Effect of Dietary Bacillus Subtilis C14 and RX7 Strains on Growth Performance, Blood Parameter, and Intestinal Microbiota in Broiler Chickens Challenged with Salmonella Gallinarum

Sixty broilers (initially 1.6 kg and 35 d-old) were used to determine the effect of Bacillus subtilis C14 and RX7 strains on growth performance, blood parameter, and intestinal microbiota in response to experimental challenge with Salmonell gallinarum. Broilers were distributed to 4 treatment groups include: C1 (control group; no challenge, no B. subtilis), C2 (Salmonella-challenged group; S. gallinarum 10(8) cfu/bird), T1 (C2+supplemented with of B. subtilis C14 (1.0×10(9) cfu/g) at 0.1% in diet) and T2 (C2+supplemented with of B. subtilis RX7 (1.0×10(9) cfu/g) at 0.1% in diet). Results indicated that inclusion of B. subtilis (T1, T2) in the diet increased (P<0.05) the weight gain and feed intake, and improved feed conversion of challenged broilers compared with no B. subtilis supplementation diet (C2). Improvements (P<0.05) in the immunoglobulin A concentration were observed by the addition of B. subtilis compared with C2 treatment, whereas tumor necrosis factor-α was decreased (P<0.05). Latobacillus number in small and large intestines was higher (P<0.05) by B. subtilis additon than C2 treatment but Salmonella numbers were lower (P<0.05). The results suggested that dietary supplementation of B. subtilis C14 and RX7 improved the growth performance, and affected the blood profiles and intestinal microbiota of broilers against S. gallinarum infection. Therefore, B. subtilis C14 and RX7 may have beneficial effects, in relieving the stress of broilers infected with S. gallinarum.