Animal Waste and Agro-by-Products: Valuable Resources for Producing Fish at Low Costs in Sub-Saharan Countries

Abstract

Animal and crop production throughout the world generate high amounts of wastes or by-products annually that may possess added value compounds with high functionality. These wastes and by-products may cause negative environmental impacts and significant expenses if not well managed and or controlled. Much of these wastes and by-products is valuable and cheaper source of potentially functional compounds such as proteins, lipids, starch, micronutrients, bioactive compounds, and dietary fibbers. In aquaculture, feed is expensive, and the existing body of literature has shown that animal manure and its extracts can be successfully incorporated into fishpond to increase fish production at a low cost. In addition, crop residues such as rice bran, maize bran, and seed cakes are commonly used as pond inputs in small-scale aquaculture. Animal waste and crop residues are added in a fishpond that filter-feeding fish can use directly as feed, and these may form a major proportion of the detritus in the pond. These resources also stimulate the growth of phytoplankton that are rich in protein and are the basis of the food web that can support the growth of a range of herbivorous and omnivorous fish. Therefore, technically, wastes are used as direct feed, a source of minerals for autotrophic production and a source of organic matter for heterotrophic production. In this context, animal manure and crop residues have been used to provide great opportunities to improve food security. The purpose of this review is to project the potential of animal waste and agro-by-products as a sustainable alternative as aquaculture inputs to reduce poverty, malnutrition, and hunger in developing countries.