Study suggests EnzaPro additive could reduce Salmonella Heidelberg cecal colonization from direct exposure or horizontal infection by modulating immune response in broiler chickens

Supplementing broilers with EnzaPro, a feed additive formulated with a unique combination of direct fed microbials and xylanase, could decrease Salmonella colonization in birds, according to research shared at the Poultry Science Association (PSA) annual meeting held July 11-14 in San Antonio, Texas. EnzaPro is an enzyme additive marketed by BioResource International (BRI).

The oral presentation detailed the research which analyzed the effect of 4 dietary treatments on Salmonella Heidelberg colonization and immune response of broiler chickens’ when raised up to 28 days in new litter floor pen. The study included a total of 400, one-day old Ross 708 male chicks randomly distributed into the 4 dietary treatments with 100 chicks per treatment in challenged setup. The dietary treatments include a standard control (C; no additives corn- SBM based mash feed), antibiotic growth promoter (AGP; Enramycin 10 ppm), EnzaPro (C+ EnzaPro; EP), and EP with 75 kcal/kg reduced metabolizable energy (ME) compared to control (C+ EnzaPro - 75kcal/kg; EP-75). The reason EnzaPro was utilized with/without energy reduction was due to xylanase in EP having a nutrient matrix of 75kcal/kg as well as tested for “on top” effect of EP against Salmonella colonization.

On day 3, 20% of the birds were orally gavage with 0.5 mL of 10⁸ CFU/mL of Salmonella Heidelberg (seeders) and remaining 80% were considered non-seeder which got infected horizontally from seeders. Ceca were collected on days 7, 14, 21, and 28 of age from non-seeder birds, and 14 and 28 d of age for seeder birds. Blood samples were also collected on d 14 and 28 for immune cell profile as well as phagocytic cells. Salmonella colonization data was log transformed whereas immune cell parameters were obtained using flow cytometry and presented as %. Tukey’s test was done to compare means where significance declared at P< 0.05.

The results showed that on d 14 in seeder group all the challenged birds were positive for Salmonella regardless of treatment group, whereas by d 28, 50-60% of the birds fed EP either on top or reduced energy recovered from Salmonella compared to 40% in control. Similar pattern was seen in non-seeders fed EP with 70% birds recovered from infection compared to 45% in control by d 28.

Phagocytic cells results shows that there was no difference in monocytes but heterophils tends to decrease in EP-75 group. This could be related to early reduction of Salmonella count in this group. However, T helper cells in blood circulation as well as targeted toward mucosa was higher in EP fed birds which could further stimulate IgA production to bind pathogen and prevent from colonization.

Naive cytotoxic T cells had tendency to reduce (P < 0.08) in AGP group compared to control as AGP directly work with pathogen in gut whereas activated cytotoxic T cells was lowest in EP75 group which could be related to reduce Salmonella in that group. Similar results were also seen for C- reactive protein with reduction in EP-75.

The researchers concluded from these results that blend of direct fed microbial and enzyme (EnzaPro) may decrease Salmonella colonization in ceca of directly infected birds as well as horizontally infected birds. This study also provide insight into potential role of EP to enhance the adaptive immune system via T helper cells which regulates IgA in intestinal mucosa leading to decrease in Salmonella colonization in broilers.

BRI researcher Dr. Sudhir Yadav states, “This study confirmed that direct-fed microbial and xylanase blend is an effective technology to reduce immune cost by modulating immune cells depending on pathogen presence as well as its load. Including EnzaPro in the diet did reduce colonization and horizontal transmission to improve recovery from Salmonella infection. Further studies can be done with EnzaPro.”