EFFICACY OF PROCAINE PENICILLIN AS A GROWTH PROMOTER IN BROILER CHICKS FED LOW AND HIGH FIBRE DIETS IN THE TROPICS

The growth promoting efficacy of procaine penicillin when supplemented at the rate of 100 mg kg-1 into 50 g kg-1 and 250 g kg-1 brewers dried grains (BDG) based diets were compared with a control diet without a fibrous ingredient. Growth performance, nutrient intakes and retention, and haematological indices of the broiler chicks were determined during the 35-day study. The aim of the study was to investigate antibiotic supplemen-tation as a nutritional strategy to expand the utili-zation of cheap fibrous feedstuff in broiler diets. The results showed that procaine penicillin stimulated higher (p<0.05) feed intakes, heavier body weights and daily gains in both 50 g kg-1 and 250 g kg-1, and resulted into a better (p<0.05) feed conversion only on 50 g kg-1 BDG. The calorie intakes by the birds were similar, but protein and dietary crude fibre intakes of broilers fed 250 g kg-1 BDG was higher (p<0.05) than others. However, the apparent retention of dry matter, crude protein, and ether extract were similar on the treatments though the values appeared to decrease with inclusion of BDG. All the hematological and erythrocytic indices, serum proteins and urea concentration were unaffected except cholesterol concentration that was signifi-cantly (p<0.05) reduced in broilers fed 250 g kg-1 BDG. It was concluded that penicillin supplementa-tion effectively promoted broilers weight gain and feed conversion, and it appears a feasble strategy to achieve high inclusion rates of low-cost fibrous ingredients such as brewers dried grains in broiler diets. RESUMEN Se comparó la eficacia promotora del creci-miento de la penicilina procaína a tasas de 100 m