Short chain fatty acids (SCFA), the end products of bacterial fermentation in the large intestine, have many beneficial effects in the gut. The main energy substrates for colonic bacteria are indigestible dietary carbohydrates (dietary fibre, DF), whereas the indigested protein, intestinal secretion and urea serve as the nitrogen sources. Intensity of fermentation and SCFA profile are affected by composition, solubility, degree of lignification and processing of DF but also by the type of dietary protein. The knowledge on the interactive effects of DF and protein may be useful in the nutrition of young pigs. The objective of the study was to estimate the effects of resistant versus highly digestible protein (potato protein, PPC and casein, CAS, respectively) supplemented with DF of high and low fermentabilities (potato fibre, PF and cellulose, CEL, respectively), on the concentration of SCFA in caecum and colon of young pigs. Four groups of six pigs of 15 kg body weight were fed during 21 days on cereal diets containing CAS or PPC and supplemented with PF or CEL.
Total SCFA concentration was not affected by protein source and was significantly greater on PF than on CEL in middle colon. Butyrate concentration tended to be and was greater on PPC than on CAS in caecum (P = 0.07) and proximal colon (P = 0.02) while in the middle colon it was greater only after feeding PPC with PF (P interaction = 0.02). Feeding PPC increased also valerate concentration in caecum and proximal colon while it decreased or tended to decrease acetate in the middle and distal colon. Feeding PF increased acetate in the middle colon, and butyrate in distal colon. It tended also to increase isobutyrate in the middle and distal colon. Feeding PPC to pigs resulted in an increased thickness of mucosa in duodenum and of myenteron in midjejunum as compared with CAS, while the effects of feeding PPC on the morphometry of the colon differed among the segments and depended on the type of fibre: in the proximal and middle colon PPC decreased myenteron width on diets supplemented with PF while in distal colon this effect was opposite.
The results of the study indicate for an interactive effect of fibre and protein on the total SCFA and butyrate concentrations in the colon. Also isobutyrate, acetate and valerate concentrations tended to be modified in a similar way.
M Taciak, B Pastuszewska, A Tusnio and E Swiech, 2010. Livestock Science, 133:138-140.