Inge Helmer Knap

The digestibility of carbohydrates, protein and fat in the small and large intestine of piglets fed non-supplemented and enzyme supplemented diets

The digestibility of carbohydrates, protein and fat was studied in 8- to 12-week-old piglets fitted with a T-shaped cannula at the terminal ileum and fed two diets based on barley and wheat as the cereal source and with protein from soybean meal (diet CS) or pea, soybean meal and rapeseed cake (diet CPSR). The diets were fed either alone or supplemented with single enzymes (α-galactosidase, xylanase, β-glucanase, α-amylase, protease) or with a mixture of enzymes (α-galactosidase, xylanase and protease). After completing the digestibility trials, four piglets on each of the two basal diets were slaughtered and samples of digesta were taken along the gastrointestinal (GI) tract for additional measurements of carbohydrates and organic acids. Three hours after the meal the disappearance of raffinose oligosaccharides (raffinose, stachyose and verbascose) was about 39% as measured in the pooled digesta from the stomach and the small intestine. Digestibility of raffinose oligosaccharides at the terminal ileum was 86–90%. The relatively high digestibility in the upper intestine is most likely caused by endogenous plant and microbial α-galactosidases. The digestibility of starch at all sampling points along the GI tract was significantly higher with diet CS than with diet CPSR, while the digestibility of protein, fat and non-starch polysaccharides was similar for the two diets. In the large intestine, pectin was more rapidly and extensively digested than cellulose, arabinoxylans and xylan polysaccharides but the fermentation yielded similar proportions of acetate, propionate and butyrate. The supplementation of diet CS with xylanase or diet CPSR with the enzyme mixture, increased the digestibility of xylose of diet CS and xylose, arabinose and mannose and DM of diet CPSR. None of the other enzymes, however, improved the digestibility of nutrients.