Skin Mucus Protein Profile, Immune Parameters, Immune-Related Gene Expression, and Growth Performance of Rainbow Trout (Oncorhynchus mykiss) Fed White Button Mushroom (Agaricus bisporus) Powder

An 8-week feeding trial was performed to assess the effects of dietary white button mushroom (Agaricus bisporus) powder (WBMP) on the mucosal immunity and growth of rainbow trout (Oncorhynchus mykiss). Trout (n = 192; weight 13.76 ± 1.17 g) were stocked in 12 cages (65 × 65 × 65 cm) placed in 4 raceways with a flow-through water system. Trout were fed a basal diet (control group) or a basal diet supplemented with 0.5%, 1%, or 2% WBMP for 8 weeks. Evaluation of total protein levels and lysozyme activity in skin mucus revealed noticeable increases in trout fed 1% or 2% WBMP (P < 0.05), but no significant difference was observed with 0.5% WBMP administration (P > 0.05). The results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed alterations in the protein profile of skin mucus following dietary administration of WBMP. Molecular studies showed a noticeable increase (P < 0.05) in tumor necrosis factor-α messenger RNA in the intestine of WBMP-fed trout, regardless of the inclusion level. Also, fish receiving the 1% or 2% WBMP treatments had a remarkable increase in interleukin (IL)-1β expression compared with the control group (P < 0.05). In a similar way, intestinal IL-8 expression was upregulated with the 1% and 2% WBMP treatments (P < 0.05). However, no significant difference was found between the control group and the 0.5% WBMP treatment group in the case of IL-8 gene expression (P > 0.05). Furthermore, after 8 weeks of WBMP feeding, no improvement was seen in the growth parameters of trout compared with those fish fed the nonsupplemented diet (P > 0.05). These results hint at the potential immunomodulatory effects of dietary WBMP.