Administration of yeast fraction reduces outcome of Salmonella Typhimurium challenge on broilers

In recent years, the market positioning for a reduction on antibiotic use in animal production gained strength with a focus to produce antibiotic free livestock. In this context mannan-oligosaccharides (MOS) have conquered the animal health industry. MOS could function as potential alternatives in a strategy for antibiotic reduction and substitution and help the animals to maintain their productive potential. Yeast fractions are rich in mannoproteins, mannans and β-glucans, enabling them to modulate the gut physiology. The occurrence of β-glucans allows them to modulate the immune system, while the presence of mannans can associate them with bacteria possessing type-1 fimbriae, such as Salmonella.

Therefore, the objective of this study was to evaluate the effect of the supplementation of a premium yeast fraction on Salmonella colonization in broilers.

At day 1 of the trial, newly hatched broiler chicks were divided over 3 isolators, each representing one treatment group; (1) the unchallenged control, (2) the challenged control and (3) yeast fraction supplemented and challenged group. At day 2, animals in the challenged control and the yeast fraction group were orally inoculated with 10⁸ CFU of Salmonella Typhimurium ATCC 14028. Individual body weights were recorded at days 3, 7, 14 and 28. Immune parameters, histology scores and Salmonella Typhimurium loads in crop, liver and spleen were determined at days 14 and 28. Challenge with Salmonella Typhimurium reduced body weights in the challenged control group in some dates. Additionally, the challenged control exhibited significantly increased Salmonella Typhimurium numbers in crop, liver and caecum compared to the negative control group, which remained negative for Salmonella throughout the experiment. The study also demonstrated the efficacy of the premium yeast fraction in decreasing the adverse effects of Salmonella infection on broilers. The yeast fraction was able to improve the performance of the challenged animals, while decreasing the lesion score in the cecum and the Salmonella colonization in liver and ceca. The results also demonstrated the effect of the yeast fraction on the immune system, since supplemented birds were able to produce higher antibody titers of IgA against salmonella LPS and flagellin.

Key Words: Salmonella, yeast fraction