Effects of handling on plasma corticosterone concentrations in the immature domestic fowl

Abstract

1. 1. Chicks from five strains, aged 1 or 21 days were tested in the morning and afternoon. 2. 2. Two responses were found in the neonate: in the immature, the corticosterone concentration declined; in the mature, there was an initial increase then a decrease. The timing of maturation varied between strains. 3. 3. In the older chicks the initial increases were similar irrespective of the time of day: thereafter in three strains the concentrations were greater in the morning, but in two the reverse occurred. 4. 4. The percentage increase in corticosterone concentration was negatively correlated with the initial concentration.