The Potential of Solid Organic Wastes as Fish Feed Ingredients in Selected Areas of Southwest Ethiopian Towns

Abstract

Limited availability and high costs of high-quality, sustainable fish feed impede aquaculture development in Ethiopia. This study explores the potential of utilizing readily available solid organic wastes as alternative fish feed ingredients. The research focused on selected areas within southwest Ethiopia: Jimma, Bonga, and Buno Bedele towns. A questionnaire assessed the availability, accessibility, and annual quantity of solid waste generated by various entities. Proximate analysis evaluated the nutritional value of collected wastes, including cattle blood, tella atela, brewery waste (spent grain), cabbage leftovers, poultry manure, various vegetable peels (beetroot, potato, onion, head cabbage), rumen liquor, coffee and tea brewing residues, cow dung, and coffee husk. Selection criteria for potential fish feed ingredients prioritized availability (abundance of the material), accessibility (ease and cost of acquisition), and quantity (consistent, reliable supply to meet production needs). The study revealed that most surveyed solid organic wastes satisfied these criteria. The majorities were readily available, freely accessible, and generated in significant quantities (100 – 100,000 kg/year) throughout the year. Notably, most wastes were not commercially sold, making them readily affordable for entities that did sell them. Key stakeholders expressed positive sentiment regarding the utilization of these wastes as fish feed, but a knowledge gap was identified that requires further information dissemination. The nutrient composition analysis (per 1 gram of dry matter) identified cattle blood (78.33% crude protein) as a promising protein source. Additionally, tella atela (20.0% crude protein & 45.10%), brewery waste (spent grain) (26.51% crude protein & 52.8% carbohydrate), cabbage leftovers (25.82% crude protein & 40.34% carbohydrate), and poultry manure (23.5% crude protein & 38.8% carbohydrate) demonstrated potential as combined protein and energy sources. Beetroot peel (59.11% carbohydrate), potato peel (59.0% carbohydrate), head cabbage leftover (54.0% carbohydrate), rumen liquor (51.4% carbohydrate), tea brewing residue (51.12% carbohydrate), cow dung (36.80% carbohydrate), and onion peel (48.33% carbohydrate) were identified as potential sources of dietary energy for fish. This study successfully identified several promising solid organic wastes as substitutes for conventional fish feed ingredients. Furthermore, the research demonstrates the viability of these wastes as locally-sourced, sustainable sources of protein and energy for fish feed formulations.