Expert glossary
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ADF (acid detergent fiber): the portion of forage consisting primarily of cellulose and lignin. As ADF increases, the forage becomes less digestible. ADF increases with plant maturity.
Aerobic microorganisms: organisms that are living or metabolically active in the presence of oxygen.
Ambient temperature: the temperature of the surrounding air.
Anaerobic microorganisms: organisms that are living or metabolically active in the absence of oxygen.
Available protein: protein that is available for use by the animal. Difference between crude protein and unavailable (bound or insoluble) protein.
Bunk life: the length of time silage in the feed bunk can be exposed to air before it begins to spoil.
CP (crude protein): includes both true protein and non-protein hydrogen. CP value does not give any indication whether heat damage occurred, or how much protein is available.
DDM (digestible dry matter): an estimate of forage digestibility. As ADF increases, DDM decreases. DDM can be used as an estimate of energy in ration balancing.
DM (dry matter): the percent of forage that is not water. Percent moisture plus percent DM equals 100 percent.
DMI (dry matter intake): amount of dry matter an animal consumes. Frequently expressed as a percent of body weight.
DP (digestible protein): calculated value that is generally 70-72 percent of CP value. Does not give any indication of heat damage.
FCM (fat corrected milk): the milk market has established 3.5-4.0 percent butterfat as the usual basis for pricing. A price differential is applied to milk above or below this amount.
Fermentation: in silage, the utilization of plant sugars by microorganisms to produce organic acids.
Heterofermentation: fermentation in which acetic and lactic acids are produced.
Homofermentation: fermentation in which mainly lactic acid is produced. It quickly controls the fermentation and stabilizes silage.
LAB (lactic acid bacteria): bacteria that produce only lactic acid or a combination of lactic and acetic acids.
NDF (neutral detergent fiber): the total cell-wall fraction, which consists of ADF and hemicellulose. As ADF increases, DM intake decreases. NDF increases with plant maturity.
NEG (net energy for gain): energy content of forage available for growth. It is calculated from the ADF.
NEL (net energy for lactation): the energy content of forage available for milk production. It is calculated from the ADF.
Organic acid: acid formed from the fermentation of an organic substrate, such as lactic acid from plant sugars.
pH: the measure of acidity of a substance. pH values range from 0 to 14, with 7 representing neutrality, less than 7 is acidic, and greater than 7 is basic or alkaline.
Respiration: the process by which plants or bacteria utilize oxygen and plant sugars to form carbon dioxide, water, and heat.
RFV (relative feed value): an index that combines the important nutritional factors of intake and digestibility. RFV carries no units and is calculated from the ADF and NDF. As ADF and NDF decrease, RFV increases. This value allows comparisons of same-crop forages.
Substrate: the substance on which an enzyme acts or a living organism grows.
TDN (total digestible nutrients): an estimate of forage digestibility used for energy balancing. TDN is calculated from the ADF. As ADF increases, TDN decreases.
WSC (water-soluble carbohydrates): fermentable sugars in plants, such as glucose, sucrose, and starch.