Determination of endogenous nitrogen

The magnitude of the endogenous nitrogen component may be estimated by one of the following procedures  

Adapted from Sauer W C and de Lange K 1992 Novel methods for determining protein and amino acid digestibility values in feedstuffs. In Nissen S (ed.) Modern Methods in Protein Nutrition and Metaboiism, London, Academic Press. 

Most of the figures in current use are apparent values, but in feeding systems in which metabolic nitrogen loss is treated as part of the maintenance nitrogen demand, true rather than apparent coefficients have to be used. 

There is evidence that figures for the apparent ileal digestibility of lysine, and some other amino acids, overestimate availability to the animal, which reinforces the view that it is dangerous to equate digestibility with availability. 

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