Effects of dietary L-Citrulline or L-arginine supplementation on immune function, intestinal morphology and...

This study aimed to investigate the effects of dietary L-citrulline (L-Cit) or L-arginine (L-Arg) supplementation on jejunal mucosal barrier function and inflammatory response in broilers under lipopolysaccharide (LPS) challenge. A total of 384 one-day-old yellow-feathered broilers were randomly divided into 4 groups with 8 replicates per group and 12 birds per replicate. The control group and LPS group were fed a basal diet, while the L-Cit group and L-Arg group were supplemented with 1% L-Cit and 1% L-Arg in the basal diet, respectively. The experiment lasted for 27 days. On days 22, 24, and 26 of the experiment, broilers in the control group were intraperitoneally injected with 1 mg/kg body weight of saline, while those in the LPS group, L-Cit group, and L-Arg group were intraperitoneally injected with 1 mg/kg body weight of LPS. The results showed that no significant effect on growth performance of 21d broilers was observed among all groups (P > 0.05). Both the L-Cit group and L-Arg group significantly or extremely significantly increased the levels of T-AOC, SOD, IgG, and IgM (P < 0.05 or P < 0.01), and significantly decreased the levels of IL-6 and TNF-α (P < 0.05 or P < 0.01). Hematoxylin-eosin staining and immunofluorescence analysis revealed that L-Cit alleviated intestinal villus atrophy and enhanced intestinal barrier integrity induced by LPS challenge. Notably, both L-Cit and L-Arg regulated the structure of the intestinal microbial community. L-Arg primarily promoted the abundance of beneficial bacteria such as g_Faecalibacterium and g_Barnesiella, whereas L-Cit significantly promoted g_Akkermansia to become the dominant genus and exert its function.