| Abstrakt: |
The objective of this study was to investigate the effects of dietary Bacillus subtilissupplementation on growth performance, jejunal lesion scores, oocyst shedding, and cytokine and tight junction protein expression in broiler chickens infected with Eimeria maxima. A total of 196 male day-old Ross 708 broilers were given a nonexperimental diet until 14 D of age. Then, all chickens were randomly assigned to one of seven dietary treatments: 2 basal diets (CONand NC); CON + virginiamycin (AB1); CON + bacitracin methylene disalicylate (BMD; AB2); CON + B. subtilis1781 (PB1); CON + B. subtilis747 (PB2); or CON + B. subtilis1781 + 747 (PB3). At day 21, all chickens except those in the CON group were orally inoculated with E. maximaoocysts. At 7 D after E. maximainfection, the body weight gains of chickens fed PB2 and PB3 increased (P = 0.032) as much as those in chickens fed AB2. The body weight gain and feed efficiency of chickens fed PB2 were significantly increased (P < 0.001), and PB2 chickens showed (P = 0.005) the lowest lesion scores after E. maximainfection. Chickens fed PB2 showed (P < 0.05) lower mRNA expression of IL-1β in infected chicken groups. Chickens in the AB1, AB2, PB1, PB2, and PB3 groups showed (P < 0.05) greater mRNA expression of junctional adhesion molecule 2 in jejunal tissue, whereas occludin expression increased (P < 0.05) in the jejunal tissue of chickens fed AB2 or PB2. Dietary B. subtilissupplementation significantly improved the growth performance of young chickens to a level comparable with that induced by virginiamycin or BMD without E. maximainfection. After infection with E. maxima, dietary virginiamycin and BMD significantly enhanced the epithelial barrier integrity, and the dietary B. subtilis747 showed significantly enhanced growth performance, intestinal immunity, and epithelial barrier integrity. Together our results indicated that certain strains of B. subtilisprovide beneficial effects on the growth of young broiler chickens and have the potential to replace antibiotic growth promoters. |
