Insect fat as feed: Potential to modify the fatty acid composition of animal-derived foods

Insect products are attracting both scientific and commercial interest because of their high quality as food and feed, with insect farming having a low environmental impact and the potential to mitigate food-feed-fuel competition. Research on edible insects has primarily focused on their role as alternative protein sources, but the use of insect fat as feed offers a tool to modulate the fatty acid (FA) profile of animal-derived foods. In this review, we conducted a systematic literature search on the composition of insect fats and their effects in animal feeding trials. We compiled two datasets of FA profiles: insects used as feed (n = 120) and associated animal-derived products (n = 378). Most studies were available in aquaculture and poultry, but despite fewer publications in pigs, rabbits, and ruminants, results also seem promising in these species. Based on our dataset, insects can be described as non-conventional feeds with conventional FA profiles that could easily replace plant oils in animal diets without significantly altering the ration. Nevertheless, a greater analytical effort is needed to improve insect FA descriptions. In general, a limited number of insect species have been used as feed, primarily Hermetia illucens and Tenebrio molitor, with opposite effects on the FA profile of animal products: the former consistently increases saturated FA content (12:0 and 14:0) in fish, meat, and eggs, while the latter usually improves the concentration of unsaturated FA (cis-9 18:1 and 18:2n-6). Responses to the use of other insect species are associated with their specific FA profiles. However, inconsistent effects of insect fats have often been described in the literature, largely due to the degree of unsaturation of the fat in control diets. As a general recommendation, when the aim is to improve the FA profile of animal products, insects should replace feeds with an equal or lower degree of unsaturation. Because few studies have evaluated the use of extracted insect oils as feed, a major effort is needed in the coming years to define recommended levels of inclusion and examine potential interactions with basal diet composition.