Nutritional evaluation of a short-horned grasshopper\u201a Oxya hyla hyla (Serville) meal as a substitute of fishmeal in the compound diets of rohu, Labeo rohita (Hamilton)

Abstract

BackgroundAqua feed demand is rising with the growth of intensive aquaculture. Fishmeal is the major conventional protein source of fish feed but its production cannot be increased due to resource limitation. Thus, suitable fishmeal (FM) substitute is a need to sustain the growth of aquaculture. Use of edible insects in animal and fish feed is gaining interest. Grasshoppers are edible insect and contain considerably high percentage of crude proteins and other nutrients. In the present study, the nutritional efficiency of Oxya hyla hyla meal as replacer of FM was evaluated by feeding Labeo rohita fingerlings with seven iso-nitrogenous compounded diets (33% crude protein) where FM was substituted by Oxya meal (OM) at 0%, 17%, 33%, 50%, 67%, 83% and 100% levels in diet 1 (D1) to diet 7 (D7) respectively. Feeding trail was continued for 100 days.ResultsFeeding experiments showed that OM-incorporated diets were acceptable to the fish and feeding on the diets they grew significantly after 100 days feeding trial in wet weight and length. Results revealed that up to 50% replacement of FM (up to diet 4) did not affect the growth performances, condition factor of fish, apparent protein digestibility, nitrogen metabolism, food conversion ratio (FCR) and protein efficiency ratio (PER) with respect to reference diet (D1, without OM). FCR and PER were found inferior in the diets D5, D6 and D7 where more than 50% FM was replaced. Moreover, diets regardless of FM replacement level showed no negative impact on hepato-somatic index, digesto-somatic index, relative length of gut, retention of protein, lipid and ash and on carcass compositions of the fish.ConclusionThe results revealed that the grasshopper species, O. hyla hyla, might be a new protein-rich ingredient for aqua feed formulation and up to 50% replacement of FM by OM did not affect the growth performances, feed utilisation parameters and flesh quality of the fish L. rohita fingerlings. Therefore, this study suggested that OM meal could be incorporated at least as partial substitute of FM in the compounded carp diet.