How to Convert Crude Fat Into TDN

Farm animals, just like humans, need a certain amount of calories per day to remain healthy. Total digestible nutrients (TDN) is one way to measure this. The idea is to measure how many calories the animal is taking in, and how many calories are not being used. This is done by taking account of the different parts of the feed, such as ingestible wheat hulls. To calculate crude fat, however, the equation is much more simplified.

Things You'll Need

  • Scale
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Instructions

    • 1

      Measure the weight of the crude fat.

    • 2

      Multiply the weight of the crude fat by 2.25, to account for the higher calorie density of fat, relative to protein and carbohydrates. The average calorie density of protein and carbohydrate is 4 calories per gram, whereas fat contains an average of 9 calories per gram.

    • 3

      Add in other amounts to the formula if you want to add other dietary intake to the crude fat. The complete formula for calculating total digestible nutrients is TDN = digestible crude protein (CP) + (digestible crude fat (EE) x 2.25) + digestible cell wall (NDF) + digestible nonstructural carbohydrate (NSC).