Effects of a direct fed microbial and xylanase enzyme blend on Salmonella Typhimurium colonization, antioxidant status, and performance in broiler chickens

Salmonella is a major issue in the poultry industry, with infected flocks causing contaminated carcasses and products leading to outbreaks. Blends of enzymes and direct fed microbials (DFMs) have shown potential to reduce Salmonella colonization in broilers. This study investigated the effects of supplementing DFMs and enzyme blends under low-energy nutritional status and S. Typhimurium challenge on performance, Salmonella colonization and prevalence, and antioxidant status of broilers. A total of 256 day-old broiler chicks were randomly allocated to four dietary treatment groups (8 birds/cage, 8 replicate cages) and fed a standard energy diet as positive control (PC; 2,975 kcal/kg ME), a reduced energy diet as negative control (NC; 2,875 kcal/kg ME), the NC diet supplemented with a Bacillus spp. probiotic and xylanase blend (EFS), or the NC diet supplemented with a blend of multi-species probiotic and xylanase (BAX). Performance parameters were measured per cage on d 0, 7, 17, and 28. All birds were challenged with 1 × 10⁷ CFU/mL of S. Typhimurium on d 7. On d 7, 10, 17, and 28, liver samples were collected to evaluate the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), as well as the malondialdehyde (MDA) content. On d 10, 17, and 28, the ceca and liver were collected (8 birds/group) to measure Salmonella colonization and prevalence, respectively. EFS and BAX had significantly greater BW on d 17, and higher BWG and enhanced FCR on d 7-17 compared to NC. EFS and BAX had a 1.70 and 1.61 log reduction of Salmonella in the ceca, respectively, compared to NC on d 10. BAX had lower (P < 0.05) catalase activity compared to NC on d 10 and d 17; and EFS and BAX had lower (P < 0.05) MDA content compared to PC on d 28. Addition of DFMs and xylanase blends to a low energy diet reduced Salmonella colonization in the ceca and improved performance and antioxidant status of broilers.