Effect of Infectious Agents on Chickens Selected for Plasma Corticosterone Response to Social Stress

SOCIAL stress has been found to modify the response of chickens to infectious diseases. Chickens maintained in a more stressful social environment were more susceptible to viral infections and more resistant to bacterial infections than chickens maintained in a less stressful social environment (Gross and Colmano, 1969). High levels of plasma corticosterone were positively correlated with resistance to Escherichia coli infection (Gross and Colmano, 1967). Injection of chickens with corticosterone resulted in increased resistance to E. coli infection (Gross and Colmano, 1970). Chemicals which block the production of corticosterone by the adrenals resulted in increased resistance to viral infections and decreased resistance to E. coli infection (Colmano and Gross, 1971). Brown and Nestor (1970) reported that turkeys could be selected for plasma corticosterone response to cold stress. They found that the major selective modification was on the ability of the adrenals to respond to ACTH. The purpose of these experiments…