Modeling the substitution of fishmeal by maggot-meal in Tilapia feeds - case of a commercial production farm in West Africa

Abstract

Intensive tilapia production (Oreochromis niloticus) is an emerging industry in West Africa. Access and availability of economically viable formulated commercial fish feeds are major constraints. The availability and cost of animal source ingredients such as fishmeal (FM), typically used in limited amounts to ensure balanced diets and high performance, is a global issue. Research has been conducted to identify and utilize locally produced, cost-efficient feedstuffs to partially or completely replace FM with a focus on plant and animal by-products. Interest in insect-derived meals, particularly fly larvae (Musca domestica, Hermetia illucens, etc.) as potential replacements for FM in aquaculture diets has increased. Commercial quantities of insect larvae, maggot meal, (MM) can be produced under tropical conditions due to their high rates of reproduction, growth, and their ability to grow on a large variety of organic substrates. Given the nutritional value and profile (comparability of amino acids, EFA, and micronutrients) of MM, this study evaluates strategies for: substitution of FM by MM, different methods of production and preparation of MM as a feedstuff, and availability of different substrates on which to produce fly larvae. A review of secondary data suggests that the nutritional value of MM is highly dependent on conditions of production (substrate, phenological stage of the maggots harvested) and processing (sun or oven dried, whole, chopped, defatted, etc.). A key question is how MM use can be optimized. This is modeled on a large-scale cage-inlake operation tilapia farm integrated with hatchery and juvenile production. The study is based on secondary data from hatchery, nursery, and grow-out tilapia operations at various locations to estimate annual MM requirements for food fish production of 6,000 metric tons (MT), juvenile production of 20 million fingerlings (10g), and a hatchery maintaining 10,000 broodfish. To substitute 30% of FM, in diets of each of these systems, the required annual MM production would be: 1.4 MTdry matter, (DM) for the broodstock; 60.8 MT (DM) for the juveniles; and 175.5 MT (DM) for the grow-out fish. Broodstock and juveniles have very high feed quality requirements, but the amounts required are relatively lower than for food/grow-out fish. A strategy for MM substitution may be optimized depending on the capacity to produce MM, fish feeding response, and performance results. Experiments on fly larvae production, capacity, and feeding trials with MM substituted feeds to validate this preliminary model, will be conducted in 2014 and 2015 in Ghana and UK.