STIMULATION OF THE BRONCHUS-ASSOCIATED LYMPHOID-TISSUE OF GOATS AND ITS EFFECT ON IN-VITRO COLONIZATION BY PASTEURELLA-HAEMOLYTICA

Twenty goats of about 7 months of age were divided into five groups. T he goats in groups 1 and 2 were exposed once, using an intranasal spra y to 2 mi of an inoculum containing 10(6) colony-forming units/ml of l iving or dead Pasteurella haemolytica A2, respectively. The goats in g roups 3 and 4 were similarly exposed twice at a 2-week interval. Group 5 was the untreated control. The number and size of the bronchus-asso ciated lymphoid tissue (BALT) in goats exposed twice to either living or dead organisms were significantly (p<0.05) increased compared with those exposed once and with the unexposed control. In vitro colonizati on by living P. haemolytica A2 onto the lung tissue in which the BALT had been stimulated by two exposures of either living or dead organism s was significantly (p<0.05) reduced. The study indicates that stimula tion of the respiratory mucosal immunity may prevent P. haemolytica A2 infection.