Changes in the mucopolysaccharide composition of mucus in ileal mucosal goblet cells from cattle infected with Mycobacterium avium subspecies paratuberculosis

Samples of ileum from 34 Holstein and Jersey cows from 5 herds naturally in fected with paratuberculosis were examined using bacterial cultures and his tochemical methods. The mucopolysaccharide composition of mucus formed in g oblet cells of ileal mucosa was determined by staining samples of the mucos a with alcian blue at pH 2.5 and PAS reaction. This staining allowed us to distinguish neutral mucins and glycoproteins from sialomucins and mixed muc ins. In the ileal goblet cells from 13 cows in which no Mycobacterium avium subspecies paratuberculosis was detected by culture and histological metho ds, neutral mucins and glycoproteins formed the major component of mucus. M ixed mucins were present less frequently and sialomucins least frequently. In 13 cows with subclinical paratuberculosis the number of goblet cells wit h neutral mucins and glycoproteins increased and the number of goblet cells with sialomucins and mixed mucins decreased. In 8 cows with clinical parat uberculosis sialomucins were never present, the level of mixed mucins decre ased and neutral mucins and glycoproteins prevailed. Flattening and diminut ion of the goblet cells of ileal mucosa were observed in cows with clinical paratuberculosis.