Appraisal of fermented wheat bran by Saccharomyces cerevisiae on growth, feed utilization, blood indices, intestinal and liver histology of Nile tilapia, Oreochromis niloticus

This work is an additional attempt to increase the nutritive value of wheat bran and to provide a solution to the problem of high fiber contents in this by-product. Wheat bran (WB) was fermented by baker's yeast (Saccharomyces cerevisiae) to figure out its impact on crude fiber (CF), crude protein (CP), and amino acids profile as well as fed Nile tilapia (Oreochromis niloticus) to determine the effects on the feed utilization, growth, blood indices, and intestinal and liver histology. Yeast fermentation of wheat bran (YFWB) reduced fibers from 13.02% to 9.28%, raised WB CP to 22.35%, increased total amino acids, and reduced phytic acid from 4.31 mg g−1 to 0.08 mg g−1. By inclusion YFWB at different levels (0%, 15%, 20%, and 25%) in tilapia diets, four isonitrogenous practical diets were formed. During 70 days, each diet was fed to three replicates groups of fish weighing 6.36 ± 0.005 g at the start. Fish fed Diet 2 (20% YFWB) had the best final body weight (FBW), weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) using polynomial regression. Nonetheless, tilapia hemoglobin, hematocrit, MCV, MCH, MCHC, WBCs, monocytes, lymphocytes, and neutrophils increased linearly (P = 0.023; P = 0.02; P = 0.011; P = 0.023; P = 0.042; P = 0.025; P = 0.056; P = 0.025; P = 0.012, respectively) as the level of YFWB increased in the diet. The inclusion of YFWB in tilapia diets resulted in a linear reduction in the profile of lipids, which comprises triglycerides, LDL-C, HDL-C, Non-HDL, and VLDL-cholesterol, but had no influence effect. The dry matter, ash, lipid, and protein contents did not affect either linearly or quadratically (P > 0.05) by adding YFWB in diets. It is possible to infer that fermentation of wheat bran by baker's yeast (S. cerevisiae) increases protein content while decreasing fiber content; its inclusion up to 20% in tilapia diets enhances development, feed utilization, blood indices, and intestinal and liver architecture.