The effect of stress conditions on exocrine pancreatic secretion in growing pigs

Introduction Competition and aggression in pigs is known to reduce daily weight gain (DWG) (R und GREN and L& ouml ; fqvist 1989; H yun et al. 1998; L und et al. 1998), and to impair feed conversion ratio (W alker 1991; L und et al. 1998). The exact biological mechanisms behind these effects are not fully understood. Aggression and competition activate a cascade of reactions of biological relevance, such as inhibition of the parasympathetic nervous system, stimulation of the sympathetic nervous system, including the adrenal medulla (A xelrod et al. 1970; D alin et al. 1993a, 1993b), and activation of the hypothalamo‐hypophyseal‐adrenal (HHA) axis resulting in higher adrenocorticotropic hormone (ACTH) and higher cortisol concentrations in the plasma (D alin et al. 1993b; O lsson and S vendsen 1997). These responses as well as muscular activity increase metabolic losses (S chrama et al. 1993). Hyper‐physiological treatment with glucocorticoids stimulates pancreatic amylase activities in piglets (B aintner and N emeth 1982; C happle et al. 1989a, 1989b, 1989c), but no observations in growing pigs have been published. Inhibition of the parasympathetic nervous system (C hey et al. 1979) and stimulation of the sympathetic nervous system (C hey 1991) reduce exocrine pancreatic secretion. So, there might be some conflicting physiological responses of the exocrine pancreas to stress conditions. In order to increase our understanding of the animal’s physiological responses to conditions of stress, we tested the hypothesis that conditions associated with stress (mixing with unfamiliar pigs, frustration and ACTH treatment) reduce exocrine pancreatic secretion. In addition, we tested the effect of treatment with Amperozide (a neurolepticum which reduces aggression and the effects of stress in pigs) on exocrine pancreatic secretion.