Preliminary Evaluation of Jackbean (<i>Canavalia ensiformis</i> L.DC) Seed Meal as a Substitute for Fishmeal in diets for <i>Clarias gariepinus</i> (Burchell, 1822)

Abstract

Jackbean (Canavalia ensiformis) is an under-utilized legume with crude protein content and amino acid profile that make it a potential ingredient in the tropics as substitute for fish meal in fish diets. This study assesses the potentials of Jackbean seed meal (JBSM) for partial replacement of fish meal in diets of Clarias gariepinus. Fishmeal in control diet was replaced progressively (10%, 20% 40% and 60%) by raw JBSM, 30-and 60-minute boiled JBSM. Test fish in each tank were fed 3% of their biomass twice daily for 56 days. Fish fed control diet had the best performance (Specific growth rate 1.6; Feed conversion ratio 1.88: Protein efficiency ratio 1.74). Specific growth ratio and PER of fish groups fed test diets were inversely related to the dietary levels of JBSM. The same trend applied to protein and fat contents of the fish carcass. Feed conversion ratio however had the reverse trend. Fish fed diets with up to 20% fishmeal substituted by 60 minute boiled JBSM had protein content similar to those fed the control diets (P<0.05). Fish fed diets with fishmeal substituted by 10% raw JBSM and up to 20% JBSM boiled for 30 and 60 minutes had similar fat levels in the fish flesh as those fed the control diet (P<0.05). The poor performance observed in fish fed diets containing increasing levels of boiled JBSM suggest the presence of probably thermostable antinutritional factors in processed JBSM as well imbalance in the nutrient profile which may be corrected by supplementation. However, the study shows that 20% of fishmeal in the diet can be replaced with JBSM boiled for 60 minutes without any adverse effect on the growth performance.

Keywords: Canavalia ensiformis seed meal; Clarias gariepinus; fishmeal substitute

> International Journal of Agriculture and Rural Development Vol. 9 2007: pp. 7-11