Effects of dietary inclusion of yellow mealworm (Tenebrio molitor) meal on growth performance and proteolytic enzymes activity of koi carp (Cyprinus rubrofuscus) juvenile

The present study was conducted to evaluate the effect of fish meal replacement with yellow meal worm (Tenebrio molitor) (TM) on growth performance and proteolytic enzymes activity of trypsin and alkaline protease in koi (Cyprinus rubrofuscus) juvenile (weight: 0.95 ± 0.15 g) for 8 weeks. Five experimental diets were prepared with replacement levels of 0 (control), with 25% (D1), 50% (D2), 75% (D3) and 100% (D4) of fish meal with TM as isonitrogenous and isoenergetic in triplicate. Parameters of body weight gain, specific growth rate and condition factor in control, D1 and D2 diets were not shown a significant difference, while these indices had a decreased amount in D3 and D4 diets significantly (p < 0.05). The highest amount of feed conversion ratio was indicated in control and D1 diets with a significant difference than those from other treatments (p < 0.05). The survival rate was 100 % in the diets. The lipid efficiency ratio and the protein efficiency ratio in diets control, D1 and D2 were significantly the higher than other treatments (p < 0.05). The highest activity of trypsin and alkaline protease enzymes from intestine was observed in control, D1 and D2 groups which showed a significant difference compared to D3 and D4 groups (p < 0.05). The findings of growth performance and protease enzymes activity were revealed that the diets containing up to 50% TM could be appropriate for koi growth.