Histochemical characterisation of complex carbohydrates expressed in the alimentary tract of chickens

This study characterised the composition of surface and secretion complex carbohydrates in the alimentary tract of organically and intensively housed chickens. Histochemical labeling was carried out on samples of oesophagus, glandular stomach and proximal duodenum using (1)alcianblue(AB) at pH2.5 combined with neuraminidase digestion(Sial) with or without saponification(KOH), (2)AB atpH1 and 0.5, (3)periodic acid-Schiff(PAS), (4)combined AB–PAS stain, and(5) both low and high iron diamine stains combined with enzymatic treatments specific for glycosaminoglycans. Semi-quantitative scoring of the histochemical staining indicated abundant acidic sulfated glycoconjugates in each alimentary tract region, in addition to the presence of sialoglycoderivatives in the oesophagus. These complex carbohydrate components are likely to have various functions including the provision of a protective viscelastic barrier and a role in the defence against specific pathogens. The findings provide a starting point for a more in-depth study of alimentary tract glycoconjugates in poultry.