Physical properties of extruded fish feed containing silkworm (Bombyx mori) pupae meal

Abstract

The silkworm pupae (Bombyx mori) may be an interesting resource for aquaculture feed, due to its high nutritional value. The present work evaluates the physical properties of five extruded diets for gilthead seabream (Sparus aurata) containing 0, 2.5, 5, 10 or 15% of non-defatted silkworm pupae meal. The physical properties studied included: expansion ratio, density, hardness, durability, water absorption index, water solubility index, floatability, sinking velocity and fat leakage. Feed formulated with insect meal showed an increase in expansion ratio, hardness and durability, while water absorption index and sinking velocity decreased. The pellets from these diets showed no increased nutrient leaching or fat leakage. Thus, it is possible to include up to 15% of silkworm pupae meal in extruded fish feed without impairing its physical quality.