[Nutritional and physiological studies of swine for the evaluation of modified proteins. 2. Determination of endogenous N in the contents of the small intestines using the 15N-tracer method].

The endogenous N-quota in the chyme of the small intestines after providing modified proteins was determined with re-entrant cannulae at the end of the ileum in investigations with pigs (35 to 50 kg live weight) with the isotope dilution method. The N-pool of the test animals was labelled with 15N-glycine and 15N-leucine. The TCA-soluble fraction of the blood plasma served as criterion for the labelling level of the N-pool. The results showed a direct connection between N-intake and endogenous N in the chyme of the small intestines. With regard to N-intake, the dependence of endogenous N in the chyme of the small intestines on feed protein could be observed.