Effects of ascorbyl-2-polyphosphate on adrenocortical activation and fear-related behavior in broiler chickens

The effects of supplemental ascorbyl-2-polyphosphate (APP) on adrenocortical function and underlying fearfulness in broiler chickens were assessed in a number of test situations. Chicks pretreated for a minimum of 24 h with APP (1,000 ppm equivalents of L-ascorbic acid) in their drinking water or with no APP (tap water controls; CON) had blood samples taken immediately following water treatment and again after exposure to a capture and cooping stressor for 10 min. First, although the cooping stressor markedly increased plasma corticosterone concentrations, pretreatment with APP failed to attenuate this adrenocortical response. Second, APP-treated chicks showed less freezing and vocalized sooner in an open field (novel environment) than did controls. They also showed nonsignificant tendencies toward accelerated and enhanced ambulation. Third, supplementation with APP reduced the duration of the birds' tonic immobility fear reactions. Collectively, these behavioral effects are indicative of dampened fear. The apparent reduction of nonspecific, underlying fearfulness by APP treatment may have important implications for poultry welfare and performance.