A completely randomized design with five replicates and 150 chicks per experimental unity were used to evaluate the effect of growth promoters on feed intake, weight gain and feed:weight gain ratio of broilers. The experimental diets were: 1- initial diet (20.2% of crude protein and 2931kcal of metabolizable energy) from 1 to 20 days of age (ID) and final diet (18.5% of crude protein and 2993kcal of metabolizable energy) from 21 to 40 days of age (FD); 2- ID plus 0.02% of Calsporin10 probiotic and FD plus 0.02% of Calsporin10 probiotic; 3- ID plus 2.0% of probiotic Estibion and FD plus 0.63% of probiotic Estibion; 4- ID plus 0.013% of Zinc bacitracin and FD plus 0.013% of Zinc bacitracin. During the initial period broilers fed on probiotic diets showed lower feed intake and better feed:weight gain ratio. However growth promoters have no effect on the studied traits in the final and total periods. Higher thigh yields were observed for male fed on poliprobiotic diets.
broiler; antibiotic; performance; probiotic; carcass; yield