Effect of varying levels of benzoic acid on growth performance, haemato-biochemical indices, carcass traits, gut morphology and intestinal microbiota of broiler chickens

This study evaluated the effects of varying dietary levels of benzoic acid on the growth performance, haemato-biochemical indices, carcass traits, gut morphology, and intestinal microbiota of broiler chickens. A total of 300 day-old male Arbor acre broiler chicks were assigned to five dietary treatments supplemented with 0, 2.5, 5.0. 7.5, and 10.0 g/kg benzoic acid in a completely randomized design for 42 days. Results indicated that dietary inclusion of benzoic acid significantly influenced the growth performance, with the highest body weight gain (BWG) and improved feed conversion ratio (FCR) observed at 5.0 g/kg inclusion level (P < 0.001). Haemtao-biochemical indices showed that total protein and globulin levels were significantly higher (P < 0.05) at 7.5 and 10.0g/kg, whereas cholesterol, glucose, and uric acid levels decreased with increasing benzoic acid inclusion (P < 0.05). Carcass traits significantly improved at 5.0 g/kg, with higher breast and thigh muscle yields (P < 0.05). Gut morphology was significantly enhanced, with increased villus length, crypt depth, and epithelium thickness at 5.0 and 7.5 g/kg (P < 0.05). The intestinal microbial analysis revealed a dose-dependent effect, Lactobacillus and Bifidobacteria peaked at 7.5 g/kg, while Salmonella decreased progressively with increasing benzoic acid levels (P < 0.001). In conclusion, benzoic acid supplementation at 5.0 g/kg optimally enhances broiler performance, gut health, and microbial balance, whereas higher inclusion levels may induce metabolic adaptations or stress responses.