Abstract
Performance of chickens is negatively impacted by stressors such as heat stress, infection with Campylobacter jejuni, the mycotoxins –aflatoxin B1 and deoxynivalenol, the glucocorticoid dexethasone, insecticides and Eimeria tenella. Effects of stressors include reduced gastrointestinal function and induction of inflammation. Stressors influence the following molecular and cellular structures and functions: gastrointestinal integrity, villus height, crypt depth, mast cell number, expression of pro-inflammatory cytokines, concentrations of leukocytes, and antioxidant status. In multiple studies, adverse effects of multiple stressors were overcome partly by supplementation. The utility of these parameters is discussed and recommendations/guidelines for future research made.