Evaluating Alternatives to Zinc-Bacitracin Antibiotic Growth Promoter in Broilers: Physiological and Meat Quality Responses

Abstract

This study evaluated different combinations of a probiotic (Bacillus licheniformis), an organic acid mixture (benzoic and fumaric acids), a protease enzyme, and chelated minerals (Cu, Zn, and Mn) as alternatives to zinc-bacitracin antibiotic. Eight hundred Cobb 500 chicks (42.02 ± 2.207 g liveweight) were distributed into 40 pens to which five diets: 1. Commercial broiler diet with no antibiotics (CON); 2. CON + zinc-bacitracin antibiotic (ZnB); 3. CON + chelated minerals + protease enzyme (MinEnz); 4. CON + chelated minerals + protease + organic acids (MinEnzOrg); and 5. CON + chelated minerals + protease + probiotic (MinEnzPro) were allocated. Probiotic, minerals, protease enzyme, and organic acids were included in diets at 0.2 g/kg, 0.3 g/kg, 0.5 g/kg, and 5 g/kg, respectively. Diets promoted a similar feed intake, weight gain, and feed conversion ratio. Birds on MinEnz had the highest basophil content (2.04 × 109/L), while those on ZnB had the highest alanine aminotransferase (8.50 IU/L). Chickens on MinEnz had the heaviest spleens and the largest proventriculi. Meat from CON birds had the highest water holding capacity (22.32%) and cooking losses (27.15%). We concluded that the investigated combinations of feed additives could replace ZnB in broiler diets as they promoted similar growth performance and carcass characteristics.