Effects of earthworm (Perionyx excavates) inclusion to the growth, feed utilization and lipid composition of common carp (Cyprinus carpio)

This experiment was conducted to evaluate the effects of earthworm (Perionyx excavates) inclusion in the diet of common carp (Cyprinus carpio) on the growth, feed utilization and fatty acid composition. Triplicates of four diets were used: control diet, EW30, EW70, EW100, in which 0, 30, 70 and 100% of fishmeal protein was replaced by earthworm protein, respectively. The experiment was carried out for 8 weeks in a recirculation system that consisted of 12 aquaria (40 L each and 5 fish per aquaria). Fish was fed five times daily with amount of five times higher than the maintenance requirement. Growth of fish was monitored weekly. Fatty acid composition of earthworm, feed and fish carcass were analyzed by gas chromatography to compare with standard peak areas. Results showed that the growth of fish fed on earthworm inclusion was significantly higher than that of the fish administered control feed. Within the earthworm inclusion diets, the EW70 group showed a better growth rate, significantly higher than EW30 and EW100. Results of fatty acid composition showed that the earthworm diet was limited in some poly unsaturated fatty acids (PUFA), such as C20(n-5), C22(n-4) and C24(n-6) fatty acids, which might have negatively affected the lipid utilization, leading to the lower growth rate in EW100. Nevertheless, PUFA concentrations of fish fed on earth worm inclusion diets were significantly higher than that of control.