Improvement of Nutritive Value of Sesame Oil Cake in Formulated Diets for Rohu, Labeo rohita (Hamilton) After Bio-Processing Through Solid State Fermentation by a Phytase-Producing Fish Gut Bacterium

Sesame oil cake (SSC) was bio-processed through solid state fermentation (SSF) under optimized conditions by a phytase-producing fish gut bacterium, Bacillus subtilis subsp. Subtilis (JX292128). SSF significantly reduced anti-nutritional factors (e.g., phytic acid, tannins, trypsin inhibitor) and crude fibre, while it enhanced free amino acids, fatty acids and different minerals. Phytase production (39.72±1.06 U/g) during SSF was also recorded. Along with a fish meal based reference diet (RD), 8 isonitrogenous (36% crude protein) and isocaloric (4.60 kcal g^-1) experimental diets incorporating raw (R1-R4) and SSF processed (F1-F4) SSC (20%, 30%, 40% and 50%, w/w) were fed to rohu, Labeo rohita fingerlings (mean weight 3.28 ± 0.15 g) in triplicate treatments for 70 days. In general, growth and feed utilization efficiencies in fish fed diets containing SSF-processed SSC were superior to the groups fed diets containing raw SSC. The diet F3 (40% fermented SSC) showed significantly (P<0.05) better result in terms of weight gain, feed conversion ratio, protein efficiency ratio, apparent net protein utilization, activities of digestive enzymes, carcass composition and apparent digestibility of protein, lipid and phosphorus. Faecal phosphorus discharge reduced significantly (P<0.05) in fish fed fermented diets. Results indicated that incorporation of SSF-processed SSC might be practiced as a function to replace fish meal in the diets of L. rohita fingerlings.