We examined the effects of thiamine-hydrochloride (10 mg/kg body weight) and a beta-agonist, clenbuterol (50 microg/kg body weight), on plasma metabolites and hepatic oxygen consumption in female broiler chicks. 2. Clenbuterol, thiamine or both, dissolved in saline, were injected into thigh muscle on 2, 4 and 6 d of age. At 7 d of age blood samples in each treatment group were obtained and breast muscle and liver were weighed; liver slices were used for measurement of oxygen consumption. 3. Body weight gain was reduced by clenbuterol. Thiamine increased breast muscle weight as a proportion of body weight regardless of clenbuterol dose. Clenbuterol increased relative liver weight markedly, especially when chicks received thiamine also. 4. Clenbuterol increased plasma free fatty acid concentration in chicks treated with thiamine. Thiamine decreased plasma triglyceride regardless of clenbuterol dose. Plasma glucose concentration was decreased by both thiamine and clenbuterol. 5. The absolute rate of oxygen consumption in liver slices was greater in the thiamine-treated chicks; clenbuterol did not affect hepatic oxygen consumption. 6. These findings suggest that thiamine-induced energy expenditure results not only from thermogenesis in the liver, but also from increasing energy utilisation for muscle hypertrophy and this vitamin supplementation facilitates the lipolytic effects of the beta-agonist.
