Effects of dietary corticosterone on peripheral blood lymphocyte and granulocyte populations in immature domestic fowl.

Four-week-old chickens were fed on diets containing 0, 5, 10, 20 and 40 mg corticosterone per kg for eight days. Packed cell volume (PCV), the numbers of granulocytes (G) and lymphocytes (L), the G:L ratio and plasma corticosterone concentration were measured. Plasma corticosterone concentration was increased by dietary corticosterone from day 2 onwards. The number of lymphocytes was increased by serial bleeding but dietary corticosterone depressed the response and caused a dose-related lymphocytopenia from day 1. There was a dose related increase in granulocytes from day 4 and a dose-related increase in G:L ratio from day 1. A dose-related increase in PCV was evident only on days 2 and 4. Correlation coefficients showed little evidence of relationships between plasma corticosterone concentrations and the recorded blood variables.