Insect meal is an alternative source of protein with a great potential to substitute fishmeal in aquafeeds, but depending on the utilized insect species, the protein composition of the insect meal varies.

Portuguese researchers, together with Sorgal, tested five commercially available insect larvae meals, Hermetia illucens (HI and HId), Tenebrio molitor (TM and TMd) and a locust meal (LM) obtained from different producers, in European sea bass (Dicentrarchus labrax) juveniles assessing its apparent digestibility coefficients (ADCs). 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.

Dry matter ADC was highest in TM and lowest in LM. Protein ADC was high in TMd and moderate in LM and HI. Researchers found that the ingredient with highest digestible total essential amino acids 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. Energy and phosphorus ADC were highest in TMd and lowest in LM.

Researchers conclude that due to the high protein level, high protein digestibility and high amount of digestible EAAs of TM and TMd, Tenebrio molitor larvae meals are the most promising protein sources tested for European sea bass, with potential to replace fishmeal without impairing nutrient digestibility.

Check the study here.