[Physiological nutrition studies of swine for the evaluation of modified proteins. 3. Relationship between the true and apparent N digestibility and amino acid absorption of the small intestines and the parameters of N metabolism].

Modified proteins were tested in absorption investigations with eight pigs with ileocaecal re-entrant cannulae. The apparent digestibility up to the end of the small intestines showed considerable differences between the feed proteins (77-93%). The same differences could be observed with regard to the apparent absorption of amino acids. Concerning the true N-digestibility resp. the true absorption of the amino acids in the above mentioned section of the intestinal tract there were hardly any differences between the proteins given. The results show that there is a relation between the amount of endogenous N in the chyme at the end of the small intestines and the protein consumed. The amount of endogenous N in the chyme in the small intestines influence N-excretion in urine and thus the intermediary utilisation of feed protein. From the point of view of nutrition physiology it follows that the spun vicia-faba protein/casein (1 : 1) fibres (C) approximate best the value of casein (A). While the treatment of this mixed protein with dyaldehyde starch had a negligible effect on the ascertained parameters only, the treatment of the same protein with aluminium chloride diminished its value more. The isolated vicia-faba (B) was the poorest of the modified proteins tested.