Clostridium butyricum (C. butyricum) is increasingly being used to test the promotion of the gut health of animals. However, the modes of action for such applications for waterfowl remain unclear. Thus, we investigated whether or not intestinal barrier function, immune-related gene expression, and the diversity of the intestinal microbiota in Pekin ducks varied under C. butyricum supplementation. A total of 500 ducks were randomly assigned into five treatments supplemented with basal diets containing: either 0 (group Control), 200 (group CB200), 400 (group CB400) and 600 (group CB600) mg/kg C. butyricum or 150 mg/kg aureomycin (group A150) for 42 days. In comparison with the control group, C. butyricum supplementation enhanced the growth performance and intestinal villus height of Pekin ducks at 42 d. Serum immune indexes and fecal short-chain fatty acids (SCFAs) were all improved at both 21 d and 42 d after C. butyricum addition. The mRNA expression levels of Mucin2, Zonula occludens-1 (ZO-1), Caudin-3, and Occludin increased at 21 d and 42 d and the mRNA expression levels of IL-4 and IL-10 only increased at 42 d after C. butyricum addition. Dietary C. butyricum also resulted in an increase in the number of diversities of operational taxonomic units (OTUs), and an increase in the α-diversity of intestinal microbiota. The addition of C. butyricum altered the composition of the intestinal microbiota from 21 d to 42 d. The relative abundance of Firmicutes and Bacteroidetes showed little changes among groups; however, the relative abundance of Firmicutes/Bacteroidetes were found to have been significantly different between the 21 d and 42 d. C. butyricum administration improved the intestinal health of Pekin ducks by increasing the diversity of intestinal microbiota, enhancing the SCFAs contents, and strengthening the intestinal barrier function and immune systems. The optimal dietary supplementation dosage was recommended as 400 mg/kg in the diet.

Clostridium butyricum (C. butyricum) can attenuate oxidative stress, inflammation, and hepatic fatty deposition in poultry, however, the underlying mechanisms for this in Pekin ducks remain unclear. This study evaluated these hepatoprotective effects and the underlying mechanisms in a corticosterone (CORT)-induced liver injury model in Pekin ducks fed a C. butyricum intervention diet. A total of 500 Pekin ducks were randomly divided into five groups: one group (CON group) was only provided with a basal diet, three groups were provided a basal diet with 200 mg/kg (LCB group), 400 mg/kg (MCB group), or 600 mg/kg (HCB group) C. butyricum, respectively, and one group was provided a basal diet with 150 mg/kg aureomycin (ANT group) for 42 d. At 37 days-old, all ducks received daily intraperitoneal injections of CORT for five days to establish a liver injury model. C. butyricum intervention alleviated liver injury by decreasing the liver organ indices, hepatic steatosis and hepatocyte necrosis, and improving liver function, antioxidant capacity, and inflammatory factors. Hepatic RNA-seq revealed 365 differentially expressed genes (DEGs) between the MCB and CON groups, with 229 up- and 136 down-regulated DEGs in the MCB group. Between the MCB and ANT groups, 407 DEGs were identified, including 299 up- and 108 down-regulated genes in MCB group. Some DEGs in the MCB group related to oxidative stress and inflammatory responses such as Sod3, Tlr2a/b, and Il10, which were up-regulated, while Apoa1, Cyp7a1, Acsl1/5, Fasn, Ppar-γ, and Scd, which are involved in lipid metabolism, were down-regulated, indicating that these genes were responsive to dietary C. butyricum for the alleviation of corticosterone-induced hepatic injury. Toll-like receptor signaling, PI3K-Akt signaling pathway, cytokine-cytokine receptor interaction, peroxisome proliferator-activated receptor (PPAR) signaling pathway, adipocytokine and glycerophospholipid metabolism signaling pathway were significantly enriched in the MCB group. These findings indicate that C. butyricum intervention can protect Pekin ducks from corticosterone-induced liver injury by the modulation of immunoregulatory- and lipid metabolism-related genes and pathways.

This study aimed to explore the protective mechanism of silybin against heat stress-induced liver injury in Peking ducks as a result of oxidative stress, inflammation, and lipid metabolism. One hundred and ninety-five 1-day-old healthy male Peking ducks with similar body weights were randomly divided into a control group, a heat-stress group, and three intervention groups treated with 400, 800, and 1600 mg/kg silybin under heat-stress from 21 d to 35 d for two weeks. The function indices, oxidative stress, inflammatory factor levels, histopathological changes and non-targeted lipidomic profiling in liver as well as growth performance were evaluated. Results showed that silybin supplementation partially alleviated the heat-stress-induced decreases in average daily feed intake and body weight gain (p > 0.05). Silybin supplementation at 400 and 800 mg/kg significantly reduced the heat-stress-induced increases in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyl transpeptidase (γ-GGT) (p < 0.05), whereas the effect of 1600 mg/kg silybin was not significant. Albumin (ALB) and globulin (GLB) levels were mainly improved in the 800 mg/kg group, and GLB was also increased in the 400 mg/kg group (p < 0.05). Silybin supplementation significantly improved hepatic antioxidant capacity, especially in the 400 and 800 mg/kg groups, as indicated by increased superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC), and decreased malondialdehyde (MDA) and reactive oxygen species (ROS) levels (p < 0.05). In addition, the 400 and 800 mg/kg groups showed more significant reductions in the pro-inflammatory factors IL-6 and TNF-α, while IL-10 was increased in silybin-supplemented groups (p < 0.05). Lipid metabolism disorders were improved through regulation of the sphingolipid and glycerophospholipid metabolism pathways, while it alleviated heat stress damage by reducing the expression of heat shock proteins. In conclusion, silybin holds promise as an effective feed additive to alleviate heat stress in poultry. This study provides a theoretical basis and practical approach for improving the health and productive performance of Peking ducks under heat-stress conditions.