Evaluation of processed meat solubles as replacement for fish meal in diet for juvenile grouper Epinephelus coioides (Hamilton)

Abstract

Feeding experiments were conducted to determine the efficacy of low fish-meal-based diets for juvenile grouper Epinephelus coioides (Hamilton). A diet containing 44% protein was formulated using fish meal as the major protein source. Processed meat solubles, a rendered by-product of slaughterhouses, was tested as a replacement for fish meal at increasing percentages from 0 to 100% in isonitrogenous diets. Eight dietary treatments representing fish-meal replacements were arranged in a completely randomized design with four replicates per treatment. Twenty-five fish were reared in circular fibreglass tanks of capacity 250 L, maintained in a flow-through seawater system and fed at 5–6% of total biomass, provided daily at 08:00 and 16:00 for 60 days. Results indicate that processed meat solubles can replace 40% of fish-meal protein with no adverse effects on weight gain, survival and or feed conversion ratio of E. coioides juveniles. Higher inclusion levels resulted in a significant decline in growth performance and inefficient feed conversion ratios, which may partly result from the lack of essential nutrients such as essential amino acids in meat solubles. This study has shown that the use of processed meat solubles substantially lowers the level of fish meal required in juvenile grouper diet and can be an efficient means of turning byproducts from slaughterhouses into a useful feed resource.