Nutritive Characterization of Delimed Bovine Tannery Fleshings for Their Possible Use as a Proteinaceous Aqua Feed Ingredient

Abstract

Increased demand for animal protein additives in aquaculture has initiated the search of an alternative cheap protein source for aquatic animals, which can compensate the amino acids level of fishmeal (FM) and act as a valuable feedstuff. Abundantly available pre-tanned proteinaceous solid wastes from leather industries [bovine tannery fleshings (BTFs)] are valuable sources of dietary proteins and could be exploited as a FM replacer. Wet limed fleshings from bovine hides (pH 12) were delimed with 1.5% formic acid [1:10 (w/v)] solution containing 0.1% v/v hydrogen peroxide (H2O2). Delimed bovine tannery fleshings (DBTFs) were characterized and fermented using Lactobacillus plantarum. Five isonitrogenous diets were formulated for Labeo rohita; where in fermented tannery fleshings flour (FTF) replaced FM by 25, 50, 75 and 100%. Ideal diet was subjected to multimycotoxins analysis. Eleven saturated and one monounsaturated fatty acids were detected through gas chromatography and mass spectrometry (GC-MS) in DBTFs. High performance thin layer chromatography (HPTLC) results confirmed the presence of ten indispensable and six dispensable amino acids. Superior growth performance, nutritional indices and body carcass composition (P < 0.05) were observed in fish group fed with diet formulated by replacing FM with 75% FTF (diet FTF3), followed by 50 and 25% replacement. Multimycotoxins analysis in FTF3 revealed the absence of potent feed toxins in the diet. Recycling of BTFs by recovery of its biomolecules will be a beneficial remedy for long-term environmental threat associated with its disposal, supporting aqua feed processing concerns to reduce production costs.