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Commodities: Field Crops: Forages

Common Terms Used in Animal Feeding and Nutrition

Glossary: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

M

Macro-minerals: or trace minerals, are present in the animal body tissues in extremely low concentrations. Hence they are nutrients, required in small amounts, generally in milligram (mg) or microgram (µg) amounts per head per day, but play critically important roles in animal nutrition. The seven macro-minerals essential to animals are (the mineral names are followed by their chemical symbols): calcium (Ca), phosphorus (P), sodium (Na), magnesium (Mg), potassium (K), sulphur (S), chlorine (Cl).

Megacalorie (Mcal): The quantity of energy available in a feed or the amount of energy required for an animal to perform a specific function is most often expressed as a unit of heat, the smallest of this unit is called “calorie”. Because a calorie is too small to express the energy for practical purposes, the energy content of feed is most often expressed in a larger unit called “megacalorie”; one megacalorie is one million times larger than one “calorie”.

  • 1,000 Calorie (cal) = 1 Kilocalorie (Kcal)
  • 1,000 Kcal = 1 Megacalorie (Mcal)
  • Therefore, 1 Mcal = 106 cal

Metabolizable Energy (ME): Metabolizable energy equals the gross feed energy minus the energy lost in the feces, urine and gaseous product of digestion:

  • ME = GE – FE (energy in feces) – (energy in urine) – (energy gases)
  • ME = DE (digestible energy) – (energy in urine) – (energy in gases)
  • Because, DE = GE – FE

Measuring the amounts of energy lost in gaseous form and in the urine is more difficult than measuring that lost in feces. Therefore ME value of individual feeds is rarely measured as opposed to their DE. However, when ME values are needed conversion formulas are often used by nutritionists. A commonly used formula to estimate ME in beef feedstuffs is: ME = 0.82 × DE.

Micro-minerals: or trace minerals, are present in the animal body tissues in extremely low concentrations. Hence they are nutrients, required in small amounts, generally in milligram (mg) or microgram (µg) amounts per head per day, but play critically important roles in animal nutrition. There are 10 micro-minerals recognized in animal nutrition: iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), cobalt (Co), iodine (I), chromium (Cr), molybdenum (Mo) and nickel (Ni). In Georgia, only three of the micro-minerals (copper, zinc and selenium) are likely to be deficient in grazing animal diets. However, copper is particularly toxic in sheep and selenium can also be toxic. Deficiencies and toxic levels are quite regional.

Milligram per kilogram (mg/kg): a common unit of concentration representing how many mg of the target substance (i.e., the substance analyzed in the laboratory) present in one kg of the sample. Since one mg is one-millionth of a kg (or 1 kg is 1 million mg), mg/kg is equivalent to parts per million (ppm). For example, a 20 mg/kg calcium concentration in a feed sample is equal to 20 ppm calcium.

Minerals: In feed analysis, this refers to inorganic feed elements essential for life.

Mycotoxins: Substances that are toxic to animals produced on plants by fungi, particularly during weather stress during the growing or harvest seasons or during feed storage (e.g., vomitoxin, zearalenone, aflatoxin and T-2, etc.).