Nutritional value of different insect larvae meals as protein sources for European sea bass (Dicentrarchus labrax) juveniles

Apparent digestibility coefficients (ADCs) of five commercially available insect larvae meals, H. illucens (HI and HId), T. molitor (TM and TMd) and a locust meal (LM), obtained from different producers, were assessed in European sea bass (Dicentrarchus labrax) juveniles. Each experimental diet was obtained by replacing 20% of a commercial-based diet used as reference (DREF), with 1% of chromic oxide added, by a test ingredient. Each diet was fed to quadruplicate groups of fish (initial weight: 33 ± 1 g) and, after an acclimatization period, daily collection of faeces was performed during 12 days. Dry matter ADC was highest in TM (85%) and lowest in LM (40%). Protein ADC was high in TMd (93%); intermediate in HId and TM (87 and 89%, respectively); and moderate in LM and HI (74 and 76%, respectively). Overall, the ingredient with highest digestible total essential amino acids (EAAs) content was TMd, followed by TM which was higher than HId; HI had a moderate amount of digestible EAAs, and LM had the lowest values. Fat ADC was highest for HId, TMd and TM (93%–95%). Energy and phosphorus ADC were highest in TMd (84% and 91%, respectively) and lowest in LM (53% and 27%, respectively). In conclusion, the high protein level, high protein digestibility and high amount of digestible EAAs of TM and TMd (> 89%) suggests that Tenebrio molitor larvae meals are the most promising protein sources tested for European sea bass, with potential to replace fishmeal without impairing nutrient digestibility.