Dry Matter vs. As-Fed Basis

Dry Matter vs. As-Fed Important concept in feed analysis Expression of nutrient content or feed amount on a "dry matter" or "as-fed" basis

All feeds contain water, some more than others Consider: Alfalfa pasture = 80.2% water Alfalfa hay = 9.5% water Dry Matter vs. As-Fed

When comparing the nutritional value of feeds, It must be done on a dry matter basis to be valid Dry Matter vs. As-Fed

As-Fed – as normally fed to animals Contains water Dry matter – does not contain water Dry Matter vs. As-Fed

DM content of a feed is the most important component because it contains almost all of the nutrients DM in a feed is: % dry matter = 100 – % water Dry Matter vs. As-Fed

Alfalfa pasture = 80.2% water DM = 100 – 80.2% = 19.8% Alfalfa hay = 9.5% water DM = 100 – 9.5% = 90.5% Dry Matter vs. As-Fed

Compare protein content of the alfalfa pasture and alfalfa hay On an as-fed basis, alfalfa hay appears to contain more protein 19.0% vs. 4.1% Dry Matter vs. As-Fed

On a dry matter basis, however, the hay and pasture are very similar 21.0% vs. 20.7% The as-fed protein comparison is misleading Dry Matter vs. As-Fed

Concentration (%, Mcal/kg) Start with As-Fed Basis of Nutrients (The “pie” represents nutrients in a feed)

Concentration (%, Mcal/kg) Convert to DM by removing water

Concentration (%, Mcal/kg) Notice how nutrient %’s go up (The “pie” represents nutrients in a feed)

As-Fed to DM Nutrient % gets BIGGER (Because water is removed) DM to as-fed Nutrient % gets smaller (Because water is added back in) For A Nutrient Concentration

Feed Amount (g, lb, etc.) As-Fed Basis Weight = 5 lb (Contains water)

Feed Amount (g, lb, etc.) Dry Matter Basis Weight = < 5 lb (Water removed)

As-Fed to DM Feed amount gets smaller (Because water is removed) DM to as-fed Feed amount gets BIGGER (Because water is added back in) For A Feed Amount