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Dry Matter Basis
Values in this column give the nutrient information with the water removed. This allows comparisons to be made between forages. It is the best indication of nutrient value because animals tend to eat on a dry matter basis. Unless forages get very wet, animals will eat more of a wetter forage until they have eaten the same amount of dry matter. Conversion to the as received or as fed value can be made by multiplying the value by the percent dry matter.
As Received
All values under this heading show the content of the nutrients with the moisture in the forage included. Because of the dilution with water, the values will be lower than the dry basis column.
Crude Protein (CP)
Crude protein will include both true protein and non-protein nitrogen. Animals can utilize both types to some degree. Crude protein values give no indication if heat damage has occurred which may alter protein availability. Generally, high crude protein is desirable.
Acid Detergent Fiber (ADF)
This value refers to the cell wall portions of the forage that are made up of cellulose and lignin. These values are important because they reflect the ability of an animal to digest the forage. As ADF increases, digestibility of a forage usually decreases.
Neutral Detergent Fiber (NDF)
The NDF value is the total cell wall which is comprised of the ADF fraction plus hemicellulose. Neutral detergent fiber values are important in ration formulation because they reflect the amount of forage the animal can consume. As NDF percentages increase, dry matter intake will generally decrease.
Calculated Values
These values are generated from equations that use other data from the analysis of the forage sample. There is no requirement that laboratories must use the same standardized formulas. This makes comparisons between laboratories difficult. Laboratories should be able to provide the source and accuracy of the formulas they use.
Relative Feed Value
Relative feed value is an index which combines the important nutritional factors of intake and digestibility. It has no units, but the index allows comparisons of legume, grass and legume-grass forages. A forage with ADF of 41 percent and NDF of 53 percent has an index of 100. Other forages can then be compared against this value. When a forage has a value above 100, it is not necessarily a superior quality forage. This is because the ADF and NDF values that generate the value of 100 are relatively high, thus the forage is not considered any better than average. As percent ADF and NDF decrease, the RFV will increase.
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