Rearing house crickets on substrates enriched by flaxseed and rapeseed oils: the more the better?
Diet is one of the most important factors influencing the chemical composition of edible insects. In this study, soybean meal and soybean oil were partially replaced with rapeseed pomace, rapeseed oil, or flaxseed oil in the insect diet. House crickets were provided with enriched diets for their whole life, ten, or five days before harvest to assess the effect of the supplement over time. The replacement of soybean oil with either rapeseed or a combination of rapeseed and flaxseed oils resulted in decreased levels of saturated fatty acids and increased levels of linolenic acid and mono unsaturated fatty acids. The longer the supplementation period, the higher the mono unsaturated fatty acids and the lower the saturated fatty acid levels. The dietary enrichment also led to increases in α- and γ-tocopherols. While short-term supplementation with cricket feed did not lead to significant changes in the mineral profile, whole-life provision of enriched feed led to decreased levels of Fe, Cu, and Zn and increased Mg in the crickets. Whole-life diet supplementation also resulted in higher harvest yields.