Changes

==What is Energy?==

==What is Energy?==

Energy is not a nutrient specifically, but is derived from macronutrients found in foods (protein, fat, and carbohydrate). Energy in food is usually considered at 3 different levels.  

'''Energy is not a nutrient specifically, but is derived from macronutrients found in foods''' ([[Protein Overview - Nutrition|protein]], [[Fat Overview - Nutrition|fat]], and [[Carbohydrates Overview - Nutrition|carbohydrate]]). Energy in food is usually considered at 3 different levels.  

#Gross energy (GE): this is the total (thermic) energy in the foods released by complete oxidation. Although a food may have a high GE content, it may be indigestible and therefore unavailable to the animal.  

#'''Gross energy (GE):''' This is the total (thermic) energy in the foods released by complete oxidation. Although a food may have a high GE content, it may be indigestible and therefore unavailable to the animal.  

#Digestible energy (DE) is the amount of energy which is digested and absorbed by the animal, and this is equivalent to GE minus faecal losses. Not all of the DE is available to the animal; some is lost in the urine as energy is metabolised by tissues and cells.  

#'''Digestible energy (DE):''' This is the amount of energy which is digested and absorbed by the animal, and this is equivalent to GE minus faecal losses. Not all of the DE is available to the animal; some is lost in the urine as energy is metabolised by tissues and cells.  

#Food energy that is utilised by the tissues is referred to as metabolisable energy (ME) and it is calculated from DE minus urinary losses of energy. This is the most meaningful measure of food energy as it represents energy that is truly available to the animal to use.  

#'''Metabolisable energy (ME):''': Is food energy that is utilised by the tissues and it is calculated from DE minus urinary losses of energy. This is the most meaningful measure of food energy as it represents energy that is truly available to the animal to use.  

The designated SI unit of energy is the joule (J), with kiloJoules (kJ), or kilocalories (kcal) in the United Stated, used in animal nutrition.  1 calorie=4.184 joule

The designated SI unit of energy is the joule (J), with kiloJoules (kJ), or kilocalories (kcal) in the United Stated, used in animal nutrition.   

'''1 calorie = 4.184 joule'''

==Why is it Important?==

==Why is it Important?==