Bioconversion of Terminalia arjuna bark powder into a herbal feed for Labeo rohita: Can it be a sustainability paradigm for Green Fish production?

Abstract

Surging demand of fish production for nutritional and livelihood security manifested with irrational use of synthetic growth enhancer and immunostimulants which are fostering the awful health concerned to human being and negatively affecting the beneficial micro-biota in aquatic ecosystem. The need of hour is to use environment friendly herbal therapy, as an alternate to those chemicals and compounds. The Terminalia arjuna is known for its excellent array of ethnomedicinal properties including antimicrobial, antioxidant and was reported to have positive effects on metabolomics of the animals. A 90-day experiment was conducted to ensure effective valorization of Terminalia arjuna bark powder (TABP) based feed in Labeo rohita. Four iso-nitrogenous {305.74 g crude protein (CP)/ kg diet} and iso-caloric {18.15 MJ gross energy (GE)/kg diet} experimental diets were formulated incorporating 0.0, 5.00, 10.00 and 15.0 g TABP /kg feed and designated as TABP0, TABP5, TABP10 and TABP15, respectively. 540 juveniles (average weight, 20.7 g, 45 fish per tank) were randomly stocked in 12 fibre reinforced plastic (FRP) tank (500 L water capacity). Fish were fed twice at 9.30 h and 5.00 h to satiation level. Results of this study revealed the highest growth rates {weight gain percentage (WGP) and specific growth rate (SGR)}, nutrient utilization {protein efficiency ratio (PER), apparent net protein utilization (ANPU), fat retention (FR) and energy retention (ER)} and survival percentage (SRP) in L. rohita at 10 g TABP/ kg feed. While feed conversion ratio (FCR) followed an inverse trend (P < 0.05) to growth rates. Growth rates, feed conversion, and nutrient utilization were similar in TABP0 and TABP15 group (P > 0.05). Viscerosomatic index (VSI) and craniosomatic index (CSI) were significantly affected (P < 0.05) while hepatosomatic index (HSI) was insignificant (P > 0.05). Whole body composition was influenced (P < 0.05) excluding ash content (P > 0.05). RNA content and RNA: DNA ratio were positively correlated to growth rates and nutrient retentions (P < 0.05). Thus, present study advocated that TABP at 12.3 g/kg could be utilized efficiently to produce healthy fish for human consumption thereby called Green Fish. Also, paved a prolific way to produce an effective TABP based medicated feed on large scale, having tried in field conditions individually and with commercial feed.