1. Digesta were collected from twenty-three pigs, initially of 30 kg live weight, and fitted with single Ash re-entrant cannulas in either the duodenum, jejunum or ileum. A further twenty-four pigs were used in a conventional digestibility trial.
2. Three approximately isonitrogenous diets were used; they contained: barley, fine wheat offal, white fish meal, minerals and vitamins (diet BWF), starch, sucrose, maize oil, cellulose, minerals, vitamins and either groundnut (diet SSG) or casein (diet SSC).
3. The flow-rates of nitrogen (N), liquid-fraction N (LN) and non-protein liquid-fraction N (NPLN) were measured hourly in the duodenum and jejunum and every 6 h in the ileum during 24 h collection periods. Faeces were collected during 5 d periods.
4. Marked increases in flow of N, LN and NPLN were seen in the duodenum and jejunum after feeding each diet, but not in the ileum.
5. Values for, N output: intake from the duodenal, jejunal or ideal cannulas and in faeces in 24 h periods were respectively: 0.98, 0.88, 0.25 and 0.21 for diet BWF; 1.00, 0.97, 0.22 and 0.24 for diet SSG; 0.98, 0.73, 0.09 and 0.03 for diet SSC. The corresponding values for LN in the duodenum, jejunum and ileum respectively were: 0.53, 0.53 and 0.12 for diet BWF; 0.46, 0.60 and 0.13 for diet SSG; 0.57, 0.50 and 0.06 for diet SSC. The corresponding values for NPLN in the duodenum, jejunum and ileum respectively were: 0.41, 0.38 and 0.09 for diet BWF; 0.35, 0.36 and 0.08 for diet SSG; 0.46, 0.38 and 0.04 for diet SSC.
6. The results are discussed in relation to similar studies, particularly in pigs with duodenal cannulas, in which widely different observations were made.