Fucoidan-rich Ecklonia radiata supplementation improves growth performance, immune responsiveness, and gut health in pigs

Benefiting from the great variety of bioactive compounds, brown seaweeds offer promising possibilities for animal nutrition. However, limited research has explored the potential of brown seaweed species in livestock production. This study investigated the effects of dietary supplementation with Ecklonia radiata on growth performance, immune responses, gut morphology, and microbiota in pigs. Twenty pigs were allocated into three groups: control (basal diet, n = 8), low-dose supplementation (5 g/kg basal diet; n = 6), and high-dose supplementation (15 g/kg basal diet; n = 6) of E. radiata provided via top-dressing. The supplementation of E. radiata had significantly promoted the average daily gain (ADG; p < 0.05) and feed conversion efficiency (FCE; p < 0.05) compared with control. Histomorphological analysis revealed that the seaweed supplementation had significantly increased the villus height in the duodenum (p < 0.01), jejunum (p < 0.05), and ileum (p < 0.05). Splenocyte proliferation was significantly higher in both supplemented groups than in controls (p < 0.001). Short-chain fatty acids (SCFA) production was significantly elevated in the supplemented groups at the end of the experiment (p < 0.05). Gut microbiota profiling revealed increased α-diversity (Shannon entropy; p < 0.01) in the low-dose group, alongside enrichment of SCFA-producing taxa, such as Ruminococcus, Anaerostipes, and Phascolarctobacterium. In summary, E. radiata supplementation improved pig growth performance and cellular immune responsiveness, potentially mediated by enhanced intestinal morphology and modulated gut microbiota. These findings highlight the potential of Australian brown seaweeds as functional feed additives to support sustainable animal nutrition and health.