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

SIMPLE SUMMARY: In the Global South, the indiscriminate use of antibiotic growth promoters (AGP) in chicken diets continues to pose a threat to human health. However, since infectious disease burden in these regions is high, withdrawing the use of AGP without alternatives would result in proliferation of infections with serious consequences for food and nutrition security and human health. The effectiveness of different combinations of alternative feed additives (a probiotic, live Bacillus subtilis), an organic acid mixture (benzoic and fumaric acids), a protease enzyme, and chelated minerals (Cu, Zn and Mn) was assessed in broiler chickens. When fed on diets containing these alternative feed additives, broilers had similar feed utilization efficiency and growth performance as those fed on an AGP. These findings show that there is potential to replace zinc-bacitracin AGP in broiler diets with feed additives that do not promote antimicrobial resistance and thus deliver safe poultry products. 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 × 10(9)/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.