| Abstract: | Five diets were prepared to include date palm seed meal (DSM) fermented with Aspergillus oryzae (ASP) at 0, 50, 100, 150 and 200 g/kg diet and fed for Nile tilapia (26.93 ± 0.01 g) for 8 weeks. Fermented DSM significantly affected the final weight, weight gain and specific growth rate in a dose‐dependent manner (p = .001) with insignificant differences in feed conversion ratio (p > .05). Dietary fermented DSM significantly increased the lipase, amylase and protease activities (p = .008, p = .001 and p = .01, respectively) and the Hb, RBCs and WBCs (p = .001, p = .005, and p = .009, respectively). The intestinal villus length and number of goblet cells were significantly affected by fermented DSM inclusion (p < .05). Additionally, the total protein, albumin and globulin significantly affected by the inclusion of fermented DSM in a dose‐dependent manner (p = .04, p = .045, and p = .03, respectively). Furthermore, dietary fermented DSM significantly altered the phagocytic index, phagocytic activity and lysozyme activity (p = .001, p = .045 and p = .04, respectively). Based on the polynomial regression analysis, the inclusion of fermented DSM at 103.3–164.8 g/kg diet can be used effectively in tilapia diets for improving the growth, digestion activity and immune response. |
