Effect of viscosity on digestion of nutrients in conventional and germ-free chicks

Abstract

A study was conducted with conventional and germ-free broiler chicks to obtain more information on the role of the intestinal microflora in the anti-nutritive effects of NSP in broiler chicks. As the NSP source, highly methylated citrus pectin (HMC) was used at a dose level of 30 g/kg in a maize-based diet. The diets fed to the germ-free chicks were γ-irradiated, whereas those fed to the conventional chicks were not. Feeding the HMC diet to conventional birds depressed weight gain and food utilization (P < 0·05), whereas in germ-free birds only weight gain was reduced (P < 0·05). Feeding the HMC diet to conventional birds reduced digestibilities of energy and starch at the end of the jejunum. Ileal digestibilities of starch and energy were not strongly affected when birds were fed on the HMC-containing diet. Faecal digestibilities of organic matter, crude fat, starch and amino acids, N retention and metabolizable energy were reduced when conventional chicks were fed on the HMC diet. Feeding the HMC diet to germ-free birds hardly affected faecal digestibility of nutrients and N retention, whereas metabolizable energy was increased. Feeding the HMC diet to conventional or germ-free birds increased the viscosity of the digesta in the small intestine. This increase in digesta viscosity was more pronounced in conventional than in germ-free birds. The pH of ileal digesta was reduced when HMC was added to the diet of conventional chicks, but not in germ-free chicks. Feeding the HMC diet to conventional birds markedly affected morphology of the gut wall, whereas in germ-free chicks very little effect was found on gut morphology. Based on the results of the present study, it is concluded that the gastrointestinal microflora mediates the magnitude of the anti-nutritive effects of HMC in broiler chicks. However, the exact role of the microflora in chicks in the magnitude of the anti-nutritional effects of HMC could not be derived from the present study, since the results might have been influenced by γ-irradiation of the diets fed to the germ-free chicks.

Effects of dietary essential oil components on growth performance, digestive enzymes and lipid metabolism in female broiler chickens

“…Under the conditions of this experiment, including the composition of the diet, the basal activities of digestive enzymes did not appear to limit macronutrient digestibility. In any event, the observed digestibilities of starch, protein and fat were rather high when compared with previous work (Smits et al, 1998;Langhout et al, 2000); under such circumstances any improvements in digestibilities would have been impossible, or would have been difficult to detect.…”

High-viscosity carboxymethylcellulose reduces carbachol-stimulated intestinal chloride secretion in weaned piglets fed a diet based on skimmed milk powder and maltodextrin

“…This would be consistent with the lack of marked alterations in intestinal architecture and enzyme activities, the lack of increased chloride secretory capacity, and the unaltered growth and ileal digestibility of nutrients in our CMC pigs (present results; Piel et al 2005). Langhout et al (2000), using germ-free chicks, demonstrated that the intestinal microflora contributes to increased digesta viscosity and small-intestinal alterations, and to reduced nutrient digestibility in the small intestine and faeces of birds. Whether bacterial adhesion of pathogenic E. coli to intestinal epithelial cells is influenced by NSP is not known.…”

“…Faeces inconsistency might have reflected the water-holding and gelling capacities of CMC, which were maintained in the faeces since CMC is not fermented (Wyatt et al 1988;McDonald et al 2001). Increased water consumption often seen with CMC supplementation (Smits et al 1997;Langhout et al 1999Langhout et al , 2000 might have also contributed to the water retained by CMC in the digesta and to the increased faecal water losses. Improved Na-dependent glucose absorption in the present study is in agreement with the observation that medium-viscosity CMC increased absorption of Na and water in the perfused jejunum of both control rats and those with induced osmotic diarrhoea (Go et al 1994).…”

“…Soluble non-digestible NSP including guar gum, high-methylated citrus pectin and carboxymethylcellulose (CMC) have been used as model compounds to increase viscosity and to explore its influence on gastrointestinal function in rats (Blackburn & Johnson, 1981), chickens (van der Klis et al 1993a,b;Smits et al 1997Smits et al , 1998Langhout et al 1999Langhout et al , 2000 and pigs (McDonald et al 1999(McDonald et al , 2001Montagne et al 2004). The bulk of digesta was usually increased along the gut while digestion and nutrient absorption were reduced.…”

“…Alterations in small-intestinal architecture were also noted. In birds, it was clearly demonstrated that the intestinal microflora mediated the magnitude of disorders, since germ-free chicks displayed neither reduced digestibility nor intestinal tissue alterations (Langhout et al 2000). From these data it is usually considered that NSP reduce the absorption of glucose and water from the small intestine, favouring diarrhoea.…”