To study the effects of terbutaline (a beta adrenergic agonist) on performance of broiler chickens, 21 d-old male and female Cobb broiler chicks (n=300) were randomly assigned to one of five dietary treatments containing 0 (control), 5, 10, 15 and 20 mg terbutaline per kg diet. The feed conversion ratio (FCR), feed intake and body weight gain were measuered after 3 weeks. At 42-d age, six males and six females were randomly selected from each treatment and their live weight and weights of carcass, breast, breast muscle, drumsticks, drumstick muscle and abdominal fat were determined. Terbutaline didn’t affect daily weight gain, but FCR of male chicks was reduced for 5 and 10 mg/kg terbutaline treatments comapared with the control group (p<0.05). Carcass weight and weight of drumsticks, drumstick muscle, breast, breast muscle and ratio of breast to live weight of female chicks reciving 5 mg/kg terbutaline were higher than for other treatments (p<0.05). In male chicks, the live weight and weight of carcass, ratio of carcass to live weight, drumsticks and drumstick muscle at 5 mg/kg terbutaline treatment were higher than for other treatments (p<0.05). This experiment also showed that the addition of 5 mg terbotaline per kg diet during growing period improved FCR and ratio of carcass to live weight of male chicks, increased the ratio of breast to live weight of female chicks, and increased the carcass weight of male and female Cobb chicks.

Keywords: Beta-adrenergic agonist, Terbutaline, Performance, Broiler chicks.

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