Insect-based diets high in lauric acid reduce liver lipids in freshwater Atlantic salmon

We evaluated the effect of a diet containing insect meal and insect oil on nutrient utilization, tissue fatty acid profile and lipid metabolism of freshwater Atlantic salmon (Salmo salar). Insect meal and insect oil from black soldier fly larvae (Hermetia illucens, L.; BSF), naturally high in lauric acid (12:0), were used to produce five experimental diets for an eight‐week feeding trial. 85% of the dietary protein was replaced by insect meal and/or all the vegetable oil was replaced by one of two types of insect oil. A typical industrial diet, with protein from fishmeal and soy protein concentrate (50:50) and lipids from fish oil and vegetable oil (33:66), was fed to a control group. The dietary BSF larvae did not modify feed intake or whole body lipid content. Despite the high content of saturated fatty acids in the insect‐based diets, the apparent digestibility coefficients of all fatty acids were high. There was a decrease in liver triacylglycerols of salmon fed the insect‐based diets compared to the fish fed the control diet. This is likely due to the rapid oxidation and low deposition of the medium‐chain fatty acid lauric acid.publishedVersio

Shotgun proteomics approaches for authentication, biological analyses, and allergen detection in feed and food-grade insect species

Untargeted proteomics can contribute to composition and authenticity analyses of highly processed mixed food and feed products. Here, we present the setup of an analytical flow tandem mass spectrometry method (AF-HPLC HR-MS) for analysis of insect meal from five different species. Data acquired were compared with previously published data employing spectra matching and standard bottom-up proteomics bioinformatics analyses. In addition, data were screened for insect species marker peptides and common allergens, respectively. The results obtained indicate that the performance of the newly established AF-HPLC HR-MS workflow is in line with previously published methods for insect species differentiation. Data obtained in the present study, also lead to the discovery of novel markers for the development of targeted MS analyses of insect species in food- and feed-mixes and highlighted that known allergen such as arginine kinase or tropomyosin were consistently detected across all five species tested.publishedVersio

Assessing amino acid solubility of black soldier fly larvae meal in Atlantic salmon (Salmo salar) in vivo and in vitro

In vitro and in vivo methods were used to evaluate amino acids solubility of black soldier fly (BSF) larvae meal and two experimental diets (reference and test diets) for Atlantic salmon. The current study used in vitro method such as pH stat to compare and standardise the salmon extracted enzyme (SE), and commercial enzyme (CE) based on their hydrolytic capacity on a purified protein substrate. Further, an in vitro amino acid solubility of feed ingredients and diets were measured using the standardised enzyme volume from SE and CE. Results showed that SE and CE exhibit similar protein hydrolytic capacity upon standardisation on purified substrates. However, when using the two-stage hydrolysis (acidic and alkaline steps), significantly higher amino acid solubility was observed with CE except for glycine, and proline which were equally solubilised by both SE, and CE. No significant difference was observed between reference and test diet using the SE except for tyrosine, valine, leucine, and phenylalanine, which were significantly higher solubilised in reference diet than test diet. Whereas higher solubility of valine, isoleucine, aspartic acid, and glutamic acid was observed in test diet using CE than SE. Similarly, the solubility of valine, isoleucine, and glutamic acid were higher in BSF larvae meal when CE was used. The in vivo true protein digestibility of BSF larvae meal was 99%, and 81% for the test diet containing BSF larvae meal. The results demonstrated a positive correlation (r = 0.91; p < 0.01) between salmon and commercial enzymes but overall, no significant correlation was observed for amino acid solubility between in vivo and in vitro. However, there was a strong positive correlation for protein solubility using SE (r = 0.98) than CE (r = 0.74) with the in vivo true protein digestibility. The efficiency of SE, and CE can be compared, and standardised based on DH%, and hence correlates better with the in vivo protein digestibility but not with amino acid solubilities.publishedVersio

The chemical composition of two seaweed flies (Coelopa frigida and Coelopa pilipes) reared in the laboratory

Two species of seaweed flies, Coelopa frigida and Coelopa pilipes, were reared in the laboratory and their larvae were sampled for composition of amino acids, fatty acids and elements. The larvae were grown on two different species of seaweed, Laminaria digitata and Fucus serratus. The aim was to gain knowledge on the influence of feeding media on the growth and composition of the larvae. Fucus serratus was more nutrient-dense than L. digitata, being richer in both protein and lipids, and thus led to ~70 % higher larvae growth. The larvae grown on F. serratus also had higher lipid and protein content than the larvae grown on L. digitata; F. serratus-grown larvae had ~8-9 % protein and ~18 % lipid (total fatty acids) (both values of dry matter), while the larvae grown on L. digitata had only ~7.5 % protein and ~13 % lipids. All seaweed flies had a similar and balanced amino acid composition, suitable for animal and human nutrition. The fatty acid composition was not highly affected by either insect species or feeding media, with all groups containing high concentrations of the monounsaturated fatty acid, palmitoleic acid (16:1n-7). The larvae also contained some fatty acids characteristic of marine environments, like eicosapentaenoic acid (20:5n-3), likely originating from the seaweed. Both species of seaweed fly larvae accumulated As, Cd, and Pb, but not Hg. The elevated levels of As and Cd in the larvae (highest measured concentrations 18.4 and 11.6 mg/kg, respectively, based on 12% moisture content) could potentially limit the use of seaweed fly larvae as a feed ingredient

A rapid acid hydrolysis method for the determination of chitin in fish feed supplemented with black soldier fly (Hermetia illucens) larvae

Insects are a natural source of feed for fish and have received more attention as a potential source of sustainable high-quality protein. However, contrasting results in different feeding trials have been ascribed to the chitin contained in the exoskeleton of insects and highlighted the importance of developing reliable methods for the quantification of chitin to draw meaningful conclusions about its effect on fish health. A rapid method based on the hydrolysis of chitin into glucosamine and further quantification by liquid chromatography tandem mass spectrometry is evaluated. The method offers good selectivity, linearity, limit of detection (1.08 × 10−5 % w/v or 5.38 × 10−4 % w/w), limit of quantification (3.26 × 10−5 % w/v or 1.63 × 10−3 % w/w), trueness (88.39–109.29 %) and precision (2.24–10.72 %). The quantitative method was successfully applied to real samples of fish feed supplemented with chitin from black soldier fly (Hermetia illucens) larvae.publishedVersio

Effect of dietary replacement of fish meal with insect meal on in vitro bacterial and viral induced gene response in Atlantic salmon (Salmo salar) head kidney leukocytes

Abstract With the fast growth of today's aquaculture industry, the demand for aquafeeds is expanding dramatically. Insects, which are part of the natural diet of salmonids, could represent a sustainable ingredient for aquaculture feed. The aim of the current study was to test how a partial or total replacement of dietary fishmeal with insect meal affect gene responses involved in inflammation, the eicosanoid pathway and stress response in Atlantic salmon (Salmo salar L.) in isolated head kidney leukocytes after exposure to bacterial or viral mimic. Insect meal (IM) was produced from black soldier fly (BSF, Hermetia illucens) larvae. Seawater Atlantic salmon were fed three different diets for 8 weeks; a control diet (IM0, protein from fishmeal and plant based ingredients (25:75) and lipid from fish oil and vegetable oil (33:66); and two insect-meal containing diets, IM66 and IM100, where 66 and 100% of the fishmeal protein was replaced with IM, respectively. Leukocytes were isolated from the head kidney of fish (n = 6) from each of the three dietary groups. Isolated leukocytes were seeded into culture wells and added either a bacterial mimic (lipopolysaccharide, LPS) or a viral mimic (polyinosinic acid: polycytidylic acid, poly I: C) to induce an inflammatory response. Controls (Ctl) without LPS and poly I: C were included. The transcription of interleukins IL-1β, IL-8, IL-10 and TNF-α were elevated in LPS treated leukocytes isolated from salmon fed the three dietary groups (IM0, IM66 and IM100). The inflammatory-related gene expression in head kidney cells were, however, not affected by the pre-fed substitution of fish meal with IM in the diet of salmon. Gene transcriptions of PTGDS and PTGES were neither affected by LPS, poly I: C or the experimental diets fed prior to cell isolation, while salmon fed with IM showed a lower expression of LOX5. The gene expression of TLR22 and C/EBP-β were down-regulated by the LPS treatment in the cells isolated from salmon fed insect-based diets (IM66 and IM100) compared to fish fed the IM0. Similarly, the leukocytes challenged with LPS and isolated from fish fed with IM66 and IM100 down-regulated the expression of Mn-SOD, GPx1, HSP27 and HSP70 compared to salmon fed IM0. In general, these results suggested that replacement of fishmeal with IM in the diets of Atlantic salmon had no effect on the transcription of pro-inflammatory genes in the head kidney cells. There was, however, an effect of dietary IM on the transcription of antioxidant and stress related genes in the leukocytes

Chemical characterization of 21 species of marine macroalgae common in Norwegian waters: benefits of and limitations to their potential use in food and feed

BACKGROUND: In the past few years, much effort has been invested into developing a new blue economy based on harvesting, cultivating and processing marine macroalgae in Norway. Macroalgae have high potential for a wide range of applications, e.g. as source of pharmaceuticals, production of biofuels or as food and feed. However, data on the chemical composition of macroalgae from Norwegian waters are scant. This study was designed to characterize the chemical composition of 21 algal species. Both macro- and micronutrients were analysed. Concentrations of heavy metals and the metalloid arsenic in the algae were also quantified. RESULTS: The results confirm that marine macroalgae contain nutrients which are relevant for both human and animal nutrition, the concentrations whereof are highly dependent on species. Although heavy metals and arsenic were detected in the algae studied, concentrations were mostly below maximum allowed levels set by food and feed legislation in the EU. CONCLUSION: This study provides chemical data on a wide range of algal species covering the three taxonomic groups (brown, red and green algae) and discusses both benefits of and potential limitations to their use for food and feed purposes.Chemical characterization of 21 species of marine macroalgae common in Norwegian waters: benefits of and limitations to their potential use in food and feedpublishedVersio

Potential of insect-based diets for Atlantic salmon (Salmo salar)

In the present study, we aimed to assess the effect of dietary insect meal (IM) and insect oil (IO) on growth performance, body composition and nutrient digestibility of freshwater reared Atlantic salmon. The IM and IO were produced from black soldier fly larvae (Hermetia illucens, L.; BSF) that had been grown on (1) media containing organic waste streams, or on (2) media partially containing seaweed (Ascophyllum nodosum). The feeding trial of the current study followed a factorial 2 × 3 way-ANOVA experimental design with six dietary groups of Atlantic salmon fed diets with insect-derived ingredients for 8 weeks. A typical industrial diet, with protein from fish meal and soy protein concentrate (SPC) (50:50) and lipids from fish oil and vegetable oil (33:66), was fed to a positive control group. Five experimental diets were formulated, where 85% of the dietary protein was replaced by IM and/or all the vegetable oil was replaced by IO (IM from insects grown on media 1, IO from insects grown on either media 1 (IO1) or media 2 (IO2)). Replacing the dietary fish meal and SPC with insect protein significantly reduced the apparent digestibility coefficients (ADC) of protein, lipid and all amino acids investigated, though remained highly digestible. There were, however, only small differences due to protein or lipid source in growth performance, and no effects of insect ingredients on feed intake or feed conversion ratio. Inclusion of IM-based diets significantly increased both hepatosomatic index and visceral somatic index of Atlantic salmon. Proteinase activity in the intestine was not affected by dietary inclusion of BSF larvae meal, while leucine aminopeptidase activity was lower in fish fed with insect ingredients than the control group. Whole-body protein, lipid, amino acids and minerals contents were not affected by protein or lipid source. In general, this study showed that protein meal and oil from BSF larvae hold a great potential as a source of nutrients for Atlantic salmon.publishedVersio

A meta-analysis on the nutritional value of insects in aquafeeds

A major challenge for development of sustainable aquafeeds is its dependence on fish meal and fish oil. Similarly, it is unwanted to include more plant ingredients which adds more pressure on resources like arable land, freshwater and fertilisers. New ingredients that do not require these resources but rather refine and valorise organic side streams, like insects, are being developed. Increasing evidence indicates that using insect ingredients in aquafeeds are a sustainable alternative and considerable progress has been made on this topic in the past years. The aim of this chapter is to present a comprehensive and systematic analysis of the data available on the impact of insects in aquafeeds. Systematic search, collection and selection of relevant literature from databases such as Web of Science and NCBI was performed. The literature search enabled 91 scientific papers from peer-reviewed journals, comprising a dataset of 415 experimental diets, including 35 different aquatic species and 14 insect species to be included in this meta-analysis, covering what we consider a close to complete representation of credible publications on this topic. Information on aquatic species, insect species, dietary composition (amino acids, fatty acids, proximate composition) and performance outputs (growth performance indicators and nutrient digestibility) were included in the construction of the dataset. Regression models and principal component analyses were performed on the meta-data. The results from the meta-analysis revealed a great degree of variation in the maximum threshold for insect inclusion in aquafeeds (from 4 to 37%) based on subgroups of trophic level of aquatic species, insect species used, statistical method and the output parameter. Overall, a maximum threshold of 25-30% inclusion of insects in aquafeeds for uncompromised performance is suggested. Reduction in protein digestibility, imbalanced amino acid profile and increasing levels of saturated fatty acid were identified as major factors limiting higher inclusion of insects in aquafeeds.publishedVersio