Abstract Because of an increasing world population, with more demanding consumers, the demand for animal based protein is on the increase. To meet this increased demand, alternative sources of animal based protein are required. When compared to conventional production animals, insects are suggested to be an interesting protein source because they have a high reproductive capacity, high nutritional quality, and high feed conversion efficiency, they can use waste as feed and are suggested to be produced more sustainably. This thesis starts with a historical perspective on insects as food and feed, and explains why insects are expected to be more suitable production animals. In Chapter 2 the nutritional quality of insects is discussed based on a variety of insects that are commonly used as feed or food. Additionally, various environmental and dietary factors which are known to significantly affect insect chemical composition are reviewed. In Chapter 3 the direct production of greenhouse gases (GHG) and ammonia, as well as carbon dioxide emission and average daily weight gain of five insect species is quantified. Differences regarding the production of GHGs (expressed as CO2 equivalents) between insect species were mainly due to the production of methane. All species tested emitted lower amounts of GHG than cattle, had a higher growth rate than cattle or pigs, and emitted lower amounts of ammonia and either comparable or lower amounts of GHG than pigs. Results from Chapter 3 were used in a Life Cycle Assessment conducted in Chapter 4. For a mealworm production system total GHG production, energy use, and land use were quantified and compared to conventional sources of animal protein. This chapter shows that mealworms should be considered a more sustainable source of edible protein, and that a large part of their environmental impact is due to the feed they consume. In Chapter 5 four diets composed from industrial organic by-products were formulated such that they varied in protein and fat content. These diets were offered to four insect species and their feed conversion efficiency was determined. Diets used in large scale production systems were included and served as controls. Diet composition affected feed conversion efficiency in all species. It is concluded that the four investigated species are efficient production animals and can therefore be considered interesting for the production of feed or food. Furthermore, diet composition affected insect composition, indicating possibilities to tailor the composition of these insects to best meet consumers’ needs. In Chapter 6 the suitability of chicken, pig, and cow manure was compared as feed for larvae of the Black Soldier Fly, which in turn could be used as feed for conventional production animals. Newly hatched larvae were directly inoculated on moistened manure. Whereas survival was high on all three tested substrates, the development time was greatly prolonged compared to the control diet. On pig manure, more nitrogen was utilised than on chicken and cow manure, while P utilisation was highest on cow manure. A large proportion of manure nitrogen was lost in all treatments, indicating that the production system would require a way to prevent this in order to make it ecologically sound. Furthermore, to improve economic viability, shorter development times would be required. In Chapter 7 the suggestions why insects would make suitable production animals are evaluated based on both literature data, and data gathered in this thesis. Furthermore, prospects for insects as food or feed are put forward, with emphasis on the knowledge and legislation requirements for the further development of the insect production sector.</p
