Utilisation of free and protein dietary lysine in chicks estimated with isotopes.
1. Utilisation of supplementary free L-lysine hydrochloride was estimated in growing chicks and compared to that of protein-bound lysine. The technique used is based on the oxidative catabolism of either free (U-14C)-L-lysine or the labelled lysine incorporated into yeast proteins. 2. The animals received a wheat-wheat gluten diet which was L-lysine-supplemented with either unlabelled yeast proteins or a mixture of synthetic amino acids simulating the yeast proteins or L-lysine hydrochloride alone. 3. At 13 and 15 days after hatching, expiry of (14C)--carbon dioxide was followed 8 h after dosing with the appropriate radiolabelled diet. After 4 h, 0.66% of the protein-bound and 5.3 to 5.7% of the free lysine radioactivity appeared as 14C--carbon dioxide. 4. It is concluded that under these conditions lysine from both sources was utilised more efficiently than had been assumed hitherto, protein-bound lysine being slightly better utilised than free lysine.
Otto
M
M
Institute of Animal Physiology, Slovak Academy of Sciences, Ivanka pri Dunaji, Czechoslovakia.
Snejdarkova
M
M
Simon
O
O
D000821:Animal Feed; D000818:Animals; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D004032:Diet; D005260:Female; D005656:Fungal Proteins / Q000008:administration & dosage*; D008239:Lysine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D010084:Oxidation-Reduction; D011897:Random Allocation; D015430:Weight Gain
D005656:Fungal Proteins; D008239:Lysine