Abstract

Antibiotic-resistant bacteria are prevalent in husbandry around the world due to the abuse of antibiotic growth promoters (AGPs); therefore, it is necessary to find alternatives to AGPs in animal feed. Among all the candidates, probiotics are promising alternatives to AGPs against Salmonella infection. The anti- Salmonella effects of three probiotic strains, namely, Lactobacillus crispatus 7–4, Lactobacillus johnsonii 3–1, and Pediococcus acidilactici 20–1, have been demonstrated in our previous study. In this study, we further obtained the alginate beads containing compound probiotics, namely, microencapsulate probiotics (MP), and evaluated its regulatory effect on the health of broilers. We incubated free and microencapsulate probiotics in simulated gastric and intestinal juice for 2 h, and the results showed that compared to free probiotics, encapsulation increased tolerance of compound probiotics in the simulated gastrointestinal condition. We observed that the application of probiotics, especially MP, conferred protective effects against Salmonella typhimurium ( S.Tm ) infection in broilers. Compared to the S.Tm group, the MP could promote the growth performance ( p  < 0.05) and reduce the S.Tm load in intestine and liver ( p  < 0.05). In detail, MP pretreatment could modulate the cecal microflora and upregulate the relative abundance of Lactobacillus and Enterobacteriaceae . Besides, MP could reduce the inflammation injury of the intestine and liver, reduce the pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) expression, and induce of anti-inflammatory cytokine (IL-10) expression. Furthermore, MP could inhibit NLRP3 pathway in ileum, thereby attenuating S.Tm -induced inflammation. In conclusion, MP could be a new feeding supplementation strategy to substitute AGPs in poultry feeding.