ARTICLE 66 FEED & ADDITIVE MAGAZINE December 2022 Similar results were seen in a turkey trial where administration of the postbiotic led to a significantly higher abundance of firmicutes and actinobacteria in the supplemented group compared to the control in the feces after 21 days. Additionally, the microbiota of the treated animals was characterized by a lower abundance of Proteobacteria, attributed to the class of Gammaproteobacteria (mainly Enterobacteriaceae such as Klebsiella, Shigella, Acinetobacter, Escherichia, Enterobacter, Erwinia and Serratia). After 85 days, the supplemented group exhibited higher abundance of health promoting species such as Lactobacillus, Clostidium bifermentans and Pediococcus acidilactici (Zampiga – WPC 2020)(Figure 6). PATHOGEN PREVENTION The decrease in Enterobacteriaceae could partially be explained by the composition of the yeast postbiotic due to the presence of the α-mannans who will adhere to type-1 fimbriae of pathogenic bacteria including Salmonella, making it more difficult for these pathogens to colonize the intestinal epithelium (Posadas et al., 2017) (Figure 2). This is confirmed in a Salmonella Typhimurium challenge model where administration of Safmannan® reduced the Salmonella colonization in ceca (P=0.001) on D28 of the trial. A reduced colonization of Salmonella in the liver (P=0.038) also indicates that an increased intestinal health reduced the translocation of the pathogen to systemic organs (data on file) (Figure 7). VACCINE POTENTIATION Within the lamina propria of the gut, there is a sophisticated immune system further protecting the host from infectious diseases. The gut associated lymphoid tissue (GALT) plays a major role in the gut immune response including both innate and adaptive functions. The GALT includes organized lymphoid structures such as the bursa of Fabricius, cecal tonsils, Peyer’s patches, Meckel’s diverticulum and lymphocyte follicles. Although the GALT in newly hatched chicks is quite underdeveloped, a fully functional immune system is formed within 4 weeks after hatch. Enterocytes express pattern recognition receptors (PRRs) which sense conserved pathogen molecular signatures while remaining non-responsive to the commensal microbiota. As a consequence, various immune pathways to initiate microbial killing are activated. Additionally, enterocytes secrete a large variety of antimicrobial peptides into the intestinal lumen and plasma cells are secreting IgAs to neutralize pathogens and facilitate their removal from the gastro-intestinal tract (Kogut et al., 2017; Wickramasuriya et al., 2022). In order to modulate the immune system and improve intestinal health, β-glucans derived from yeast have shown to be very efficacious. β-glucans from yeast are natural polysaccharides consisting of a Figure 6. The feces of turkeys in the Safmannan group showed a higher abundance of health promoting microorganisms in comparison to the control group. Figure 7. Salmonella colonization in ceca was significantly reduced in the Safmannan group
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