Effects of modified corn straw dietary fiber on antioxidant status, gut health and lipid metabolism in broilers fed a high-fat diet.

Hepatic abnormal fat accumulation may induce metabolic dysfunction, whereas dietary fiber is proven to reduce body fat deposition. Corn straws, rich in lignocellulose, are a potential source of dietary fiber. This study explored the effects of modified corn straw dietary fiber (MCDF) on broilers fed a high-fat diet and its regulatory mechanisms in lipid metabolic disorders. A total of 150 one-day-old Arbor Acres (AA) broilers were randomly assigned to three experimental groups: control group (basal diet), group 1 (high-fat diet), and group 2 (high-fat diet supplemented with 1% MCDF). The feeding trial was divided into two phases: the early stage (1 to 21d) and the later stage (22 to 42 d). Results showed that groups 1 and 2 exhibited significantly higher ADG and ether extract (EE) metabolism rate at 21 d compared to control group (P < 0.01), whereas feed/gain (F/G) and CP metabolism rate were reduced (P < 0.01). At 42 d, group 2 exhibited a lower F/G compared to the other groups (P < 0.001). MCDF decreased serum levels of TC, TG, ALP, and MDA (P < 0.05), whereas elevated the serum levels of CAT, GSH-Px, IgA, and IgM (P < 0.05). Multi-omics analysis revealed that MCDF reshaped the gut microbiota by increasing the abundance of beneficial taxa (Bacteroidota and Bacteroides) and reducing potentially harmful bacteria (Campylobacterota). These microbial changes were associated with alterations in serum metabolites (arachidonic acid, DHA, DPA, EPA). Furthermore, changes in these metabolites were involved in the regulation of hepatic lipid metabolism by modulating cytochrome P450-related pathways, amino acid metabolism, and key regulatory genes including CYP450, CYP7A1, LTC4S, and PPARα. In conclusion, MCDF alleviated high-fat diet-induced hepatic lipid metabolic disorders through the gut microbiota-metabolite-liver axis. These findings suggest that MCDF, as a functional dietary fiber, has potential applications for improving metabolic health in broilers.