The rate of absorption of synthetic lysine and dietary protein in the upper half of the small intestine of pigs.

The aim of the present work was to estimate the rate of lysine absorption in the upper part of the small intestine as related to the absorption of total nitrogen and other amino acids in pigs given feed (barley + sesame meal) supplemented with lysine and fed once or 4 times daily. The experiments were carried out on 6 pigs fitted with reentrant cannulas sited in 3 of them about 4 m and in an other 3 about 9 m distal to the pylorus (mean intestine length was about 18 m). The frequency of feeding influenced the rate of flow of total nitrogen and lysine through the intestine. The content of lysine in the digesta (g/16 g N) during the first 5 hours after morning feeding, and particularly between 8.00-10.00 h, was much higher with once daily than with four times daily feeding while during the subsequent 15 hours the reverse was true. The absorption of lysine occurred at a faster rate than that of the other amino acids and was closest to that of arginine and methionine. On the whole, the net absorption rate of essential amino acids in the upper part of the intestine of pigs was as follows: Lys, Met greater than His, Phe, Leu greater than Trp, Ile, Val greater than Thr (Cys). It seems that the more uniform passage through and absorption from the alimentary tract of synethetic lysine and dietary protein, observed at frequent feeding could contribute to their better utilization for protein synthesis in the organism.