Effects of a beta-adrenergic agonist (clenbuterol) on performance, carcase composition, hepatic microsomal mixed function oxidase and antibody production in female broilers treated with or without corticosterone.

1. Beta-adrenergic agonist (Clenbuterol, 0.33 mg/kg) and corticosterone (10 mg/kg) were incorporated into a diet based on maize and soybean meal. Their effects on performance, carcase composition, hepatic microsomal mixed function oxidase and antibody production were investigated in female broilers. 2. Dietary corticosterone reduced the titre to sheep red blood cells, while it was unchanged by clenbuterol. 3. Clenbuterol exerted a promoting effect on gain-to-food ratio, carcase protein and hepatic microsomal cytochrome P-450 content. 4. Addition of clenbuterol to the corticosterone-containing diet prevented the increase in abdominal fat weight and uric acid excretion induced by corticosterone, but did not affect total fat mass. 5. The results showed that clenbuterol reduced abdominal rather than carcase fat and prevented protein degradation in the body when chicks were treated with corticosterone. Clenbuterol also influenced the content of cytochrome P-450, but not the humoral immunity.