High percentage of dietary soybean meal inhibited growth, impaired intestine healthy and induced inflammation by TLR-MAPK/NF-κB signaling pathway in large yellow croaker (Larimichthys crocea)

Soybean meal (SBM) is a high-quality protein source and widely used in aquafeeds. However, high percentage of dietary SBM would make negative influences on fish. Here, we evaluated the effects of dietary high level of SBM on growth, intestine healthy and intestinal inflammation in large yellow croaker. Two isonitrogenous (450 g kg−1) and isolipidic (100 g kg−1) diets were prepared, in which SBM was added at 0 or 45 %. An 8-week feeding trail was conducted by feeding fish (initial weight 18.2 ± 0.8 g) with these two diets. After feeding trail, SBM0 group had significantly enhanced growth performance, antioxidant capacity and digestive enzyme activities compared with SBM45 group (P < 0.05). Dietary SBM45 caused intestine injury symptoms and decreased intestine villus length of fish. In addition, dietary SBM45 induced intestinal inflammation of large yellow croaker, manifested as significant upregulation of pro-inflammatory cytokines and downregulation of anti- inflammatory cytokines (P < 0.05). The increased inflammatory response of SBM45 group may be due to activation of TLR-MAPK/NF-κB signaling pathway, as the mRNA expression levels of TLRs and protein levels of c-Rel, P65 and ERK were significantly increased in SBM45 group (P < 0.05). All these results indicated that high percentage of dietary soybean meal could inhibit growth, impair intestine healthy and induce intestinal inflammation possibly by TLR-MAPK/NF-κB signaling pathway in large yellow croaker