adapted from the public-domain 1905 plate Interior of a cow (The Household Physician; Wikimedia Commons) and standard ruminant-stomach teaching figures. Educational only.
Not a veterinary diagnosis, prescription, or ration formula.