Alfalfa Polysaccharide Improves Rabbit Growth by Modulating Gut Microbiota and Suppressing Inflammation Through PPARγ/NF-κB Pathway

Meat rabbits are ideal meat-producing animals. However, weaning-induced intestinal inflammation often leads to growth delays, and severe cases impair breeding efficiency. Alfalfa polysaccharides (APSs) have antioxidant and anti-inflammatory properties, making them potential natural alternatives to antibiotics. To date, relatively limited research has been conducted on APS in meat rabbits. This research investigated the effects of APS on growth performance, intestinal inflammation, and meat quality in rabbits. Eighty healthy rabbits were randomized into four treatment groups, each group consisting of five replicates, with four rabbits per replicate. The four experimental groups were the control group (CON, basal diet), 400 mg/kg APS group (basal diet + 400 mg/kg APS), 800 mg/kg APS group (basal diet + 800 mg/kg APS), and 1200 mg/kg APS group (basal diet + 1200 mg/kg APS). The results indicated that adding 800 mg/kg APS to the diet significantly increased ADG (p < 0.001) and reduced F/G (p = 0.008). With increasing APS supplementation levels, slaughter weight (p = 0.035), eviscerated weight (p = 0.020), semi-eviscerated weight (p = 0.015), and semi-eviscerated yield percentage (p = 0.035) were all significantly increased. Additionally, dripping loss in muscle was significantly reduced in the 800 mg/kg APS group (p = 0.006). In addition, the villus height of the small intestine and the expression of tight junctions were significantly increased by 800 mg/kg APS supplementation, which reduced intestinal permeability and lowered levels of intestinal inflammatory mediators by inhibiting the PPARγ/NF-κB pathway. Additionally, a diet with APS significantly increased the abundance of Flavonifractor, a butyrate-producing bacterium in the cecum. Cell assays further demonstrated that butyrate could inhibit the release of inflammatory cytokines from RAW264.7 via the PPARγ/NF-κB pathway. In conclusion, APS improved growth performance by reshaping the gut microbiota and increasing the level of butyrate in the cecum, further inhibiting intestinal inflammation through the PPARγ/NF-κB signaling pathway.