The aim of this study was to investigate the alleviating effects of different dietary levels of Bifidobac-terium on ileum injury of goslings under lipopolysaccharide(LPS)stress.A total of 288 one-day-old male Jiangnan white goose chicks were randomly divided into 6 groups with 6 replicates per group and 8 chicks per replicate.A 3×2 two-factor design was adopted,and the two factors were Bifidobacterium supplemental level(0,300 and 600 mg/kg Bifidobacterium freeze-dried powder was supplemented,and the effective viable bac-teria number was 1.7×1010 CFU/g,respectively)and LPS stress or not(intraperitoneal injection of LPS saline solution or saline solution,and the concentration of LPS saline solution was 0.5 mg/mL).The experiment las-ted for 28 days,and the goslings were intraperitoneally injected with 1 mL/kg BW on the 15th,17th and 19th days of the experiment,respectively.The results showed as follows:1)LPS stress significantly increased the diamine oxidase(DAO)activity and the D-lactic acid(D-LA)content in serum of goslings(P＜0.05);Bifidobacterium supplementation significantly reduced the DAO activity and the D-LA content in serum of gos-lings(P＜0.05).2)LPS stress significantly increased the ileum injury score of goslings and had a significant effect on mucin 2(MUC2)content in ileum(P＜0.05);Bifidobacterium supplementation significantly re-duced the ileum injury score and increased the MUC2 content in ileum(P＜0.05).3)Compared with the sup-plementation of 300 mg/kg Bifidobacterium,the supplementation of 600 mg/kg Bifidobacterium significantly decreased the D-LA content in serum and significantly increased the MUC2 content in ileum of goslings at 28 days of age(P＜0.05),but there were no significant differences in the indices at other days of age(P＞0.05).4)LPS stress could cause serious injury of gosling's ileal epithelial cells,with obvious cytoplasm edema,ap-proximately irregular oval nucleus,expansion of Golgi capsule membrane,overall structural damage of mi-crovilli,and fuzzy structure of tight junctions and intermediate junctions between cells.Bifidobacterium was in-volved in alleviating the above phenomenon by inducing autophagy and helping to protect mitochondrial struc-ture.In addition,300 mg/kg Bifidobacterium freeze-dried powder could significantly alleviate cytosolic edema and rough endoplasmic reticulum dilation.In conclusion,LPS stress of goslings aged from 1 to 28 days can cause damage to the ileum and ileal epithelial cells,result in abnormal secretion of MUC2 and increase intesti-nal permeability.Dietary Bifidobacterium can alleviate ileum injury and improve intestinal permeability by pro-moting MUC2 secretion,and can alleviate ileal epithelial cell injury by inducing autophagy.Under the condi-tions of this experiment,the supplementation of 600 mg/kg Bifidobacterium freeze-dried powder in the diet could not achieve better relief effects,so the supplementation of 300 mg/kg is recommended.[Chinese Jour-nal of Animal Nutrition,2024,36(5):3035-3048]
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