Evaluation of a prebiotic mannan-oligosaccharide on Salmonella Enteritidis cecal colonization and immune response of broiler chickens

Authors: MILBY-BLACKLEDGE, ALLISON - Texas A&M University; FARNELL, YUHUA - Texas A&M University; Swaggerty, Christina; FARNELL, MORGAN - Texas A&M University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2025
Publication Date: 10/1/2025
Citation: Milby-Blackledge, A., Farnell, Y., Swaggerty, C.L., Farnell, M. 2025. Evaluation of a prebiotic mannan-oligosaccharide on Salmonella Enteritidis cecal colonization and immune response of broiler chickens. Poultry Science. 104(12). Article 105931. https://doi.org/10.1016/j.psj.2025.105931.
DOI: https://doi.org/10.1016/j.psj.2025.105931

Interpretive Summary: Salmonella causes 1.35 million cases of foodborne illness in the United States annually, and poultry are one source of contamination. The poultry industry is looking for alternative approaches to reduce the burden of Salmonella in poultry. Prebiotics are compounds found in food that have been shown to help good bacteria grow in the gut which could limit the growth of bad bacteria such as Salmonella. The objectives of this study were to determine if feeding various levels of a prebiotic to chickens will lessen the numbers of Salmonella by boosting the birds’ immune response. Samples were collected to count the numbers of SE, and blood was collected to measure the immune response. To measure the immune response, we measured cytokines and antibody production, which are both proteins responsible for coordinating an effective immune response and would be important for reducing SE in the birds. The experiment was conducted two times. In both experiments, feeding birds the higher doses of the prebiotic significantly reduced the numbers of SE. We also found changes at the immune response level. A cytokine, MIP, was reduced in the birds on the prebiotic supplement as well as an antibody (IgM). Decreases in these two proteins suggests the prebiotic is reducing inflammation and antibody production. Reducing inflammation in the chicken gut (where Salmonella grow) will keep the gut healthier and therefore less likely to be colonized by SE which is what we saw with the lower numbers of SE in the birds on the prebiotic treatment. Feeding chickens a diet supplemented with a prebiotic is a potential alternative approach to reduce the numbers of Salmonella in the chicken and may contribute to creating a safe and wholesome product for the consumer.

Technical Abstract: Salmonella causes 1.35 million cases of foodborne illness in the United States annually. We hypothesized that the administration of ActiveMOS®, a prebiotic mannan-oligosaccharide (MOS) product, will reduce Salmonella Enteritidis (SE) cecal colonization and improve immune function in young broilers. The objectives of this study were to assess the effects of MOS on SE cecal colonization, serum cytokines, lipopolysaccharide (LPS) and immunoglobulin M (IgM) expression. This study consisted of two replicate 14-day trials. Day-of-hatch broilers (n = 240) were evenly distributed across eight floor pens where they were randomly assigned into four treatments. Treatments were as follows: control (0.0), 1.0, 1.5, and 2.0 kg of MOS/metric ton (MT) of feed. Broilers were orally gavaged with SE at 7 days of age. Birds were euthanized one week post infection. Cecal colonization, serum pro-inflammatory cytokines- interferon gamma (IFN'), interleukin-2 (IL-2), IL-6, IL-16, IL-21;anti-inflammatory/regulatory cytokines- IFNa, IL-10; chemokines- regulated on activation, normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein-1ß (MIP-1ß), MIP-3a; colony-stimulating factors- macrophage colony-stimulating factor (M-CSF); and growth factors- vascular endothelial growth factor (VEGF), IgM titers, and LPS concentrations were evaluated. Data were analyzed via a one-way ANOVA with an a = 0.05. In the first replicate, Salmonella was significantly reduced (p < 0.0001) by 0.87 and 0.83 log in the 1.5 kg/MT and 2.0 kg/MT inclusions, respectively. In replicate two, a significant 1.26 log reduction (p = 0.0161) of SE in the 1.5 kg/MT diet was observed. Decreased expression of MIP-1ß was detected in the challenged 1.0 kg/MT and 2.0 kg/MT (p = 0.0163) diets. No significant differences were observed with any other cytokines or LPS. The isotype IgM was reduced (p = 0.0066) in the 0.0 kg/MT diet compared to all other treatments, suggesting depressed humoral immunity or a decline in inflammation. Although a mechanism of action was not determined, these data suggest that MOS at the 1.5 kg/MT inclusion was efficacious in reducing SE.