Immunomodulatory effect of β-glucans in broiler chickens challenged with E. coli.

Introduction: In Colombia, poultry farming is one of the main livestock activities in the country and with this it becomes fundamental to perform a correct antibiotic management in production, since antimicrobial resistance is considered an emerging problem. Understanding this, β-glucans have been considered an alternative to antibiotics. Objective: An experiment was carried out to evaluate: How do β-glucans generate an immunomodulatory effect in broilers, since studies show that they can promote bird growth, provide immunomodulatory effects and prevent antimicrobial resistance. Methods: 150 one-day-old Broiler Ross line birds challenged at 7 days of age with oral inoculation of E. coli (1·107 CFU) via gavage were used. The β-glucan additive was supplied in drinking water, and the treatments were T1: 0.1% saline, T2: β-glucan 0.25%, and T3: β-glucan 0.5%. Eight birds from each treatment were randomly selected on days 17, 21 and 43 of age, and blood samples were collected to determine the levels of immunoglobulins (IgG, IgA, IgM). Subsequently, they were sacrificed and organs were collected: thymus, spleen and bursa of Fabricius - to determine the relative weight of the thymus and the size of the bursa and spleen. Results and Discussion: After determining globulins on day 17 of life (10 days post-infection: DPI) no significant differences were obtained; on day 21 (14 DPI) (P=0.0008) and day 43 (35 DPI) (P= <0.0001) the highest IgG value was obtained with T2. Likewise, measurement of lymphoid organ size at 10 DPI showed significant increases in bursa (P=0.003) and spleen (P=0.03) with T2; at 14 DPI, T2 increased bursal size (P= 0.015); and finally, at 35 DPI, bursal size (P=0.007) and relative thymus weight (P=<0.0001) increased with T1, while spleen increased in size with T2. Delivery of β-glucan at 0.25% (T2) influences the immune response by increasing the amount of IgG in the late phase of infection, and the increase in the size of the bursa and spleen influences the immune response against infection. Conclusion: The use of β-glucans at 0.25% is a viable alternative to improve the immune response in E. coli positive birds. [ABSTRACT FROM AUTHOR]