Effect of non-starch polysaccharides on production and absorption of indolic compounds in entire male pigs

Abstract

AbstractIn order to study the effect of feeding non-starch polysaccharides (NSP) on the production and absorption of the malodorous compounds skatole and indole, eighteen male pigs, representing nine littermate groups, were used. One pig from each litter was assigned to either a low-NSP diet (87 g/kg of NSP) or a high-NSP diet (160 g/kg of NSP). Faecal samples and blood samples from vena jugularis were collected during a three-day period. The production of indolic compounds in different sections of the gastro-intestinal tract of six littermate groups was measured at slaughter (after 1 month on the diets). To investigate the absorption of indole and skatole, three catheterized pigs, acting as their own control (2 weeks on each diet) were used. Parallel determinations in portal blood, peripheral blood and in faeces of skatole and indole were conducted. Faecal, intestinal and blood samples were analysed for indolic compounds by high-performance liquid chromatography (HPLC). The production of indole and skatole in the proximal and distal part of the hind gut, respectively, was significantly reduced in pigs given the high-NSP diet. Similarly, both blood and faecal samples revealed that dietary NSP-inclusion reduced skatole concentration, whereas a dietary effect of NSP on the indole concentration was reflected in blood samples only. The absorption of skatole and indole was significantly lower in pigs given the high-NSP diet compared with those offered the low-NSP diet. The skatole concentrations in blood and faeces were highly correlated when measured within the individual animal, suggesting that a proportional amount of the skatole produced was absorbed. In contrast, only weak correlations were demonstrated when determined between animals. This emphasizes the great impact that individual hepatic clearance rate would have on the level of skatole in backfat, and consequently the importance of applying cross-over designs, when studying the absorption of indolic compounds.