Abstract. Chitosan adipate was administered orally to broiler chickens to investigate its effect on body weight and protection against Salmonella gallinarum. The study was conducted on 80 six-day-old broiler chickens from the ROSS line that were divided in four groups (20 birds each): I – control; II – infected with S. gallinarum and treated with chitosan adipate; III – infected with S. gallinarum; IV – chitosan adipate treatment only. Chitosan salt was administered as a feed additive in an amount that guaranteed that the chitosan contained in the salts constituted 3% of the chicken diet. (Phenotypic characteristics of Salmonella gallinarum and Salmonella pullorum isolated from layers).

The chickens were infected with a suspension containing 1800x10⁶ bacteria in 2 ml (on the McFarland scale gruppe 3).

The chickens pretreated orally with chitosan were highly resistant to S. gallinarum infection. The clinical symptoms and anatomicopathological changes in chickens infected with bacteria and treated with chitosan (group II) were weak in comparison with chickens infected with S. gallinarum only (group III). Weight gain was significantly higher (by about 12.5%) in the control group than in the chickens infected with S. gallinarum (group III). In the birds that were infected and treated (group II), and in those that were given chitosan (group IV), weight gain was about 2–2.5 % lower in comparison with the control group.