Substitution of Earthworm Meal with a Portion of Fishmeal in the Diet of Nile Tilapia (Oreochromis niloticus)
Fingerlings of Nile tilapia (Oreochromis niloticus) of mean weight 2.15±0.01g were fed on earthworm meal as a substitute for a portion of fishmeal for 10 weeks to determine the effect on growth and nutrient utilization. The fish were fed isonitrogenous Diets (40% crude protein) containing 10%, 15%, 25%, 30%, 40%, and 0% earthworm meal. Greatest growth (50%) was observed in Diet 6 (40% fishmeal). This was followed by Diet 2 (15% earthworm) with weight gain of 43.73%. Best condition factor, food conversion and protein efficiency were recorded in Diet 6 followed closely by Diet 2. Analysis of body composition revealed similar results, with Diet 2 following closely Diet 6 in protein and fat contents. Diet 5 (40% earthworm meal) recorded the lowest values of all these parameters. From these results it could be concluded that Diet 2 can be a good substitute for a portion of fishmeal in the diet of Oreochromis niloticus but the cost-benefit analysis showed that the cost of producing earthworm meal diet is incomparably higher than that of producing equivalent diet using fishmeal as a protein source. Hence, replacing fishmeal with earthworm meal in tilapia diet may not be beneficial to farmers.
Key Words: Substitution, Earthworm meal, Diet, Fishmeal, Nile tilapia