ENHANCING THE EFFICIENCY OF OIL SEED BY-PRODUCTS BASED PRACTICAL DIETS FOR Labeo rohita FINGERLINGS

Abstract

The present study with Labeo rohita fingerlings was designed to investigate the effect of citric acid (CA), phytase (PHY) and organically chelated trace elements (TEs) supplementations in oil seed by-products based diets. The investigation was conducted in three feeding trials (90 days each) using soybean meal (SBM), sunflower meal (SFM) and canola meal (CM) as the main plant protein ingredient in trial 1, 2 and 3, respectively. The experimental layout (2×2×3) was same for all the three trials and was as follows; CA (0 and 3%), PHY (0 and 1000 FTU/kg) and TEs {(inorganic (0.1%) and organic (0.1% and 0.05%)}. Fish were fed in triplicates to apparent satiation twice a day, 6 days a week. Generally, all the three experimental diets showed similar responses against the supplementation of CA, PHY and organically chelated TEs. Addition of CA in these different plant meal based diets decreased the dietary and intestinal digesta pH. In vitro phytate hydrolysis was intensified with the addition of CA and PHY in these diets. In all three feeding trials, supplementing the diet with CA, PHY and organic TEs significantly (p<0.05) improved the growth performance of fingerlings compared to fish fed TEs from inorganic salts. Digestibility of dry matter (DM), crude protein (CP), ether extract (EE), ash and gross energy (GE) were significantly (p<0.05) affected by all of the three supplements. Similar observations were also made in case of mineral absorption. Higher deposition of Cu, Mn, Fe and Zn in bones and whole body was recorded by feeding organic TEs. Similarly, Deposition of most of the major mineral was also significantly influenced by the supplementation of organically chelated TEs, CA and PHY. Inclusion of CA, PHY and organic TEs in the diets showed significant increase in the retention of N and P in fingerlings fed different plant meal based diets. The addition of CA and PHY in the diet showed improved activities of amylase, protease and lipase in the intestine of fingerlings. Moreover, synergistically positive second and higher order interactions were observed for most of the studied parameters. In conclusion, supplementation of CA, PHY and organically chelated TEs alone as well as in combination, in oil seed by-product based diets, improved the nutrient utilization in fingerlings leading to improved growth performance.