Resumen

ECHEVERRI ZULUAGA, José Julián; GOMEZ ZAPATA, Andrés  y  PARRA SUESCUN, Jaime Eduardo. Methodologies used for the measurement of endogenous intestinal nitrogen losses in growing pigs. Rev. Lasallista Investig. [online]. 2009, vol.6, n.1, pp.75-82. ISSN 1794-4449.

Amino acid ileum digestibility is one of the most important factors to determine the nutritional value of foods. However, the values obtained in ileum digestibility tests can vary according to the endogenous nitrogen losses in the animal. Thus, ileum digestibility values can be classified as apparent or true. When determining the apparent value, endogenous nitrogen losses are not taken into account and the amounts of absorbed amino acid during digestion are then underestimated. When the endogenous component is taken into account, digestibility data become true, being the best parameter to represent absorbed amino acid in the digestive tract. Endogenous nitrogen losses are classically defined as the nitrogen found in the digesta or in the feces of animals fed with nitrogen-free diets. Traditionally, endogenous nitrogen losses in pigs have been determined by feeding nitrogen-free diets or by the lineal regression method. More recently, several alternative techniques have been developed to evaluate endogenous nitrogen losses in pigs that are fed with diets that contain variable protein levels. Each of these techniques has some limitations and all require different assumptions. Based on the increasing number of results recently obtained with different techniques, endogenous nitrogen losses seem to be highly affected by the used method and by factors as weight, dry matter consumption, and diet components (anti nutritional factors, fiber and protein).

Palabras clave : Endogenous nitrogen flow; growing pigs; quantification techniques.

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