The Influence of Zinc Bacitracin on the Colonization of Salmonella infantis in the Intestine of Broiler Chickens

Summary The effect of zinc bacitracin on the growth of Salmonella infantis in the intestine of experimental orally infected 2-day-old broiler chicks was studied. At the age of 5 weeks the chicks which had received zinc bacitracin showed a lower incidence of salmonellae than those in the control group. Chicks pretreated with the intestinal flora of adult fowls (Callus domcsticus), whether receiving zinc bacitracin in the feed or not, were equally resistant against the colonization of S. infantis as compared with chicks which had no such pretreatment. The intestinal flora of adult fowls cultured in vitro, with or without zinc bacitracin, prevented the colonization of S. infantis, while flora from the same source cultured with tetracycline hydrochloride lacked this effect.