The objective was to determine whether recombinant bovine somatotropin (rbST) enhanced live performance,skeletal muscle biological activity, and beta-adrenergic receptor expression of feedlot heifers during the finishing phase. Heifers (n = 16; initial body weight 457 ± 3 kg) were randomly assigned pens (4 pens/treatment; 2 heads/pen) treatment: (1) no rbST (Control); (2) 500 mg/hd sometribove ...