Earthworm meal (Perionyx excavatus) as an alternative protein source to fish meal in feed for juvenile butter catfish (Ompok pabda)

Abstract

An experiment was carried out to determine the effect of replacing dietary fish meal protein with earthworm meal protein on growth performance, whole-body composition, and hematology of butter catfish (Ompok pabda). This experiment was conducted in 15 glass aquaria (200 L) with five treatments, each having three replications. Each of the aquaria was stocked with 40 fishes (average weight 0.62 g). The fish were fed with iso-nitrogenous diets having 35% protein (21% protein from fish meal and/or earthworm meal) twice a day up to satiation with the experimental diets, where fish meal protein was replaced by earthworm meal protein at 0% (control), 25%, 50%, 75%, and 100% in the treatments E0, E25, E50, E75, and E100, respectively. At the end of the 8-week rearing period, the best growth performances including weight gain (5.23 ± 0.14 g), percent weight gain (844.15 ± 6.38%), and specific growth rate (4.00 ± 0.11% day−1), and best feed utilization parameters, viz., feed conversion ratio (1.57 ± 0.03) and protein efficiency ratio (2.87±0.04), were found in treatment E75, where 75% of fish meal protein in the diet was replaced with earthworm meal protein. The hematological parameters showed no abnormality due to supplementation of earthworm meal in the diets. At the end of the experiment, whole-body carcass composition, viz., protein, lipid, and ash contents (15.93 ± 0.19%, 7.22 ± 0.60% and 2.14 ± 0.10%, respectively), of O. pabda was higher in treatment E75 compared to control (14.8 2± 0.34, 6.16 ± 0.27, 1.89 ± 0.10, respectively). The results imply that earthworm meal can be used as a protein-rich source to replace fish meal, the major protein source, in the diet of O. pabda up to 75% level without compromising growth, immunity, and body composition.