Abstract
This experiment was conducted to investigate the effects of dietary supplementation with Bacillus amyloliquefaciens CECT 5940 (BA-5940) on growth performance, antioxidant capacity, immunity, and digestive enzyme activity of broiler chickens. A total of 720 one-day-old Arbor Acres male broiler chicks (average body weight, 45.87 ± 0.86 g) were randomly allocated to 5 treatments of 8 replicates with 18 chicks in each replicate. Broilers in the control group were fed a corn-wheat-soybean basal diet, the other 4 groups were fed the same basal diet supplemented with 500, 1,000, 1,500, or 2,000 mg/kg Ecobiol (1.27 × 10(9) CFU/g BA-5940) for 42 d, respectively. Broilers fed diets supplemented with BA-5940 showed a quadratic response (P < 0.05) of average daily gain (ADG) and feed to gain ratio (F:G) during d 22 to 42 and d 0 to 42. The glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities in serum and liver, and total antioxidant capacity (T-AOC) in liver of broilers on d 42 increased linearly (P < 0.05) with increasing levels of BA-5940, while malondialdehyde (MDA) level in serum decreased linearly (P < 0.05). Concentrations of serum immunoglobulin (Ig) A and IgM on d 21, and IgM on d 42 increased linearly (P < 0.05) as BA-5940 levels increased. Supplementation with increasing levels of BA-5940 linearly decreased serum tumor necrosis factor-α (TNF-α) levels on d 21 and 42, while increased interleukin (IL)-10 concentration (linear, P < 0.05) on d 21. Meanwhile, the levels of IL-1β, IL-6, and TNF-α in the mucosa of jejunum and ileum were decreased (linear, P < 0.05) on d 42 as dietary supplementation of BA-5940 increased. Additionally, supplementation with BA-5940 also increased the activities of amylase (linear, P < 0.01), lipase (linear, P < 0.05) and chymotrypsin (linear, P < 0.01) in jejunal digesta, and lipase (linear, P < 0.05) in ileal digesta of broilers on d 42. To summarize, inclusion of BA-5940 in corn-wheat-soybean meal-based diet improved growth performance of broilers through improving antioxidant capacity, immunity, and digestive enzyme activity. Based on the results of this study, 1.1-1.6 × 10(9) CFU/kg BA-5940 is recommended for supplementation in broiler diets.