Effect of clenbuterol on growth, nitrogen and energy balances and endocrine status in food-restricted sheep.

The aim of this study was to examine the effect of the beta2-adrenoceptor clenbuterol on food-restricted sheep. Clenbuterol was administered as a dietary admixture (4 mg/ kg diet) to a group of male Serra da Estrela sheep (n = 6). The animals were housed individually in metabolic cages and fed for 45 days at 65% of estimated requirement for energy maintenance. An untreated group with the same energy intake level was included as a control. Changes in body mass, nitrogen and energy balances and insulin, insulin-like growth factor (IGF-1), and triiodothyronine (T3 ) levels in the experimental animals were monitored. During the 4th week of the trial, clenbuterol-treated sheep showed increased mass gains, greater energy retention and serum IGF-1 levels and decreased T3 serum concentrations. This study showed that clenbuterol may induce a protective effect in sheep subjected to periods of food deprivation, based on the body mass and digestible energy effects manifested by treated animals.