[Dependence of metabolic fecal amino acids on the amino acid content of the feed. 1. Metabolic fecal amino acids of rats fed with maize].
The amount of metabolic fecal amino acids (MFAA) in dependence on the amino acid intake was determined for graded maize rations with 15N-labelled rats and the quota of labelled endogenous amino acids in faeces was calculated according to the isotope dilution method. The excretion of amino acids and MFAA in faeces are described as functions of the amino acid intake for 17 amino acids and regressively calculated. For all 17 amino acids investigated, there was a more or less steep increase of MFAA according to an increasing amino acid intake. In contrast to MFAA in N-free feeding, MFAA in feeding with pure maize (16.5% crude protein) increase to the 2- to 4.5-fold value. The thesis of the constancy of the excretion of MFAA can consequently be no longer maintained. The true digestibility according to the conventional method is, on an average of all amino acids, 7.3 units below the one ascertained according to the 15N-isotope method. For the limiting amino acids lysine and threonine the difference is biggest (23 resp. 17 units). Tryptophane as first limiting amino acid could not be determined. The true digestibility of nearly all amino acids ascertained for maize according to the isotope method is above 90%. For the limiting amino acids the expenditure resp. the loss of endogenous amino acids is biggest.
D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D005243:Feces / Q000032:analysis*; D009587:Nitrogen Isotopes; D051381:Rats / Q000378:metabolism*; D003313:Zea mays
D000596:Amino Acids; D009587:Nitrogen Isotopes
Abhängigkeit der Darmverlustaminosäuren vom Aminosäurengehalt des Futters. 1. Mitteilung. Die Darmverlustaminosäuren bei Maisfütterung von Ratten.