Effects of ammonia exposure on growth performance and cytokines in the serum, trachea, and ileum of broilers

This study investigated the effects of ammonia (NH₃) exposure (0, 15, 25, and 35 ppm) on growth performance and cytokines in the serum, trachea, and ileum of broilers. A total of 288 22-day-old male broiler chickens were assigned to 4 treatment groups with 6 replicates of 12 chickens for a 21-D trial period. Growth performance and cytokines (IL-1β, IL-6, and IL-10) concentrations in the serum, trachea, and ileum were measured in response to 3, 7, 14, or 21 D of exposure to NH₃. Correlations between cytokines in the serum, trachea, and ileum and growth performance, and between tracheal and ileal cytokines, were also analyzed. Results showed that exposure to 15 ppm NH₃ did not influence the growth performance, but exposure to both 25 ppm and 35 ppm NH₃ decreased the growth performance compared to that of the control group. Exposure to 15 ppm NH₃ for 3 D increased IL-6 concentrations and induced an inflammatory response in the trachea and ileum, whereas exposure to 15 ppm NH₃ for 7 D increased IL-10 concentrations and induced an anti-inflammatory response in the ileum. Exposure to 25 ppm NH₃ induced an inflammatory response in the serum, trachea, and ileum after 3 D and induced an anti-inflammatory response in the ileum after 7 D. Exposure to 35 ppm NH₃ for 3 D induced both inflammatory and anti-inflammatory responses in the trachea and ileum. Furthermore, increases in cytokines in the serum, trachea, or ileum were accompanied by a decrease in BW, ADFI, ADG, and an increase of feed/gain (F/G) from 7 D to 21 D. In addition, tracheal cytokine, especially IL-1β, was positively correlated with ileal cytokine IL-1β. These results indicated that the low growth performance associated with NH₃ exposure may be due in part to an increase in cytokines, and the inflammatory response in the trachea and ileum may be related to cross-talk by cytokines such as IL-6, IL-10, and, in particular, IL-1β.