ABSTRACT
This chapter addresses the biology of the responses of livestock and poultry to stress. The major adrenal glucocorticoid in livestock is cortisol (F). The most frequently used method to determine circulating concentrations of F in livestock is radioimmunoassay (RIA). Corticosteroid binding globulin (CBG or transcortin) binds both corticosterone (CORT) and F in respectively poultry and livestock blood. In livestock, circulating concentrations of CBG are influenced by physiological state, for instance, being decreased with heat stress in pigs and increased in late fetal development. The effects of glucocorticoids on growth and metabolism have been extensively investigated in poultry and livestock. There are other immunosuppressive effects of glucocorticoids in livestock and poultry. There are effects of stressors on other hormones in livestock and poultry. Stress is associated with increases in the circulating concentrations of growth hormone (GH) in pigs but suppressed circulating concentrations of GH in poultry.
