As fed: how much of a feed or nutrient is fed to livestock, including the moisture present in the feed.
Dry Matter (DM): the quantity of a feed or nutrient fed to livestock after water is removed. All the nutrients in a feed are contained in its dry matter, and feeds with higher moisture content must be consumed at greater quantities in order for dry matter requirements to be met.
Dry Matter Intake (DMI): the predicted intake of DM
Total DMI (TDMI): the predicted maximum intake and is the main constraint in formulating a ration. TDMI varies with animal weight, requirements above maintenance such as production, growth and gestation, and age. TDMI is regulated by both physiological factors (negative feedback of end products of digestion and metabolism) and physical factors (fiber content, capacity of the digestive tract, and rates of fermentation and passage).
Roughage DMI (RDMI): the predicted maximum forage intake. The difference between TDMI and RDMI is met by supplements.
Total DMI = Roughage DMI + Supplements
Crude Fat (CF): Also referred to as ether extraction, a dried and ground feed sample is extracted with diethyl ether. Diethyl ether dissolves fats and fat soluble components of a feed, and after extraction the ether is evaporated. The end product is weighed, and this value is referred to as crude fat.
Crude Protein (CP): total nitrogen content of the feed x6.25. CP measures true protein and non-protein nitrogen. In ruminants, CP is used by bacteria in rumen for aid with digestion.
Rumen Degradable Intake Protein (DIP): the protein from the diet that is broken down and converted into microbial protein through the use of NH3. The degradability of a protein is determined by solubility and length of time in the rumen. It is increased by fermentation and decreased by heat treatment.
Non-Protein Nitrogen (NPN): A subcategory of DIPs found in pasture, silage, and hay. Ensiling increases NPN quantities. Ruminants are the only species capable of converting NPN to true protein
True Protein: degraded in the rumen to amino acids and then NH3. Microbes in rumen use NH3 to make microbial protein.
Rumen Undegradable Intake Protein (UIP): also referred to as Rumen Bypass Protein. Protein that has a slow rate of digestibility and bypasses digestion in the rumen because it isn’t used by rumen microbes. UIP gets metabolized in the lower G.I. tract or is passed in the manure. Microbial protein can only support a finite level of production, and as production requirements increase the need for bypass protein increases.
Crude Fiber (CF): from the diet, it is a measure of the fraction resistant to degradation in acid and alkali. This measure underestimates fiber content.
Acid Detergent Fiber (ADF): measures cellulose and lignin contents of a plant. ADF is related to the measure of digestibility of forage, where higher ADF is related to lower digestibility and low levels of ADF are therefore desirable.
Neutral Detergent Fiber (NDF): measures cellulose, lignin, and hemicellulose (total fiber components) contents of a plant. Measures of NDF are used to predict feed intake, where high levels of NDF decrease intake. NDF is negatively associated with dry matter intake (DMI) and positively associated with ruminating and salivation.
Energy: not technically a nutrient, but still a very important part of an animal’s diet. Energy from feed is derived from digestion, absorption, and metabolism. The main source of energy is CHOs, however it can also be derived from lipids.
Digestible Energy (DE): The energy value obtained by subracting the energy passed in the faeces from the gross energy.
Net Energy (NE): calculated from total digestible nutrients (TDN)
Net Energy for Maintenance (NEM): a measure of the net energy required for an animal at equilibrium.
Net Energy for Gain/Growth (NEG): a measure of the net energy required in addition to maintenance for gain/growth.
Net Energy for Lactation (NEL): a measure of the net energy required during lactation. NEL is the only net energy value required for lactating cows.
Ash: a measure of the total mineral content of a type of forage, representing 3-12% of DM. It is determined by burning the organic matter and weighing the residue. An ash value above 10% in grasses and 14% in legumes usually indicates contamination of forage by minerals in the soil.
Micro minerals: those that are required in smaller amounts (i.e. Manganese (Mn), Iron (Fe), Copper (Cu), Zinc (Zn), and Molybdenum (Mo))
Macro minerals: those that are required in larger amounts (i.e. Calcium (Ca), Phosphorus (P), Potassium (K), Magnesium (Mg), and Sulphur (S))
Dietary Cation-Anion Balance (DCAB): measured in mEq/kg, DCAB is the difference between the cation and anion content of an animal’s diet. Cations produce a more alkaline metabolic state and anions produce a more acidic metabolic state. Determining the DCAB can help to prevent different metabolic diseases, such as milk fever in dairy cattle.
Starch: the energy store for plants, starch contains the highest proportion of CHOs in a seed; derived from non cell wall materials.
Relative Feed Quality: a value that combines NDF (predicted intake) and ADF (predicted digestibility) values of forage. It is an accurate predictor of forage value.
References:
Agrifood Labs Feed Analysis Terminology
Dietary Cation-Anion Difference, OMAFRA
Dairy Nutrition Primer Notes, Dr. K. Lissemore
Feeds and Feeding for Ruminants and Horses (lecture and notes), Dr. K. Lissemore