Effect of dietary fibre and protein sources on contractility and morphometry of pig colon

The aim of the study was to investigate the effects of feeding two fibre and two protein sources, differing in rate of fermentation and digestion, on motility and morphology of pig colon. Pigs of 15.1 ± 0.9 kg of BW were fed during 21 days with diets containing potato fibre (PF) or cellulose (CEL) in combination with potato protein concentrate (PPC) or casein (CAS). After slaughter, tissue samples of proximal (C25), middle (C50) and distal (C75) part of the colon were taken for analysis of in vitro mechanical activity and of histological parameters. Spontaneous activity, responses to acetylcholine (ACh), electrical field stimulation (EFS), responses to short chain fatty acids (SCFA) and relaxation induced by single administration of isoproterenol were recorded. Crypt depth and myenteron thickness were measured. The amplitude of spontaneous contractions of colon segments was similar in all groups. In neither colon segment, responses to EFS, SCFA and relaxation induced by isoproterenol were not affected by the sources of fibre and protein. Response to ACh was significantly enhanced in C25 in pigs fed CAS as compared with PPC. The effects of type of dietary fibre and dietary protein on colon morphology differed between the segments and parameters under study. The effect of fibre was not found in C50. The effect of fibre type on colon morphology was of greater magnitude than that of protein but in some parameters interactive effects could be traced. The results suggest that effects of type of dietary fibre and protein on colonic morphology depend on the part of the colon. Fibre and protein sources do not affect motility in middle and distal parts of colon, but protein source affects muscular contractions in proximal colon, assayed in vitro.