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Forage Quality Definitions

• Crude Protein (CP)
• Insoluble Crude Protein (ICP)
• Adjusted Crude Protein (ACP)
• Acid Detergent Fiber (ADF)
• Neutral Detergent Fiber (NDF)
• Dry Matter (DM)
• Digestible Dry Matter (DDM)
• Dry Matter Intake (DMI)
• Digestible Dry Matter Intake (DDMI)
• Relative Feed Value (RFV)
• Legume Quality Standards

Crude Protein (CP) gives an indication of the ability of the feed to meet livestock protein requirements. It is a mixture of true protein and non-protein nitrogen, and also includes insoluble protein. In general, a high Crude Protein (CP) level is desirable and usually obtained by harvesting at an early stage of growth. Legumes contain higher levels of CP than do grasses.

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Insoluble Crude Protein (ICP) is actually acid detergent insoluble nitrogen. It is an indicator of the amount of heating that has taken place in storage and a fraction of Crude Protein that is indigestible to livestock. A low ICP is desirable.

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Adjusted Crude Protein (ACP) is really the amount of Crude Protein that is available to the livestock for digestion. Adjusted Crude Protein= Crude Protein - Insoluble Crude Protein. The ICP to CP Ratio should be less than 10 if harvest and storage practices were correct. A high ICP/CP Ratio may occur when cutting is delayed, hay is baled too wet, or haylage is stored too dry, resulting in excessive heating that can cause significant heat damage. When the ICP/CP Ratio is 15 or more, ACP should be used to balance rations.

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Acid Detergent Fiber (ADF) represents the highly indigestible fraction of the forage such as cellulose, Lignin, Silica, and insoluble Nitrogen compounds. As forage plants mature, ADF increase and digestibility of the forage decreases. Thus, a low percent ADF is most desirable.

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Neutral Detergent Fiber (NDF) is composed mainly of the cell wall fraction of the forage and includes hemicellulose and the ADF components. The NDF Fraction of forage is only partially digestible and is inversely related to forage intake. In other words, the higher percentage of NDF, the less of the forage the animal we eat. Therefore, a low NDF is desirable.

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Dry Matter (DM) is the percentage of the forage that is not water. If a forage is 55% DM, then it has 45% water. (100-55=45) Rations are balanced on a Dry Matter basis.

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Digestible Dry Matter (DDM) is an estimate of the percentage of the forage that is digestible as determined from ADF concentration. DDM is used to estimate the energy value of the forage. The lower the ADF, the higher the DDM will be.

Dry Matter Intake (DMI) is based on NDF Concentration and is an estimate of the amount of forage an animal will consume.

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Digestible Dry Matter Intake (DDMI) is an estimate of the DDM that the animal will consume. Intake of digestible energy can also be estimated by DDMI.

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Relative Feed Value (RFV) is an index calculated from forage analysis which combines ADF (digestibility) and NDF (intake) nutritional factors to arrive at one number to measure and compare forage quality. The higher the RFV, the higher the forage quality.

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Legume Quality Standards

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