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% waterAlfalfa 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% waterDM = 100 – 80.2% = 19.8%

• Alfalfa hay = 9.5% waterDM = 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)

10

70

1 4 15

% As-Fed Basis

ProteinEnergyCalciumMineralsWater

Start with As-Fed Basis of Nutrients

(The “pie” represents nutrients in a feed)

Concentration (%, Mcal/kg)

10

70

1 415

% As-Fed Basis

ProteinEnergyCalciumMineralsWater

Convert to DM by removing water

Concentration (%, Mcal/kg)

12

82

1.24.8 % Dry Matter Basis

ProteinEnergyCalciumMinerals

Notice how nutrient %’s go up

(The “pie” represents nutrients in a feed)

• As-Fed to DMNutrient % gets BIGGER(Because water is removed)

• DM to as-fedNutrient % 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 DMFeed amount gets smaller(Because water is removed)

• DM to as-fedFeed amount gets BIGGER(Because water is added back in)

For A Feed Amount