Growth performance and chemical composition of tenebrio molitor larvae grown on substrates with different starch to fibre ratios

Abstract

Production of insects as animal protein source has increased recently but the information on nutrient requirements for optimal growth is still scarce. The effects of carbohydrate composition of the substrate on growth performance and chemical composition of Tenebrio molitor larvae were evaluated. Three substrates based on different proportions of wheat grain, wheat bran and soybean meal were formulated to contain three starch to neutral detergent fibre (NDF) ratios: low (1.0; LSF), medium (1.2; MSF) and high (1.4; HSF), at a common N level. Each treatment was replicated five times in trays containing 23 g of substrate and 40 larvae (2.95 mg average weight) each. Weight of the larvae and the substrate remaining per tray were weekly monitored from 21 to 49 days of experiment and larvae within the same experimental treatment were pooled at the end of the trial for chemical analysis. No treatment differences were observed for larval growth or mortality (p > 0.05). The starch to NDF ratio in the substrate did not affect larval composition in terms of dry matter, nitrogen or ether extact contents or the amino acid composition of the protein fraction. Within the range of ingredient composition considered, the starch to NDF ratio in the substrate has a minor influence on growth performance and chemical composition of T. molitor larvae.

Keywords

• starch
• fibre
• larval growth
• larval composition
• tenebrio molitor