To meet the projected substantial growth in the global demand for meat, we are challenged to develop additional protein-rich feed ingredients while minimizing the use of natural resources. The larvae of the black soldier fly (BSF) have the capacity to convert low-value organic resources into a high quality protein source for pigs, chickens and fish and as such may increase both the productivity and the efficiency of the food chain. The aim of this study was to assess the environmental opportunities of BSF larvae reared on different sources using up to date literature data on the efficiency of BSF larvae in converting such resources into biomass. The current EU legislative framework was used to classify the various resources for rearing insects. Data of forty articles published until 1 September 2017 were used, reporting on in total 78 (mixtures of) resources used for growing BSF larvae. Data on the resource conversion efficiency on dry matter (DM) and N basis was presented in 11 and 5 studies, evaluating 21 and 13 resources, respectively. Resources studied included food and feed materials (A, n=8 resources), foods not intended (anymore) for human consumption (B1, n=4), and residual streams such as food waste (D, n=2), and animal manure (E, n=7).Conversion efficiency varied from 1.3 to 32.8% for DM and from 7.4 to 74.8% for N. Using life cycle assessment, our environmental results showed that resources within the legal groups (i.e. A and B1) that are, at the moment, not allowed in EU as animal feed have in general a lower impact in terms of global warming potential, energy use, and land use. On a per kg protein basis, BSF larvae reared on a resource that contains food (e.g. sorghum) and feed (e.g. dried distillers grains with solubles) products generally have higher environmental impacts than conventional feed protein sources (fishmeal and soybean meal). Using insects as feed, therefore, has potential to lower the environmental impact of food production but a careful examination of the resource is needed in terms of environmental impact, safety and economics.
Edible insects are advocated as sustainable and healthy food and feed. However, commercially produced insects are often low in n-3 fatty acids and have suboptimal n-6/n-3 ratios. A certain amount and proportion of these FAs is required to optimize human health. Flaxseed oil consists primarily (57%) out of alpha-linolenic acid. An experiment was conducted to quantify the effect of flaxseed oil provision on fatty acid composition and to determine the quantity needed to attain a beneficial n-6/n-3 ratio. Three species were used in the experiment: house crickets (Acheta domesticus [L.]), lesser mealworms (Alphitobius diaperinus [Pfanzer]) and black soldier flies (Hermetia illucens [L.]). These were provided with either a control diet or a diet enriched with 1%, 2%, or 4% flaxseed oil during their larval/nymphal stage. Fatty acid profiles of diets and insects were determined via GC-MS. The three species had distinct fatty acid profiles on all four diets, but responded similarly to flaxseed oil addition. For each percent added to the diet, the alpha-linolenic acid content of the insects increased by 2.3%-2.7%. Four percent addition increased the n-3 fatty acid content 10-20 fold in the three species and thereby strongly decreased n-6/n-3 ratios from 18-36 to 0.8-2.4. A ratio below 5 is considered optimal for human health and was achieved by 2% flaxseed oil inclusion for house crickets and lesser mealworms, and at 1% inclusion for black soldier flies. Adding a source of n-3 fatty acids to insect diets can thus improve the nutritional quality of insects.
Dietary deficiencies in Fe and Zn are globally widespread, causing serious health problems such as anaemia, poor pregnancy outcomes, increased risk of morbidity and mortality, stunted growth and impaired physical and cognitive development. Edible insects, of which a diversity of over 2000 species is available, are dietary components for about 2 billion individuals and are a valuable source of animal protein.In the present paper, we review the available information on Fe and Zn in edible insects and their potential as a source of these micronutrients for the rapidly growing human population. The levels of Fe and Zn present in eleven edible insect species that are mass-reared and six species that are collected from nature are similar to or higher than in other animal-based food sources. High protein levels in edible insect species are associated with high Fe and Zn levels. Fe and Zn levels are significantly positively correlated. Biochemically, Fe and Zn in insects occur predominantly in non-haem forms, bound to the proteins ferritin, transferrin and other transport and storage proteins. Knowledge gaps exist for bioavailability in the human alimentary tract, the effect of anti-nutritional factors in other dietary components such as grains on Fe and Zn absorption and the effect of food preparation methods. We conclude that edible insects present unique opportunities for improving the micronutrient status of both resource-poor and Western populations.
The demand for house crickets as a source of food or feed is increasing. Meeting this demand will require efficient production systems. House crickets are often fed a combination of dry feed and fresh plant material. Supplying fresh plant material could improve growth and development, but also increases labour and costs. Two experiments were conducted to verify that provision of fresh plant materials has a beneficial effect on house cricket performance. In the first experiment, house crickets were provided with an ad libitum supply of chicken feed, a water dispenser, and with carrots at different frequencies: (1) daily; (2) three times a week; (3) first week daily then three times a week; (4) two weeks daily then three times a week; and (5) no carrots. When the first cricket in a container reached adulthood, all crickets in that container were harvested. Survival, development time and body weight were determined. In a second experiment feed conversion efficiency of house crickets, either provided with carrots daily or not at all, was compared. No effects of carrot provision on survival, development time, body weight or feed conversion efficiency were found. The outcomes of these parameters were similar to other studies in which crickets were provided with chicken feed. The results indicate that supplying carrots in addition to a suitable dry feed and water does not improve house cricket survival, development time, body weight and feed conversion efficiency.
Background Edible insects are a novel source of animal protein. Moreover, edible insects contain iron concentrations similar to meat, potentially making them a valuable iron source for human consumers. Yet, it is unknown to what extent iron from insects is absorbed in humans. Objectives In this exploratory study, we assessed fractional iron absorption from house crickets (Acheta domesticus) consumed with refined (low-phytate, non-inhibiting) or non-refined (high-phytate, inhibiting) meals. Methods Intrinsically [57Fe]-labeled and control crickets were reared. Six iron-balanced experimental meals were randomly administered cross-over to 20 iron-depleted females (serum ferritin <25 µg/L; 18–30 years), in two time-blocks of three consecutive days, two weeks apart. Three meals consisted of refined maize flour porridge with either [57Fe]-labeled crickets, [58Fe]SO4 (reference meal), or unlabeled crickets plus [54Fe]SO4. The other three meals consisted of non-refined maize flour porridge with the same additions. Blood samples were drawn to assess the 14-day isotope enrichment in erythrocytes, and meal-specific fractional iron absorption was calculated. In vitro digestion was used to explore possible explanations for unexpected findings. Results Mean fractional iron absorption from 57Fe-labeled house crickets with refined maize porridge (3.06%) and from refined maize porridge with unlabeled crickets (4.92%) was lower than from the reference meal (14.2%), with respective mean differences of -11.1% (95% CI -12.6, -9.68%) and -9.29% (-10.8, -7.77%). Iron absorption from all meals based on unrefined maize porridge was low (<3%), and did not differ for the two meals with crickets compared to the reference meal. In vitro digestion showed that chitin, chitosan, and calcium limited iron bio-accessibility to a large extent. Conclusions Iron absorption from house crickets and fortified maize porridge with crickets is low, which may be explained by the presence of chitin and other inhibitors in the cricket biomass. This study was registered in the Netherlands Trial Register, https://www.trialregister.nl/trial/6821. This study was registered in the Netherlands Trial Register, Trial ID: NL6821, source ID: NL59400.081.16, https://www.trialregister.nl/trial/6821.
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