Influence of Dietary Supplementation of Guava Leaf, Oxytetracycline, and Tert‐Butylhydroxytoluene on Growth Performance, Gut Microbial Population, Immune Status, Carcass, and Meat Quality in Broiler Chickens

This study investigated the effects of dietary supplementation of guava leaf (GL), oxytetracycline, and tert-butylhydroxytoluene on growth, immune status, gut microbial population, and meat quality of broiler chickens. A total of 280 Ross 308 one-day-old chicks w ere randomly allotted to either G-0; basal diet (BD) without additive; G-1; BD + 0.5 g/kg oxytetracycline + 0.15 g/kg tert-butylhydroxytoluene; G-2; BD + 2.5 g/kg GL; or G-3; BD + 5 g/kg GL for six weeks. At 1-21 d, G-1 and G-2 birds had higher (P<0.05) body weight gain (BWG) and feed efficiency compared with G-0 and G-3 birds. At 22-42 d, the supplemented birds consumed more feed than the G-0 birds. At 1-42 d, BWG and feed intake were higher (P<0.05) in the supplemented birds compared with the G-0 birds. Hematological indices were not affected by the diets. GL-supplemented birds had lower (P<0.05) serum and meat cholesterol than the G-0 and G-1 birds. The G-0 birds had higher tumor necrosis factor-α (83.69 pg/mL) and lower interleukin-10 (5.84 pg/mL) than birds fed other diets. The G-3 birds had lower (P<0.05) interleukin-1β and immunoglobulin M than other birds. Dietary supplements lowered (P<0.05) clostridium, coliforms, and salmonella counts in caecum and ileum. GL-supplemented birds had a higher ileal Lactobacillus count than G-0 and G-1 birds. Carbonyl and malondialdehyde contents were lower (P<0.05) in the supplemented meat on day 4 postmortem. Antioxi-dant enzymes and total antioxidant capacity were higher in the G-3 meat compared with other meats. Breast meat quality was not affected by diet. GL could be a potent antioxidant and antimicrobial in broiler diets.