Effects of rhamnolipids on growth performance, gut barriers, antioxidant capacity, immune function, and gut microbiota in broiler chickens.

This study aimed to investigate the effects of dietary supplementation of rhamnolipids (RLS) on growth performance, gut morphology, antioxidant function, lipid metabolism, immune responses, and gut microbiota in Linnan yellow-feathered broilers. A total of 390 one-day-old broilers were randomly assigned to three groups: Control (CON), 250 mg/kg RLS (RLS250), or 500 mg/kg RLS (RLS500). The broilers were fed with basal diet, or basal diet supplemented with 250 or 500 mg/kg RLS for 56 days. Each treatment contained 10 replicates with 13 chickens per replicate. Results showed that diet supplemented with RLS250 and RLS500 markedly improved final BW and ADG on day 56. RLS reduced the CD and increased the VH/CD of jejunum and ileum. RLS significantly increased the levels of total T-AOC and GSH-Px on day 28, while the levels of T-AOC and SOD were higher than CON groups on day 56. RLS treatment also regulated the lipid metabolism in the broilers by increasing the concentration of serum HDL-C and decreased LDL-C. The levels of serum immunoglobulins including IgA, IgM and IgY in RLS250 and RLS500 groups were notably higher than those of CON groups on day 56. Meanwhile, ileum IgA and IgM in RLS500 groups were evidently higher than other two groups. RLS significantly increased the level of IL-10. RLS showed no significant effects on VFA in cecum of broilers. Results of 16S rRNA sequencing showed that RLS optimized the microbiota by lowering the relative abundance of Anaerofilum and DUT089, and regulating g__norank_f__ Ruminococcaceae. This study found that supplemented with RLS in diet improved the growth performance, antioxidant function, and immune function, and regulated intestinal microbiota of broilers, revealing that RLS is potential feed additive for use in animal husbandry.