Abstract: To investigate the effect of multi-strain co-fermented feed on resisting Salmonella infection in broilers, 50 one-day-old broilers were randomly divided into 5 groups and were fed with different feeds: control group (basal diet+10% unfermented feed), model control group (basal diet+10% unfermented feed), antibiotic control group (basal diet+10% unfermented feed+20 mg·kg^-1 colistin sulfate), 5% fermented group (basal diet+5% unfermented feed+5% fermented feed), 10% fermented feed (basal diet+10% fermented feed). Oral administration of 400 μL Salmonella(1 × 10⁹ CFU·mL^-1) for two days except the control group when the broilers were 13 days old, the control group was given equal volume of sterile water. The broilers were slaughtered at the age of 15 days. Serum levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), endotoxins (LPS) and D-lactic acid (D-LA) were measured. Got colon for HE staining was to observe the shape of colon and got cecum mucosa was to determine the mRNA expression of TLR4 pathway key signaling molecules. The results showed that salmonella infection resulted in a significantly increase level of serum pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α).The mRNA expression of TLR4 signal pathway key signaling molecules (TLR4, MyD88, TRAF6, NF-κB) increased significantly. The level of serum LPS and D-LA increased significantly. While the indexes of antibiotic control group, 5% fermented group, and 10% fermented group were improved to some extent, indicating that the multi-strain co-fermented feed can ameliorate the intestinal inflammation and intestinal barrier destruction that caused by Salmonella infection. The effect was close to 20 mg·kg^-1 colistin sulfate.

Key words: multi-strain co-fermented feed, broiler, Salmonella, anti-infection