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Nutrition Terms – “Alphabet Soup”
Often, nutritionists use terms such as NDF, ADIN and net energy when discussing forage test analyses. What do all of these terms mean? Read on and soon you will understand the significance of these terms and why the results are important to your production.
As Sampled Basis: The concentration of nutrients including all of the water in a forage/feed sample (fresh grass for example). Fresh grass has a high concentration of water and the grass will have a lower nutrient percentage as they are "diluted" in the water. This does not mean that fresh forage is bad. Rather, the best way to compare nutrients is to use the “dry matter basis” (below) as all the water is removed.
Dry Matter Basis: The only way to compare nutrients. Analysis of the forage nutrient concentrations after all water is removed (laboratory dried). This allows forage comparisons to be done without affecting the nutrient percentages. Recall as water is removed, the nutrients will be "concentrated".
Crude Protein (CP): A measure of all feed compounds containing nitrogen including protein and non-protein nitrogen (ammonia, nitrogen salts and urea). This value does not give any indication of protein quality. Shoe leather has a crude protein value of about 25-50%, but does it have any digestible protein? (no).
Digestible Protein (DP): An estimate of the protein percentage that the animal can digest (includes soluble and bypass protein). Shoe leather has a digestible protein level of less than 1%.
Soluble Protein (or Rumen Degradable Protein): Protein percentage that is digested in the rumen by bacteria and protozoa (microbes). If soluble protein is too high (high protein clover for example), protein is poorly utilized by the rumen and provides a very high protein to the simple stomach (C3). This can cause intestinal ulcers and/or scours (diarrhea) in alpacas.
Undegradable Intake Protein (UIP): Also known as bypass protein, this is the protein percentage that flows through the rumen into the camelid simple stomach (C3). Normally UIP is a very small amount in good forages.
Acid Detergent Insoluble Nitrogen (ADIN): Crude protein that is physically bound to fiber and is completely indigestible. This value will be high if there has been significant and inappropriate forage/feed heating (hay stored in a hot barn). A value of greater than 10% will cause a reduction in the digestible crude protein value of the feed.
Macro-Minerals: Forage/feed minerals in relatively high concentrations including calcium, phosphorous, sodium, magnesium and potassium.
Micro-Minerals: Forage/feed minerals in relatively low concentrations such as copper, iron, manganese, selenium, zinc, molybdenum, etc.
Neutral Detergent Fiber (NDF): The structural components of the feed cell wall material. This provides the essential dietary bulk and is a major determinant in how much forage volume the ruminant consumes on a daily basis.
Acid Detergent Fiber (ADF): Measures the feed fiber fraction containing cellulose and lignin (the least digestible “woody” parts of the plant). Lignin and other indigestible carbohydrates are found in forages that are cut too late in the growth stage. High ADF levels mean low digestibility while low ADF means higher energy and digestibility of the forage/feed.
Metabolizable Energy (ME, Mcal/kg): Gross energy of the feed minus the energy lost through excretions (urine, sweat, gases and feces). This value includes the energy used for digestion and metabolism of nutrients into tissues.
Digestible Energy (DE, Mcal/kg): Describes the gross energy minus the energy lost in the feces. This is an estimated value based on ADF.
Nitrates: The form of nitrogen that plant roots take up from the soil and forms the digestible basis of plant leaves.
Net Energy for Maintenance (NEm, Mcal/kg): Portion of ME available for basic physiological maintenance (not growth, pregnancy or lactation).
Net Energy for Gain (NEg, Mcal/kg): Portion of the ME available for body weight gain (largely protein) including pregnancy.
Net Energy for Lactation (NEL, Mcal/kg): Portion of the ME available for lactation (forming milk).
Non-Structural Carbohydrates (NSC): Simple carbohydrate energy sources such as simple sugars (molasses for example) and starches. Excess can be a problem in alpacas (gassy rumen).
Total Digestible Nutrients (TDN): Describes the percentage of total energy sources (fiber, protein, sugars, starches and fat) in a feed not excreted in feces and urine. In alpacas, should be 55-65%.
Relative Feed Value (RFV): Evaluates legumes and forage quality based on the factors of digestibility and intake. The higher the RFV, the better.
Nutrition Overview
Nutrition Terms
Transfer Factor
Problems with Rye
Bermudagrass
Orchardgrass Choices
Alfalfa Forage
Nutrition Issues
Copper a Micronutrient