There are three ways in which energy is expressed in relation to dog and cat food:
Gross Energy (GE) measured by the heat produced from burning a food.
Digestible Energy (DE) determined by feeding trials, it is the difference between the GE in a food, and the GE lost in feces.
Metabolizable Energy (ME) a measurement of actual utilization, it is the difference between the GE in the food, and GE lost in the feces and the urine. This may be determined using a calculation, and may be expressed as ME=X kcals (kilocalories or calories) per cup on packaging. This is the best way to determine available energy in a food.
Protein and carbohydrates provide equal amounts of energy in the form of calories, while fats supply 2-1/4 times the calories.
Contrary to the popular myth that excess energy in pet food causes hyperactivity, excess energy is stored as fat, or excreted in the urine.
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