Onion leaf and synthetic additives in broiler diet: impact on splenic cytokines, serum immunoglobulins, cecal bacterial population, and muscle antioxidant status

BACKGROUND The disadvantages associated with the use of synthetic additives in animal production could threaten human and animal health, and the safety of animal-derived foods. This study assessed the growth performance, blood chemistry, immune indices, selected caeca bacterial population, muscle antioxidant enzyme activities, and meat quality in broiler chickens fed diet supplemented with antibiotic (70% oxytetracycline +30% neomycin), tert-butylhydroxytoluene or onion leaf powder (OLP). One day old Ross 308 chicks (n = 240) were assigned randomly to either D-1, control diet (CD) without additives; D-2, CD + 0.3 g kg-1 antibiotic +0.15 g kg-1 tert-butylhydroxytoluene; D-3, CD + 2.5 g kg-1 OLP; or D-4, CD + 5 g kg-1 OLP for 42 days. RESULTS The D-2 and D-4 diets improved (P