[Metabolism-oriented lysine requirement of mature rats based on the catabolism rate for 14C- and 15N-labelled lysine].
Mature male albino rats (ca. 300 g body mass) received 10 diets with a varying lysine content (1.6 to 8.4 g/16 g N). In one partial test the animals were fed ad libitum and in another partial test they were kept in the state of maintenance by limiting the amount of the diet. After 7 feeding days the catabolisation of 14C-lysine into 14CO2 was measured and after 8 feeding days the 15N-excretion in urine after 15N-lysine doses was ascertained. Based on these characteristics typical of metabolism, which show increased catabolisation of the amino acid after the lysine requirement was met, the lysine requirement of a mature rat was determined as 3.5 to 4.0 g/16 g N in the diet. In conclusion, this shows that the lysine requirement in the state of maintenenace and of mature animals is considerably lower than during the period of growth.
D000818:Animals; D002250:Carbon Radioisotopes; D008239:Lysine / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D009587:Nitrogen Isotopes; D009751:Nutritional Requirements; D051381:Rats
D002250:Carbon Radioisotopes; D009587:Nitrogen Isotopes; D008239:Lysine
Stoffwechselorientierte Lysinbedarfsbestimmung bei ausgewachsenen Ratten anhand der Katabolisierungsrate von 14C- und 15N-markiertem Lysin.