This study characterised the composition of surface and secretion complex carbohydrates in the alimentary
tract of organically and intensively housed chickens. Histochemical labelling was carried out on samples
of oesophagus, glandular stomach and proximal duodenum using (1) alcian blue (AB) at pH 2.5
combined with neuraminidase digestion (Sial) with or without saponification (KOH), (2) AB at pH 1
and 0.5, (3) periodic acid-Schiff (PAS), (4) a 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 visco-elastic 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