Nutrient Composition of some Tropical Legumes Capable of Substituting Fish Meal in Fish Diets

Abstract

Sword beans (Canavalia gladiata); Jackbean (Canavalia enciformis (L)); Mucuna bean (Mucuna pruriens); Mucuna cochiunensis; Bambara (Voandzeia subterranea) and Limabean (Phaseolus lunatus) are the tropical legumes considered in this paper. They have been used in the feed of ruminants but very scarcely considered in fish feed. Information about their nutrient composition are also scarce. Results from this study show that the protein contents of the test seeds ranged from 19.94% dry matter (DM), (Bambara) to 36.95% DM (Mucuna cochiunensis). Considering the high protein level required by fish for maximum growth and the presence of some ANFs, the seeds may not be able to be used in isolation without supplementing them with other food stuffs having higher protein value. The relatively high content of Nitrogen Free Extract (+ fibre) seem to suggest that the test seeds can be used in a semi-intensive setting to supply carbohydrate in fish diets. The seeds contain considerable amount of linoleic acid (18:2 n-6). The highest occurring in Lima beans. Sword beans and Jack beans are rich in oleic acid (18:1n-9). Palmatic acid (16:0) is high, while stearic acid (18:0) and myristic acid (14:0) are low. The amino acid compositions of the test seeds are not very adequate. Sword beans had a better amino acid profile though it seems deficient in some of the amino acids. The amino acid contents of Jack bean, Mucuna bean, Bambara and Lima bean look inadequate to provide a possible alternative to fish meal on individual basis. If to be used in fish feed formulation, combinating them with other protein sources, possessing higher contents of the limiting amino acids is strongly suggested. The potentials of these seeds in fish feed formulation seem high.