State-of-the-art on use of insects as animal feed

Computational modelling of extrusion process temperatures on the interactions between black soldier fly larvae protein and corn flour starch

Insects such as the black soldier fly (BSF) are recently being studied as food sources to address concerns about how to meet the food demand of the growing world population, as conventional production lines for meat proteins are currently unsustainable sources. Studies have been conducted evaluating the use of insect proteins to produce extruded foods such as expanded snacks and meat analogues. However, this field of study is still quite new and not much has been studied beyond digestibility and growth performance. The purpose of this work was to evaluate the compatibility of protein extracted from BSF flour with corn flour starch within an extruded balanced shrimp feed model through molecular dynamics simulations, for which cohesive energy density and solubility parameter (δ) of both components were determined. The calculations' results for the protein molecule systems yielded an average δ of 14.961 MPa0.5, while the δ for starch was calculated to be 23.166 MPa0.5. The range of difference between both δ (10 > δ > 7) suggests that the interaction of the BSF protein with corn starch is of a semi-miscible nature. These results suggest that it is possible to obtain a stable starch-protein mixture through the extrusion process.

Assessment of the USDA Biomass Harvest Trap (USDA-BHT) device as an insect harvest and mosquito surveillance tool

Insects are a promising source of high-quality protein, and the insect farming industry will lead to higher sustainability when it overcomes scaling up, cost effectiveness, and automation. In contrast to insect farming (raising and breeding insects as livestock), wild insect harvesting (collecting agricultural insect pests), may constitute a simple sustainable animal protein supplementation strategy. For wild harvest to be successful sufficient insect biomass needs to be collected while simultaneously avoiding the collection of nontarget insects. We assessed the performance of the USDA Biomass Harvest Trap (USDA-BHT) device to collect flying insect biomass and as a mosquito surveillance tool. The USDA-BHT device was compared to other suction traps commonly used for mosquito surveillance (Centers for Disease Control and Prevention (CDC) light traps, Encephalitis virus surveillance traps, and Biogents Sentinel traps). The insect biomass harvested in the USDA-BHT was statistically higher than the one harvested in the other traps, however the mosquito collections between traps were not statistically significantly different. The USDA-BHT collected some beneficial insects, although it was observed that their collection was minimized at night. These findings coupled with the fact that sorting time to separate the mosquitoes from the other collected insects was significantly longer for the USDA-BHT, indicate that the use of this device for insect biomass collection conflicts with its use as an efficient mosquito surveillance tool. Nevertheless, the device efficiently collected insect biomass, and thus can be used to generate an alternative protein source for animal feed.

Insect meal in aquafeeds: A sustainable path to enhanced mucosal immunity in fish

The mucosal surfaces of fish, including their intestines, gills, and skin, are constantly exposed to various environmental threats, such as water quality fluctuations, pollutants, and pathogens. However, various cells and microbiota closely associated with these surfaces work in tandem to create a functional protective barrier against these conditions. Recent research has shown that incorporating specific feed ingredients into fish diets can significantly boost their mucosal and general immune response. Among the various ingredients being investigated, insect meal has emerged as one of the most promising options, owing to its high protein content and immunomodulatory properties. By positively influencing the structure and function of mucosal surfaces, insect meal (IM) has the potential to enhance the overall immune status of fish. This review provides a comprehensive overview of the potential benefits of incorporating IM into aquafeed as a feed ingredient for augmenting the mucosal immune response of fish.

Live yellow mealworm (Tenebrio molitor) larvae: a promising nutritional enrichment for laying quails

The study aimed to evaluate the effect of supplementing live Tenebrio molitor (TM) larvae to laying quails (Coturnix japonica) as nutritional enrichment. Live performances, apparent digestibility of nutrients (including that of sole live TM larvae), egg physicochemical quality, sensory traits, and storage stability were considered in this experiment. Sixty laying quails were divided into 2 dietary groups (6 replicated cages/group; 5 quails/cage): a Control group received a basal diet for laying quails and a TM10 group was fed with the Control diet supplemented with live TM larvae (10% of the expected daily feed intake). For the digestibility trial, 30 laying quails were divided into 3 dietary groups: the first 2 groups were fed with the Control and TM10 diets, while the third group received ad libitum live TM larvae (TM100) as a complete replacement for the Control diet. Overall, no mortality was recorded during the trials. Quails fed TM showed a remarkable capability of digesting dietary chitin (P < 0.0001). TM100 quails showed the lowest digestibility for dry matter, crude protein, and energy, but that of ether extract was the highest (P < 0.001). The presence of live TM larvae stimulated quails' feed intake (P < 0.0001), but did not affect performance traits. Similarly, overall physicochemical quality attributes and storage stability were comparable in Control and TM10 eggs. The sensory features of quail eggs differed in TM10 vs. Control groups: TM10 eggs had the lowest overall flavor (P < 0.01), sulfur (P < 0.05) and greasy-oily (P < 0.01) intensities. Therefore, a 10% TM dietary supplementation is effective in stimulating feeding activity of quails, but it did not provide any productive improvement compared to a standard diet. Further studies should assess the possible beneficial effect of live TM supplementation on quail's gut health. The digestibility trial with the sole live TM larvae allowed to assess the specific nutritional value of this emerging feedstuff which is of utmost importance for future feed formulations.

Dietary inclusion of defatted silkworm (Bombyx mori L.) pupa meal in broiler chickens: phase feeding effects on nutritional and sensory meat quality

The present experiment was conducted to test the effect of a 4% defatted silkworm (Bombyx mori) pupae meal (SWM) incorporation into chickens' diets at different growth phases on meat quality characteristics and sensory traits. Ninety ROSS 308 day-old male broiler chickens were randomly assigned to 3 dietary groups, with 5 replicated pens/diet: the first group received a control (C) diet throughout the growing period of 42 d, the second group received a diet with 4% SWM (SWM1) during the starter phase (1-10 d) and the C diet up to slaughter, whereas the third group was fed the C diet during the starter phase and 4% SWM during the grower and finisher phases (SWM2). Diets were isonitrogenous and isoenergy, and birds had free access to feed and water throughout the experimental trial. At 42 d of age, 15 chickens/treatment were slaughtered at a commercial abattoir. Fatty acid (FA) and amino acid (AA) profiles and contents of meat, as well as its oxidative status, were determined in both breast and leg meat cuts. Also, a descriptive sensory analysis was performed on breast meat by trained panelists. Results highlighted that the SWM2 treatment increased the n-3 proportion and content in both breast and leg meat, thereby improving the omega-6/omega-3 (n-6/n-3) ratio in both cuts (P < 0.001). However, the dietary treatment had no significant effect on the oxidative status of either breast or leg meat (P > 0.05). The SWM had a limited impact on overall sensory traits of breast meat, but it contributed to improve meat tenderness in SWM-fed chickens (P < 0.01). Furthermore, SWM1 meat exhibited higher juiciness (P < 0.05) and off flavor intensity (P < 0.05) compared to the control meat. Overall, the present experiment indicated that defatted SWM holds promise as an alternative ingredient in chicken rations, ensuring satisfactory meat quality. Furthermore, administering SWM during the grower-finisher phase demonstrated beneficial effects on meat healthiness, ultimately enhancing n-3 fatty acids content and reducing the n-6/n-3 ratio.

Effects of Defatted and Hydrolyzed Black Soldier Fly Larvae Meal as an Alternative Fish Meal in Weaning Pigs

In Experiment 1, a total of eighteen crossbred ([Landrace × Yorkshire] × Duroc) barrows with an initial body weight of 6.74 ± 0.68 kg were randomly divided into three dietary treatments (one pig per cage and six replicates per treatment) and housed in metabolic cages that were equipped with a feeder and slatted floor to collect urine and feces. In Experiment 2, a total of 96 crossbred ([Landrace × Yorkshire] × Duroc) barrows with an initial body weight of 8.25 ± 0.42 kg were used in the 6-week trial. The pigs were randomly divided into three dietary treatments (three pigs per pen and eight replicates per treatment). In Experiment 1, nutrient composition of defatted black soldier fly larvae meal (BLM) was superior to that of hydrolyzed BLM but lower than that of fish meal (FM). Also, defatted BLM and FM had better apparent total track digestibility (ATTD) of crude protein (CP) and better nitrogen retention (p < 0.05) than hydrolyzed BLM, but there was no significant difference (p > 0.05) between defatted BLM and FM. In Experiment 2, defatted BLM improved (p < 0.05) average daily gain (ADG), feed conversion ratio (FCR), and feed cost per kg gain (FCG) compared with FM. Defatted BLM could replace soybean meal and fish meal as an alternative protein source for weaning pigs.

Rearing zombie flies: Laboratory culturing of the behaviourally manipulating fungal pathogen Entomophthora muscae

Insect pathogenic fungi (IPF) and insects have ubiquitous interactions in nature. The extent of these interkingdom host-pathogen interactions are both complex and diverse. Some IPF, notably of the order Entomophthorales, manipulate their species-specific host before death. The fungus-induced altered insect behaviours are sequential and can accurately be repeatedly characterised temporally, making them a valuable model for understanding the molecular and chemical underpinnings of behaviour and host-pathogen co-evolutionary biology. Here, we present methods for the isolation and laboratory culturing of the emerging behaviourally manipulating model IPF Entomophthora muscae for experimentation.•E. muscae isolation and culturing in vitro.•Establishing and maintaining an E. muscae culture in vivo in houseflies (Musca domestica).•Controlled E. muscae infections for virulence experiments and quantification of conidia discharge per cadaver.

Reproductive output and other adult life-history traits of black soldier flies grown on different organic waste and by-products

The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer's grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer's grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production.

Evaluation of Effective Energy Values of Six Protein Ingredients Fed to Beagles and Predictive Energy Equations for Protein Feedstuff

This study evaluated the nutrition composition, the nutrient digestibility, and the energy value of six protein ingredients used in pet food by the difference method in six beagles within a 7 × 6 incomplete Latin square design. The results showed that the apparent total tract digestibility of gross energy (GE) and organic matter (OM) in beagles fed the fish meal (FM) and corn gluten meal (CGM) diets was higher than for those fed the meat and bone meal (MBM), soybean meal (SBM), mealworm meal (MM), and yeast extract (YE) diets (p < 0.05). The digestible energy (DE), metabolizable energy (ME), and net energy (NE) of the MM diet were greater than the other diets, and MBM was the lowest (p < 0.05). The ME of protein ingredients was positively correlated with organic matter and negatively correlated with the ash content. The NE of protein ingredients was positively correlated with the crude protein content and negatively correlated with the ash content. The study resulted in predictive energy equations for protein ingredients that were more accurate than the NRC's predictive equation of ME when the ash content of the ingredient was more than 30% DM. In conclusion, the nutrient digestibility and energy value of corn gluten meal were similar to those of fish meal and those of soybean meal were similar to yeast extract. All predictive energy equations for six protein feedstuffs had slight differences with measured energy values.

Effect of different diet composition on the fat profile of two different black soldier fly larvae populations

Black soldier fly larvae (Hermetia illucens; BSFL) can transform organic wastes into nutritional biomass useful in animal feeding. The aim of this work was to study the effect of five diets (meat, fruit, vegetable substrates, a mix of them and control) on the profile of fatty acids (FAs) and sterols of BSFL. For a more exhaustive characterization of the nutritional properties, the profile of esterified FAs in the sn-2 position of the triglycerides, the most absorbed lipid component during animal digestion was evaluated. The dietary effect was estimated on two different Hermetia illucens populations (Greek - UTH and Italian - UNIPI). The diet affected all the lipid fractions examined. Regardless of diet, the fat was characterized mainly of lauric acid and other saturated FAs, which were found to be synthesized by the larvae, as it was not present in any of the five substrates. In general, UTH larvae contained a higher level of lipids (7.38 vs 2.48 g/100 g of larvae; P < 0.001) and saturated FAs (49.71 vs 36.10 g/100 g of Total Lipids; P < 0.001) and a lower percentage of monounsaturated FAs (14.74 vs 26.70 g/100 g of Total Lipids), C18:3n-3 (0.67 vs 1.13 g/100 g of Total Lipids; P < 0.001), and C18:2c9t11 (2.02 vs 2.80 g/100 g of Total Lipids; P < 0.001). Irrespective of the populations, BSFL reared on control and fruit substrates showed higher level of lipids (8.06 and 5.61 g/100 g of larvae, respectively), and saturated FA (38.99 and 71.19 g/100 g of Total Lipids, respectively), while the presence of meat increased the level of C20:4n-6, C20:5n-3 and C22:5n-3 (0.70, 0.13 and 0.45 g/100 g of Total Lipids, respectively). The results confirmed that BSFL accumulate phytosterols in their lipid fraction. The sterol profile was strongly influenced by the substrate on which the larvae were reared, with higher levels of cholesterol in the larvae of the meat group (38.55 mg/100 g of Total Lipids) and of stigmasterol and campesterol (9.04 and 15.23 mg/100 g of Total Lipids, respectively) in those of the vegetable group. The sterol content between the two populations was significantly different, with a higher percentage in UTH larvae (113.28 vs 34.03 mg/100 g of Total Lipids; P < 0.001). Finally, BSFLs showed a high plasticity of the lipid profile depending on both the substrate and the metabolism linked to the different populations. This variability allows the nutritional characteristics of the BSFL to be shaped by modifying the substrate, to adapt it to the technological and feeding needs to which the larvae are destined.

Microbial dynamics and vertical transmission of Escherichia coli across consecutive life stages of the black soldier fly (Hermetia illucens)

BACKGROUND

The black soldier fly (BSF, Hermetia illucens L.) is one of the most promising insects for bioconversion of organic waste, which often carry a high microbial load with potential foodborne pathogens. Although horizontal transmission (from rearing substrate to larvae) has been extensively studied, less is known about vertical transmission of microorganisms, and particularly of foodborne pathogens, across different BSF life stages.

RESULTS

This study investigated the microbial dynamics and vertical transmission of Escherichia coli across different life stages (larvae, prepupae, pupae and adults) of one BSF life cycle and its associated substrate (chicken feed) and frass, based on a combination of general microbial counts (based on culture-dependent techniques) and the bacterial community composition (based on 16S rRNA gene sequencing). Multiple interactions between the microbiota of the substrate, frass and BSF larvae were affirmed. The larvae showed relative consistency among both the microbial counts and bacterial community composition. Diversification of the bacterial communities started during the pupal stage, while most notable changes of the microbial counts and bacterial community compositions occurred during metamorphosis to adults. Furthermore, vertical transmission of E. coli was investigated after substrate inoculation with approximately 7.0 log cfu/g of kanamycin-resistant E. coli, and monitoring E. coli counts from larval to adult stage. Although the frass still contained substantial levels of E. coli (> 4.5 log cfu/g) and E. coli was taken up by the larvae, limited vertical transmission of E. coli was observed with a decreasing trend until the prepupal stage. E. coli counts were below the detection limit (1.0 log cfu/g) for all BSF samples from the end of the pupal stage and the adult stage. Additionally, substrate inoculation of E. coli did not have a substantial impact on the bacterial community composition of the substrate, frass or different BSF life stages.

CONCLUSIONS

The fluctuating microbial counts and bacterial community composition underscored the dynamic character of the microbiota of BSF life stages. Additionally, vertical transmission throughout one BSF life cycle was not observed for E. coli. Hence, these findings paved the way for future case studies on vertical transmission of foodborne pathogens across consecutive BSF life stages or other insect species.

Evaluation of the Microbial Quality of Hermetia illucens Larvae for Animal Feed and Human Consumption: Study of Different Type of Rearing Substrates

In the context of climate change and depletion of natural resources, meeting the growing demand for animal feed and human food through sufficient, nutritious, safe, and affordable sources of protein is becoming a priority. The use of Hermetia illucens, the black soldier fly (BSF), has emerged as a strategy to enhance the circularity of the agri-food chain, but its microbiological safety remains a concern. The aim of the present study was to systematically review available data on the microbiological quality of BSF and to investigate the impact of using four different rearing substrates including classic options allowed by the EU regulation (cereals, fruits, vegetables) and options not allowed by EU regulations regarding vegetable agri-food (co-products, food at shelf life, and meat). A total of 13 studies were collected and synthesized, including 910 sample results, while 102 new sample results were collected from the present experiments in three farms. Both datasets combined revealed a high level of contamination of larvae, potentially transmitted through the substrate. The main pathogenic bacteria identified were Bacillus cereus, Clostridium perfringens, Cronobacter spp., Escherichia coli, Salmonella spp., and Staphylococcus aureus coagulase-positive, while Campylobacter spp. and Listeria monocytogenes were not detected. Any of these four substrates were excluded for their use in insect rearing; however, safety concerns were confirmed and must be managed by the operators of the sector using microbial inactivation treatment after the harvest of the larvae in order to propose safe products for the market. The results obtained will guide the definition of the control criteria and optimize the following manufacturing steps.

Assessing the Socio-Economic Benefits and Costs of Insect Meal as a Fishmeal Substitute in Livestock and Aquaculture

Sustainability targets set by the United Nations, such as Zero Hunger by 2030, encourage the search for innovative solutions to enhance food production while preserving the environment. Alternative protein sources for feed, while conventional resources like soymeal and fishmeal become more expensive and scarcer, is one of the possibilities. Studies on substituting fishmeal with insect meal show promising results in terms of animal growth and feed efficiency. This paper aims to assess the socio-economic benefits and costs of insect meal substituting fishmeal in feed and to highlight the factors influencing performance most. The study evaluates the economic value of insect-based products, waste reduction, and reduced greenhouse gas emissions as socio-economic benefits. It combines empirical data derived from laboratory trials and two case studies covering black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor). Current analyses reveal negative socio-economic balances, emphasizing that reduction of operating and investment costs through upscaling and technological advancements can give a positive move, as well as factors such as current market valuations for nutrients can change significantly. Thus, a negative balance at the moment does not mean that insect rearing, and larva processing are not desirable from a long-term socio-economic perspective.

Growth, Hepatic Enzymatic Activity, and Quality of European Seabass Fed on Hermetia illucens and Poultry By-Product Meal in a Commercial Farm

Protein meals from insects in combination with poultry by-product meal appear to be promising ingredients for replacing conventional proteins in the diets of carnivorous fish. The present study explored the effects on growth performance, hepatic enzymatic activity, and fillet physical and nutritional characteristics during a 66-day feeding trial performed on European seabass. A total of 3000 fish were distributed into three tanks, where the control group was fed with a commercial diet (CG) and a second group was fed in duplicate with the experimental diet (SSH) containing 10% Hermetia illucens larva meal, 30% poultry by-product meal, and <5.5 g/100 g of feed of marine origin proteins. All fish showed good growth performance. Glucose-6-phosphate dehydrogenase, aspartate aminotransferase, and 3-hydroxyacyl-CoA dehydrogenase activities were higher in the SSH group than in the CG group. The fillet fatty acid profile was largely unaffected by diet, except for a few fatty acids. Fish fed the SSH diet had a lower C22:1n-11 content than CG, thus suggesting an increased β-oxidation. The oxidative status of muscle lipids was not affected by the diet. In conclusion, the present study showed that European seabass can be successfully fed the SSH diet for two months in a commercial setting.

The effect of Phyllanthus emblica (Amla) fruit supplementation on the rumen microbiota and its correlation with rumen fermentation in dairy cows

Introduction

Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows.

Methods

The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d).

Results

When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated.

Discussion

FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

Effect of replacing soybean meal with Hermetia illucens meal on cecal microbiota, liver transcriptome, and plasma metabolome of broilers

Despite the existence of a number of studies investigating the effect of insect meal on the growth performance of broilers, knowledge about the metabolic effects of insect meal in broilers is still scarce. Thus, the present study investigated the effect of partial replacement of soybean meal with Hermetia illucens (HI) larvae meal on the liver transcriptome, the plasma metabolome, and the cecal microbiota in broilers. For the study, 72 male one-day-old Cobb 500 broilers were divided into three groups and fed 3 different diets with either 0% (HI0), 7.5% (HI7.5), or 15% (HI15) defatted HI meal for 35 d. Each group consisted of 6 cages (replicates) with 4 broilers/cage. While body weight (BW) gain, feed intake, and feed:gain ratio did not differ between groups, breast muscle weight, carcass yield, and apparent ileal digestibility (AID) of 5 amino acids were higher in group HI15 than in group HI0 (P < 0.05). Indicators of α-diversity (Chao1 and Observed) in the cecal digesta were higher in groups HI15 and HI7.5 than in group HI0 (P < 0.05). The abundance of 5 families and 18 genera, all of which belonged to the Firmicutes phylum, in the cecal digesta differed among groups (P < 0.05). Concentrations of butyric acid, valeric acid, and isobutyric acid in the cecal digesta were lower in group HI15 than in the other 2 groups (P < 0.05), whereas those of total and other short-chain fatty acids were not different between groups. Liver transcriptomics revealed a total of 70 and 61 differentially expressed transcripts between groups HI15 vs. HI0 and between groups HI7.5 vs. HI0, respectively, (P < 0.05). Targeted metabolomics identified 138 metabolites, most of which were triglyceride species, being different between the 3 groups (FDR < 0.05). According to this study, dietary inclusion of HI larvae meal has no detrimental impact but increases breast muscle weight and carcass weight in broilers suggesting that HI larvae meal can be recommended as a sustainable alternative protein source for broilers.

Material flow analysis and global warming potential assessment of an industrial insect-based bioconversion plant using housefly larvae

The significant increase in the demand for biomass waste treatment after garbage classification has led to housefly larvae treatment becoming an attractive treatment option. It can provide a source of protein while treating biomass waste, which means that nutrients can be returned to the natural food chain. However, the performance of this technology in terms of its environmental impacts is still unclear, particularly with regards to global warming potential (GWP).This study used a life cycle assessment (LCA) approach to assess a housefly larvae treatment plant with a treatment capacity of 50 tons of biomass waste per day. The LCA results showed that the 95% confidence intervals for the GWP in summer and winter were determined to be 24.46-32.81 kg CO2 equivalent (CO2-eq)/ton biomass waste and 5.37-10.08 kg CO2-eq/ton biomass waste, respectively. The greater GWP value in summer is due to the longer ventilation time and higher ventilation intensity in summer, which consumes more power. The main GWP contributions are from (1) electricity needs (accounting for 78.6% of emissions in summer and 70.2% in winter) and (2) product substitution by mature housefly larvae and compost (both summer and winter accounting for 96.8% of carbon reduction).

Assessing Substrate Utilization and Bioconversion Efficiency of Black Soldier Fly (Hermetia illucens) Larvae: Effect of Diet Composition on Growth and Development Temperature

Black soldier fly larvae (BSFL) can utilize food by-products or residues for growth, benefiting farm animal's diets' production sustainability. The experiment aimed to assess the effect of different substrate compositions on larval growth, chemical composition, and substrate temperature. BSFL were allocated to one of the four diets (control, vegetable, carnivorous, and omnivorous) for the entire experiment (8 days). The temperature was measured twice daily using a thermal-imaging camera, and the accumulated degree hours (ADH) was calculated. The results showed that the larvae fed the vegetable diet exhibited a significantly reduced growth performance, with a biomass reduction of 26.3% compared to the control diet; furthermore, vegetable-fed larvae showed a lower dry matter content (-30% compared to the average of other diets) due to lower fat content (-65% compared to average of other diets). The nutritional composition of larvae fed an omnivorous diet was similar to larvae fed a high-quality substrate diet (control diet-chicken feed), indicating that the omnivorous diet could be an ideal solution for rearing BSFL larvae; however, the current European legislation prohibits the use of animal meal. The study also revealed that substrate temperatures did not have a discernible influence on larval growth, further emphasizing the importance of diet in BSFL rearing strategies.

Evaluating the Efficiency of Black Soldier Fly (Hermetia illucens) Larvae in Converting Mackerel Head Waste into Valuable Resources

The seafood processing industry generates significant waste, including mackerel heads (MH), constituting 20-32% of total waste. This study explored the potential of utilizing MH as a feed source for black soldier fly larvae (BSF larvae). BSF larvae are known for their ability to efficiently convert organic materials into nutrient-rich biomass. Five concentrations of MH (0, 10, 20, 30, 40, and 50% in chicken feed) were fed to BSF larvae for eight days. After harvesting, their growth, MH conversion efficiency, nutritional content, and heavy metals reduction potential were measured. BSF larvae showed optimal growth when fed with a feed containing 20% MH, resulting in a 14.36-fold increase in weight compared to the control group, as determined by the Fisher's Least Significant Difference Test. BSF larvae maintained a survival rate of 99.33%. With the lowest feed conversion ratio (FCR) of 2.09 at 20% MH, feed efficiency was improved by up to 65.15%, and feed reduction up to 73.53%. MH enhanced lipid and protein content in BSF larvae. Furthermore, BSF larvae in this study showed higher polyunsaturated fatty acids (PUFA), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as other amino acids which are required for breeding animals. The current study highlights the potential of MH as a feed source for BSF larvae, improving nutritional biomass. It also suggests BSF larvae as an eco-friendly option for handling seafood processing waste and as an alternative feed source for animals.

Dietary Tenebrio molitor larvae meal effects on cellular stress responses, antioxidant status and intermediate metabolism of Oncorhynchus mykiss

In the context of evaluating the impact of environmentally friendly and sustainably produced alternative protein sources in fish feed, the present study's aim was to examine the overall physiological stress response in one of the main fish species of European freshwater aquaculture, Oncorhynchus mykiss (rainbow trout), following the partial substitution of fish meal (FM) with a Tenebrio molitor (TM) (yellow mealworm) full-fat meal. In total, 222 rainbow trout individuals (115.2 ± 14.2 g) were allocated randomly into six tanks, three per dietary treatment, and were fed a formulated diet containing 60% yellow mealworm (TM60) compared to a control diet without insect meal (TM0). Both diets contained equal amounts of crude protein, dry matter and, lipid content, while the FM in TM60 was 100 g kg-1 corresponding to the one seventh of the TM0. Heat shock response (HSR), MAPK signalling, cell death pathways (apoptosis and autophagy), antioxidant defence mechanisms, and intermediate metabolism were evaluated. In general, HSR and MAPK signalling were activated in response to the inclusion of T. molitor. Moreover, triggering of apoptotic and autophagic processes and the onset of antioxidant defence mechanisms underlined the existence of physiological stress. Despite the apparent dietary-induced stress, rainbow trout in the present study exhibited no mortality and no significant effects regarding growth performance parameters. Specifically, TM60 dietary inclusion resulted in no changes in final body weight, weight gain, and specific growth rate. However, feed intake depicted a statistically significant decrease in TM60 fish compared to TM0 individuals. Nevertheless, nutrient stress should be considered a limiting factor regarding the utilization of T. molitor in O. mykiss diet due to the associated risks for health and welfare.

Larval Frass of Hermetia illucens as Organic Fertilizer: Composition and Beneficial Effects on Different Crops

Hermetia illucens has received a lot of attention as its larval stage can grow on organic substrates, even those that are decomposing. Black soldier fly breeding provides a variety of valuable products, including frass, a mixture of larval excrements, larval exuviae, and leftover feedstock, that can be used as a fertilizer in agriculture. Organic fertilizers, such as frass, bringing beneficial bacteria and organic materials into the soil, improves its health and fertility. This comprehensive review delves into a comparative analysis of frass derived from larvae fed on different substrates. The composition of micro- and macro-nutrients, pH levels, organic matter content, electrical conductivity, moisture levels, and the proportion of dry matter are under consideration. The effect of different feeding substrates on the presence of potentially beneficial bacteria for plant growth within the frass is also reported. A critical feature examined in this review is the post-application beneficial impacts of frass on crops, highlighting the agricultural benefits and drawbacks of introducing Hermetia illucens frass into cultivation operations. One notable feature of this review is the categorization of the crops studied into distinct groups, which is useful to simplify comparisons in future research.

Black soldier fly larvae meal supplementation in a low protein diet reduced performance, but improved nitrogen efficiency and intestinal morphology of duck

OBJECTIVE

Reduced crude protein (CP) diets offer potential benefits such as optimized feed efficiency, reduced expenses, and lower environmental impact. The objective of this study was to evaluate black soldier fly larvae (BSFL) meal on a low-protein diet for duck performance, blood biochemical, intestinal morphology, gastrointestinal development, and litter.

METHODS

The experiment was conducted for 42 days. A total of 210-day-old male hybrid ducklings (5 replicate pens, 7 ducks per pen) were randomly assigned to 6 dietary treatments (3×2 factorial arrangements) in randomized design. The factors were CP level (18%, 16%, 14%) and protein source feed soybean meals (SBM), black soldier fly larvae meals (BSFLM).

RESULTS

Reduced dietary CP levels significantly decreased growth performance, feed intake, the percentage of nitrogen, pH (p<0.05), and tended to suppress ammonia in litter (p = 0.088); increased lipid concentration; and enhanced relative weight of gastrointestinal tracts (p<0.05). In addition, dietary BSFL as a source of protein feed significantly increased lipid concentration and impacted lowering villus height and crypt depth on jejunum (p<0.05).

CONCLUSION

In conclusion, the use of BSFLM in a low-protein diet was found to have a detrimental effect on growth performance. However, the reduction of 2% CP levels in SBM did not have a significant impact on growth performance but decreased nitrogen and ammonia concentrations.

Larval performance of Zophobas morio (F.) (Coleoptera: Tenebrionidae) on various diets enriched with post-distillation residues and essential oils of aromatic and medicinal plants

The increasing demands for resources driven by the global population necessitate exploring sustainable alternatives for affordable animal protein over the use of traditional protein sources. Insects, with their high protein content, offer a promising solution, especially when reared on agricultural post-distillation residues for enhanced sustainability and cost-effectiveness. We assessed the development of Zophobas morio (F.) (Coleoptera: Tenebrionidae) larvae on diets enriched with essential oils and post-distillation residues from Greek aromatic and medicinal plants. Two aromatic plant mixtures (A and B) were examined. Mixture A consisted of post-distillation residues, while Mixture B incorporated these residues along with essential oils. Insect rearing diets were enriched with different proportions (10, 20, and 30 %) of these mixtures, with wheat bran serving as the control. Enrichment positively influenced larval development without compromising survival. Larval weight remained unchanged with Mixture A, but improved with Mixture B. No adverse effects were detected in the case of the enriched diets, although higher concentrations of Mixture B prolonged development time.

The Role of Insects in Sustainable Animal Feed Production for Environmentally Friendly Agriculture: A Review

The growing demand for animal protein, the efficient use of land and water, and the limitations of non-renewable energy sources highlight the global importance of edible insects. This paper provides an overview of the key issues regarding the role of edible insects in sustainable feed production and environmentally friendly agriculture. The indispensable ecological services provided by insects are discussed, as well as the farming, products, and nutritional value of edible insects. A representative selection of the literature reviewing major insect species' chemical compositions and nutritional value is also presented. The use of insect-derived feeds for animal production is presented in detail and discussed for the major terrestrial livestock and aquaculture groups.

Diet replacement with whole insect larvae affects intestinal morphology and microbiota of broiler chickens

Insect-based diets are gaining interest as potential ingredients in improving poultry gut health. This study assessed the dietary treatment with whole dried Tenebrio molitor larvae (TM) on broiler chickens' gut microbiota and morphology. 120 Ross-308 broilers received treated diets with 5% (TM5) and 10% (TM10) replacement ratio in a 35-day trial. Intestinal histomorphometry was assessed, as well as claudin-3 expression pattern and ileal and caecal digesta for microbial community diversity. Null hypothesis was tested with two-way ANOVA considering the intestinal segment and diet as main factors. The TM5 group presented higher villi in the duodenum and ileum compared to the other two (P < 0.001), while treated groups showed shallower crypts in the duodenum (P < 0.001) and deeper in the jejunum and ileum than the control (P < 0.001). Treatments increased the caecal Firmicutes/Bacteroidetes ratio and led to significant changes at the genus level. While Lactobacilli survived in the caecum, a significant reduction was evident in the ileum of both groups, mainly owed to L. aviarius. Staphylococci and Methanobrevibacter significantly increased in the ileum of the TM5 group. Results suggest that dietary supplementation with whole dried TM larvae has no adverse effect on the intestinal epithelium formation and positively affects bacterial population richness and diversity.

Rearing methods of four insect species intended as feed, food, and food ingredients: a review

Over the past 2 decades, the potential of insects as food and feed has been recognized globally. Insects as feed ingredients can improve sustainability because of their lower greenhouse gas emissions and their potential to transform organic wastes into high-quality feed rich in nutrients. However, currently, the practical use of insects as food or feed is limited by the high costs of insect production. A great deal of effort is required to improve the rearing technology necessary to establish the principles of insect farming. Several insect species have become industrialized using existing methods of production. The most common industrialized insect species intended as feed and food include the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae); the house cricket, Acheta domesticus L. (Orthoptera: Gryllidae); the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae); and the house fly, Musca domestica L. (Diptera: Muscidae). This review focuses on describing the existing rearing methods for these 4 insect species, which may provide a basis for future research to enhance insect production capabilities.

Local circular economy: BSF insect rearing in the Italian Agri-Food Industry

With a growing population, both food and waste production will increase. There is an urgent need for innovative ways of valorizing waste. The black soldier fly (Hermetia illucens L.) efficiently converts agri-food by-products (BPs) into high-quality materials; its rearing process yields larvae (BSFL) rich in fat and protein for feed purposes, with "frass" acting as organic fertilizer. While the insect rearing sector is expanding, few producers use BPs. Therefore, a case study approach was adopted to evaluate the potential for establishing an Italian BSFL production plant on BPs available on the territory. After contacting more than 115 agri-food companies (maximum 100 km from the BSFL plant), they were classified based on sector, distance, size, and BPs (quantity, seasonality, management). BPs with a low value (fruit and vegetable residues) were treated as waste, associated with costs and low valorization. By merging the available BPs on the territory and following the literature on BSFL nutritional needs' two diets (Scenario BSFL) were created, assessing their suitability comparing them to the current full-scale plant diet (Scenario 0). The exploitation of BPs for BSFL rearing reduced local waste production by 52 % compared to conventional composting (Scenario 0). In addition, integrating BPs into the larval feed formulation increased BSFL production value (+47 times). These results highlight the potential of locally-based insect rearing to valorize BPs and create a network of sustainable actors within the agri-food industry. Further investigations are needed to improve the connection between agri-food and insect industrial activities, expanding this framework to other regions.

Grinding as a slaughter method for farmed black soldier fly (Hermetia illucens) larvae: Empirical recommendations to achieve instantaneous killing

At least 200 billion black soldier fly (Hermetia illucens) larvae (BSFL) are reared each year as food and feed, and the insect farming industry is projected to grow rapidly. Despite interest by consumers, producers, and legislators, no empirical evidence exists to guide producers in practicing humane - or instantaneous - slaughter for these novel mini-livestock. BSFL may be slaughtered via freezing, boiling, grinding, or other methods; however standard operating procedures (SOPs) and equipment design may affect the likelihood of instantaneous death using these methods. We tested how larval body size and particle size plate hole diameter affect the likelihood of instantaneous death for black soldier fly larvae that are slaughtered using a standard meat grinder. Larval body size did not affect the likelihood of instantaneous death for larvae that are 106-175 mg in mass. However, particle size plate hole diameter had a significant effect on the likelihood of instantaneous death, with only 54% of larvae experiencing an instant death when using the largest particle size plate (12-mm hole diameter) compared to 84% using the smallest particle size plate (2.55 mm). However, a higher percentage of instantaneous death (up to 99%) could be achieved by reducing the proportion of larvae that become stuck in the machine. We conclude by outlining specific recommendations to support producers in achieving a 99% instantaneous death rate through specific SOPs to be used with similarly designed machines. We also develop a protocol for producers that wish to test their own grinding SOPs.

Investigation of the suitability of 3 insect meals as protein sources for rainbow trout (Oncorhynchus mykiss)

An in vivo trial was conducted to determine the apparent digestibility coefficients (ADCs) of insect meals for rainbow trout, Oncorhynchus mykiss. Rainbow trout (approximately 370 g ± 23 g, mean ± SD initial weight) were stocked 25 per tank into 400-liter tanks. Fish were fed a reference diet, or 1 of 5 test diets created by blending the reference diet in a 70:30 ratio (dry-weight basis) with menhaden fish meal (MFM), 2 house cricket (Acheta domesticus) meals (cricket A and cricket B), Galleria mellonella meal, and yellow mealworm (Tenebrio molitor) meal. Diets were assigned to 3 replicate tanks of fish and fed twice daily for 14 days prior to fecal collection. Ingredients, diets, and fecal matter were analyzed in duplicate for proximate, mineral, and amino acid composition. House cricket meals were 67.3% and 69.0% protein (CP) and 16.6% and 17.1% lipid (CL), for house cricket A and B, respectively. Yellow mealworm meal contained 56.5% CP and 27.7% CL, and G. mellonella larvae meal contained 32.5% CP and 54.2% CL. Protein ADCs were 78.9 for G. mellonella larvae meal, 78.0 for yellow mealworm meal, and 76.5 for house cricket A and not different from the MFM protein ADC of 76.6, while house cricket B protein ADC was 65.8 and was significantly lower than the MFM protein ADC (F = 7.39; df = 4,14; P = 0.0049). Together, these nutritional values suggest house crickets, and yellow mealworms show promise as alternative protein sources in salmonid feeds, with the potential of G. mellonella as an alternative lipid source.

Live black soldier fly (Hermetia illucens) larvae in feed for laying hens: effects on hen gut microbiota and behavior

This study examined the effects of including live black soldier fly (BSF, Hermetia illucens) larvae in the diet of laying hens on gut microbiota, and the association between microbiota and fearfulness. A total of 40 Bovans White laying hens were individually housed and fed 1 of 4 dietary treatments that provided 0, 10, 20%, or ad libitum daily dietary portions of live BSF larvae for 12 wk. Cecum microbiota was collected at the end of the experiment and sequenced. Behavioral fear responses to novel objects and open field tests on the same hens were compared against results from gut microbiota analyses. The results showed that the bacteria genera Enterococcus, Parabacteroides, and Ruminococcus torques group were positively associated with increased dietary portion of live larvae, while Lactobacillus, Faecalibacterium, Bifidobacterium, Subdoligranulum, and Butyricicoccus were negatively associated with larvae in the diet. Inclusion of larvae did not affect fear behavior, but the relative abundance of Lachnospiraceae CHKCI001 and Erysipelatoclostridium was associated with fear-related behaviors. Further studies are needed to determine whether the change in gut microbiota affects fearfulness in the long-term.

Effect of moisture content on larval gut microbiome and the conversion of pig manure by black soldier fly

The study investigated the influence of varied moisture levels in pig manure on the gut microbiome of black soldier fly larvae (BSFL) and their waste conversion efficiency. This encompassed alterations in nutrient components of both BSFL and pig manure, diversity and characterization of the BSFL gut microbiota, and the reciprocal effects between the BSFL gut microbiota and their growth performance and nutrient composition. Additionally, the investigation delved into the changes in the bacterial community and the presence of potential pathogenic bacteria in pig manure. An initial mixture of fresh pig manure and wheat bran was prepared with a 60 % moisture content (Group A). Distilled water was subsequently added to adjust the moisture levels, resulting in mixtures with 65 % (Group B), 70 % (Group C), and 75 % (Group D) moisture content. Each group underwent BSFL digestion over ten days. Groups C (3.87 ± 0.05 mg/worm) and D (3.97 ± 0.08 mg/worm) showed significantly higher bioconversion efficiencies and enhanced BSFL growth compared to Groups A (2.66 ± 0.21 mg/worm) and B (3.09 ± 0.09 mg/worm) (P < 0.05). A 75 % moisture level was identified as ideal, positively influencing fecal conversion efficiency (FCE) (9.57 ± 0.14 %), crude fat intake (8.92 ± 0.56 %), protein (46.60 ± 0.54 %), and total phosphorus (1.37 ± 0.08 %) from pig manure, and subsequent nutrient accumulation in BSFLs. A decline in larval crude ash content indicated higher organic matter and an increased pig manure conversion rate with elevated moisture. High-throughput sequencing and diversity analyses confirmed different moisture contents influenced the BSFL gut microbiota. Bacteroidetes (32.7-62.0 %), Proteobacteria (6.8-29.3 %), Firmicutes (5.8-23.4 %), and Actinobacteria (1.9-29.0 %) were predominant phyla. A 75 % moisture content significantly impacted the BSFL biomass conversion and growth performance. Additionally, Larval feces met non-hazardous fertilizer standards, according to NY-525 (2012).

Production of safe cyanobacterial biomass for animal feed using wastewater and drinking water treatment residuals

The growing interest in microalgae and cyanobacteria biomass as an alternative to traditional animal feed is hindered by high production costs. Using wastewater (WW) as a cultivation medium could offer a solution, but this approach risks introducing harmful substances into the biomass, leading to significant safety concerns. In this study, we addressed these challenges by selectively extracting nitrates and phosphates from WW using drinking water treatment residuals (DWTR) and chitosan. This method achieved peak adsorption capacities of 4.4 mg/g for nitrate and 6.1 mg/g for phosphate with a 2.5 wt% chitosan blend combined with DWTR-nitrogen. Subsequently, these extracted nutrients were employed to cultivate Spirulina platensis, yielding a biomass productivity rate of 0.15 g/L/d, which is comparable to rates achieved with commercial nutrients. By substituting commercial nutrients with nitrate and phosphate from WW, we can achieve a 18 % reduction in the culture medium cost. While the cultivated biomass was initially nitrogen-deficient due to low nitrate levels, it proved to be protein-rich, accounting for 50 % of its dry weight, and contained a high concentration of free amino acids (1260 mg/g), encompassing all essential amino acids. Both in vitro and in vivo toxicity tests affirmed the biomass's safety for use as an animal feed component. Future research should aim to enhance the economic feasibility of this alternative feed source by developing efficient adsorbents, utilizing cost-effective reagents, and implementing nutrient reuse strategies in spent mediums.

Evaluation of Growth Performance and Environmental Impact of Hermetia illucens Larvae Reared on Coffee Silverskins Enriched with Schizochytrium limacinum or Isochrysis galbana Microalgae

Hermetia illucens is a promising insect due to its ability to convert low-value substrates as food chain by-products into highly nutritious feed. Its feeding and nutrition are important issues. The aim of this work was to investigate the effect of different substrates consisting of coffee silverskin, a by-product of the roasting process, enriched with different inclusions of microalgae (5%, 10%, 20%, and 25%), Schizochytrium limacinum, and Isochrysis galbana, combined with the assessment of environmental sustainability by LCA. In general, the addition of microalgae led to an increase in larval growth performance due to the higher content of protein and lipids, although S. limacinum showed the best results with respect to larvae fed with coffee silverskin enriched with I. galbana. A higher prepupal weight was observed in larvae fed with 10%, 20%, and 25% S. limacinum; shorter development times in larvae fed with 25% of both S. limacinum and I. galbana; and a higher growth rate in larvae fed with 25% S. limacinum. The 10% S. limacinum inclusion was only slightly different from the higher inclusions. Furthermore, 10% of S. limacinum achieved the best waste reduction index. The greater the inclusion of microalgae, the greater the environmental impact of larval production. Therefore, the addition of 10% S. limacinum appears to be the best compromise for larval rearing, especially considering that a higher inclusion of microalgae did not yield additional benefits in terms of the nutritional value of H. illucens prepupae.

Big opportunities for tiny bugs: rush to boost laying hen performance using black soldier fly larvae meal

Rising feed cost challenges due to expensive conventional protein sources continue to make headlines in Africa causing drops in profit margins. We assessed the impact of insect (Hermetia illucens Linnaeus larvae meal, HILM) protein as a substitute for soybean meal and sunflower seed cake on layer chicken performance and profitability. Our results showed that apart from the growers, chicks (12.37 g/bird) and layer hens (2.02 g/bird) fed diets with 75% HILM inclusion levels had significantly higher average daily weight gain. The average daily feed intake (ADFI) and feed conversion ratio (FCR) varied significantly when the chicks and layer hens were provided with the HILM-based diets. For the chicks and layer hens, the lowest ADFI and FCR were observed in birds subjected to diets with 75% and 100% HILM compared to the growers fed diets with 50% HILM. Significantly higher egg production was observed for layer hens fed diets containing 75% of HILM throughout the first (87.41%) and second (83.05%) phase production cycles. Layer hens fed HILM-based diets had a 3-10% increase in egg laying percentage. There was higher profit margins when birds were fed diets containing 75% of HILM (~1.83 and 5.98 US$ per bird), which mirrored the return on investment estimated at 63.95% and 33.36% for the pullets (growers) and laying hen, respectively. Our findings demonstrate that diets with 75% HILM provided optimum growth performance, reduced feeding costs, increased weight gain and egg production as well as improved economic returns for commercial on-farm poultry production systems.

Flight toward Sustainability in Poultry Nutrition with Black Soldier Fly Larvae

Black soldier fly larvae (BSFL), Hermetia illucens (L.) (Diptera: Stratiomyidae), have emerged as a promising feed ingredient in broiler chicken diets, known for their high protein content, nutritional richness, and environmental sustainability. This review examines the effects of integrating BSFL into broiler feeds, focusing on aspects such as growth performance, nutrient digestibility, physiological responses, and immune health. The ability of BSFL to transform waste into valuable biomass rich in proteins and lipids underscores their efficiency and ecological benefits. Protein levels in BSFL can range from 32% to 53%, varying with growth stage and diet, offering a robust source of amino acids essential for muscle development and growth in broilers. While the chitin in BSFL poses questions regarding digestibility, the overall impact on nutrient utilization is generally favorable. The inclusion of BSFL in diets has been shown to enhance growth rates, feed efficiency, and carcass quality in broilers, with the larvae's balanced amino acid profile being particularly advantageous for muscle development. BSFL may also support gut health and immunity in broilers due to its bioactive components, potentially influencing the gut's microbial composition and enhancing nutrient absorption and overall health. Moreover, the capacity of BSFL to efficiently convert organic waste into protein highlights their role as an environmentally sustainable protein source for broiler nutrition. Nonetheless, further research is necessary to fully understand the long-term effects of BSFL, ideal inclusion rates, and the impact of varying larval diets and rearing conditions. It is crucial for poultry producers to consult nutritionists and comply with local regulations when incorporating new feed ingredients like BSFL into poultry diets.

Black soldier fly (Hermetia illucens) larvae meal improves quail growth performance

The aim of the present study was to determine the nutritional value of black soldier fly (BSF) larvae meal for quail (experiment I) and the dose-response effects of BSF levels on growth performance, relative organ weight, and body composition of growing quails (experiment II). In experiment I, 100 35-day-old quail were distributed in a completely randomized design, with two treatments (reference and test diet) and 10 replicates. The experimental period consisted of 5 days of adaptation, followed by 5 days of total excreta collection. The experimental feed consisted of a reference diet and a test diet formulated with 850 g/kg reference diet and 150 g/kg BSF. In experiment II, 1000 1-day-old quail were distributed in a completely randomized design, with five dietary levels of BSF (0, 25, 50, 75, and 100 g/kg). At 42 days of age, birds were slaughtered, and the relative organ weight and body composition were determined. Apparent metabolizable energy values corrected for nitrogen retention of BSF meal were 13.8 MJ/kg. Across the starter (1-14 days) and overall period (1-42 days), increasing BSF levels had a quadratic effect on body weight and body weight gain. Feed conversion ratio was quadratically affected during the starter phase and linearly reduced over the overall period. Additionally, the BSF levels linearly decreased the small intestine's relative weight at 42 days and had a quadratic effect on the rate of protein deposition. We concluded that the inclusion of 100 g/kg BSF meal improves feed conversion ratio for growing quail.

Fat from Hermetia illucens Alters the Cecal Gut Microbiome and Lowers Hepatic Triglyceride Concentration in Comparison to Palm Oil in Obese Zucker Rats

BACKGROUND

Palm oil (PO) is the most widely utilized plant oil for food production. Owing to the great ecologic problems associated with PO production, sustainably produced fats, such as insect fat, might be a suitable alternative.

OBJECTIVES

The hypothesis was tested that fat from Hermetia illucens larvae (HF) compared with PO and soybean oil (SO) has no adverse effects on hepatic lipid metabolism, plasma metabolome, and cecal microbiome in obese Zucker rats.

METHODS

Thirty male obese Zucker rats were randomly assigned to 3 groups (SO, PO, HF; n = 10 rats/group) and fed 3 different semisynthetic diets containing either SO, PO, or HF as the main fat source for 4 wk. The effects were evaluated by measurement of liver and plasma lipid concentrations, liver transcriptomics, targeted plasma metabolomics, and cecal microbiomics.

RESULTS

Supplementation of HF reduced hepatic triglyceride concentration and messenger ribonucleic acid concentrations of selected genes involved in fatty acid and triglyceride synthesis in comparison to PO (P < 0.05). Pairwise comparison of the Simpson index and Jaccard index showed a higher cecal microbial α- and β-diversity in rats fed the HF diet than in rats fed the PO diet (P = 0.015 and P = 0.027), but no difference between rats fed the diets with SO or PO. Taxonomic analysis of the cecal microbial community revealed a lower abundance of Clostridium_sensu_stricto_1 and a higher abundance of Blautia, Mucispirillum, Anaerotruncus, Harryflintia, and Peptococcus in rats supplemented with HF than in rats supplemented with PO (P < 0.05).

CONCLUSIONS

HF, compared with PO, has liver lipid-lowering effects in obese Zucker rats, which may be caused by a shift in the gut microbial community. Thus, HF might serve as a sustainably produced fat alternative to PO for food production.

Growth and Hepatopancreas Health of Juvenile Chinese Mitten Crab (Eriocheir sinensis) Fed Different Levels of Black Soldier Fly (Hermetia illucens) Larvae Meal for Fish Meal Replacement

A 56-day feeding trial assessed the effects of black soldier fly larvae meal (BSFLM) on the growth performance and hepatopancreas health of juvenile Eriocheir sinensis. Six isoproteic and isolipidic diets with 0% (FM), 10% (BSFLM10), 20% (BSFLM20), 30% (BSFLM30), 40% (BSFLM40), or 50% (BSFLM50) replacement of fish meal by BSFLM were formulated. Compared to FM, replacing 10%-40% of fish meal with BSFLM did not significantly affect the weight gain rate (WGR) or specific growth rate (SGR), while BSFLM50 significantly decreased the WGR and SGR. Crabs fed BSFLM50 had significantly lower T-AOC activity than those fed other diets, and crabs fed BSFLM30, BSFLM40, or BSFLM50 had significantly lower activities of antioxidant enzymes (SOD and GSH-Px) in the hepatopancreas than those fed FM or BSFLM10. Compared to FM, BSFLM10, BSFLM20, and BSFLM30 did not affect the relative expression of genes related to the nonspecific immunity, while BSFLM40 and BSFLM50 upregulated the relative expression of these genes. Furthermore, histological analysis showed that the hepatopancreas was deformed in the BSFLM50 group, with widened lumens and loss of basal membrane integrity. In summary, BSFLM replacing 50% of fish meal reduced growth and structural damage to the hepatopancreas. An immune response was activated when the replacement level was over 30%. Therefore, the replacement level of dietary fish meal by BSFLM is recommended to be not more than 30% of the juvenile E. sinensis feed.

Antimicrobial activity of lipids extracted from Hermetia illucens reared on different substrates

As the problem of antimicrobial resistance is constantly increasing, there is a renewed interest in antimicrobial products derived from natural sources, particularly obtained from innovative and eco-friendly materials. Insect lipids, due to their fatty acid composition, can be classified as natural antimicrobial compounds. In order to assess the antibacterial efficacy of Hermetia illucens lipids, we extracted this component from the larval stage, fed on different substrates and we characterized it. Moreover, we analyzed the fatty acid composition of the feeding substrate, to determine if and how it could affect the antimicrobial activity of the lipid component. The antimicrobial activity was evaluated against Gram-positive Micrococcus flavus and Gram-negative bacteria Escherichia coli. Analyzing the fatty acid profiles of larval lipids that showed activity against the two bacterial strains, we detected significant differences for C4:0, C10:0, C16:1, C18:3 n3 (ALA), and C20:1. The strongest antimicrobial activity was verified against Micrococcus flavus by lipids extracted from larvae reared on strawberry, tangerine, and fresh manure substrates, with growth inhibition zones ranged from 1.38 to 1.51 mm, while only the rearing on manure showed the effect against Escherichia coli. Notably, the fatty acid profile of H. illucens seems to not be really influenced by the substrate fatty acid profile, except for C18:0 and C18:2 CIS n6 (LA). This implies that other factors, such as the rearing conditions, larval development stages, and other nutrients such as carbohydrates, affect the amount of fatty acids in insects. KEY POINTS: • Feeding substrates influence larval lipids and fatty acids (FA) • Generally, there is no direct correlation between substrate FAs and the same larvae FAs • Specific FAs influence more the antimicrobial effect of BSF lipids.

Alternative and Sustainable Protein Sources in Pig Diet: A Review

The search for alternative protein sources to soybean meal (SBM) in animal feeding is a strategic objective to reduce production costs and contribute to sustainable animal production. Spirulina, due to the high protein content, has emerged as a potential cost-effective, sustainable, viable, and high-nutritional-value food resource for many animal species. Insect larvae (Tenebrio molitor and Hermetia illucens) are also considered potential alternatives to SBM, given their high edible percentage of almost 100%, as well as a protein value higher than that of vegetable proteins. Rapeseed meal and grain legumes, such as fava beans, peas, lupins, and chickpea, can also be used as locally producible protein ingredients. This study reviews the nutritional value of these potential alternatives to SBM in pig diets, and their effects on animal performance, digestion, immune system, and the physicochemical and sensorial characteristics of meat, including processed pork products. The limits on their use in pig feeding are also reviewed to indicate gaps to be filled in future research on the supplementation level of these potential alternative protein sources in pig diets.

Assessing the feasibility, safety, and nutritional quality of using wild-caught pest flies in animal feed

Studies have investigated the potential of using farmed insects in animal feeds; however, little research has been done using wild-caught insects for this purpose. Concerns about inadequate quantities collected, environmental impacts, and the spread of pathogens contribute to the preferred utilization of farmed insects. Nevertheless, by harvesting certain pest species from intensified agricultural operations, producers could provide their animals with affordable and sustainable protein sources while also reducing pest populations. This study explores the possibility of collecting large quantities of pest flies from livestock operations and analyzes the flies' nutritional content, potential pathogen load, and various disinfection methods. Using a newly designed mass collection-trapping device, we collected 5 kg of biomass over 13 wk, primarily house flies, from a poultry facility. While a substantial number of pests were removed from the environment, there was no reduction in the fly population. Short-read sequencing was used to compare the bacterial communities carried by flies from differing source populations, and the bacterial species present in the fly samples varied based on farm type and collection time. Drying and milling the wild-caught flies as well as applying an additional heat treatment significantly reduced the number of culturable bacteria present in or on the flies, though their pathogenicity remains unknown. Importantly, these disinfection methods did not affect the nutritional value of the processed flies. Further research is necessary to fully assess the safety and viability of integrating wild-caught insects into livestock feed; however, these data show promising results in favor of such a system.

Effect of a Probiotic Beverage Enriched with Cricket Proteins on the Gut Microbiota: Composition of Gut and Correlation with Nutritional Parameters

The health and balance of the gut microbiota are known to be linked to diet composition and source, with fermented products and dietary proteins potentially providing an exceptional advantage for the gut. The purpose of this study was to evaluate the effect of protein hydrolysis, using a probiotic beverage enriched with either cricket protein (CP) or cricket protein hydrolysates (CP.Hs), on the composition of the gut microbiota of rats. Taxonomic characterization of the gut microbiota in fecal samples was carried out after a 14-day nutritional study to identify modifications induced by a CP- and CP.H-enriched fermented probiotic product. The results showed no significant differences (p > 0.05) in the diversity and richness of the gut microbiota among the groups fed with casein (positive control), CP-enriched, and fermented CP.H-enriched probiotic beverages; however, the overall composition of the microbiota was altered, with significant modifications in the relative abundance of several bacterial families and genera. In addition, fermented CP.H-enriched probiotic beverages could be related to the decrease in the number of potential pathogens such as Enterococcaceae. The association of gut microbiota with the nutritional parameters was determined and the results showed that digestibility and the protein efficiency ratio (PER) were highly associated with the abundance of several taxa.

Effects of Fishmeal Substitution with Mealworm Meals (Tenebrio molitor and Alphitobius diaperinus) on the Growth, Physiobiochemical Response, Digesta Microbiome, and Immune Genes Expression of Atlantic Salmon (Salmo salar)

A 12-week growth trial was conducted to assess the effects of mealworm meals, as a substitution for fishmeal, on the growth, physiobiochemical responses, digesta microbiome, and immune-related genes expression of Atlantic salmon (Salmo salar). Twenty Atlantic salmon parr (38.5 ± 0.1 g, initial weight) were stocked into each of 16 tanks in a recirculating aquaculture system. A fishmeal-based diet (100% FM) was used as the control treatment and was compared with three test diets where: (1) fishmeal was partially (50%) replaced with defatted mealworm meal, Tenebrio molitor (50% DMM), (2) fishmeal was fully replaced with defatted mealworm meal (100% DMM), and (3) fishmeal was partially replaced with whole lesser mealworm meal, Alphitobius diaperinus (50% WMM). All substitutions were done on a crude protein basis. Each of the four experimental diets was evaluated in quadruplicate tanks as part of randomized design. The results indicated that Atlantic salmon showed high survival (greater or equal to 98.8%), and no significant difference in final growth, feed efficiency, feces stability and condition indices. Hepatosomatic index was lower in fish fed 100% DMM and 50% WMM when compared to fish fed the control diet (100% FM). Whole-body proximate and amino acid compositions were not statistically different between treatments, while essential fatty acids, including linolenic, eicosapentaenoic acid, and homo-a-linolenic, were lower in fish fed 100% DMM. Plasma parameters (total protein, alanine aminotransferase, alkaline phosphatase, and total iron-binding capacity), hepatic peroxide, and antioxidant enzymes were not significantly affected by dietary substitutions, whereas plasma immunoglobulin M showed significantly higher levels in fish fed 50% DMM and 100% DMM when compared to fish fed the control diet (100% FM). The inclusion of mealworm meals significantly impacted the overall microbiome composition but not the richness and evenness of the salmon digesta microbiomes compared to control. The most common genus in all treatments was Pseudomonas, which has been previously shown to have both commensal and pathogenic members. The relative expressions of growth (IGF-I) and protein synthesis (TIPRL) were not significantly different between the treatments, whereas immunoglobulin genes (IgM, IgD, and IgT) were significantly upregulated in fish fed the DMM diets when compared to fish fed the control diet. Overall, this study suggests that the mealworm meals tested could be suitable alternatives to fishmeal in the diet of Atlantic salmon.

Acceptance and forage utilization responses of steers consuming low-quality forage and supplemented black soldier fly larvae as a novel feed

As the insect-rearing industry scales in the United States and other developed nations, it has the potential to create multiple product streams (e.g., oil and protein-rich biomass) for existing markets. Black soldier fly larvae (BSFL; Hermetia illucens) has been identified as a potential livestock feed because it is not expected to compete in the human food sector and its production has a lesser environmental footprint than that of conventional feeds. Existing research on BSFL as feed focuses on full-fat BSFL for poultry and aquaculture. Therefore, the objective of our experiment was to evaluate the viability of defatted BSFL as an alternative protein source for beef cattle consuming forage. Procedures were approved by Texas State University IACUC (#7726). Two experiments were conducted using ruminally cannulated beef steers fed low-quality forage in 5 × 5 Latin squares. Experiment 1 assessed consumption of BSFL as a protein supplement and included five 5-d periods with 3-d for washout and 2-d for measurement of supplement intake and preference. There were five treatments delivered in addition to the basal forage: 100% soybean meal (SBM); 75% SBM/25% BSFL; 50% SBM/50% BSFL; 25% SBM/75% BSFL; and 100% BSFL. Supplement and forage intake did not differ between treatments (P ≥ 0.45) nor was there a treatment × day interaction (P ≥ 0.45). Experiment 2 evaluated the effect of BSFL supplementation on forage (5.3% crude protein) intake and digestion and included five 14-d periods with 8-d for treatment adaptation, 5-d for measurement of intake and digestion, and 1-d for determination of ruminal fermentation. There were four treatments of supplemental BSFL provided at graded N levels: 0, 50, 100, or 150 mg N/kg BW and one level of SBM at 100 mg N/kg BW. Increasing provision of BSFL linearly increased forage organic matter (OM) intake (P = 0.04), total OM intake (P < 0.01), total digestible OM intake (P < 0.01), dry matter digestibility (P = 0.01), and OM digestibility (P = 0.02). There were no significant differences (P ≥ 0.17) in intake or digestibility between levels of BSFL and SBM. Ultimately, defatted BSFL has potential to replace conventional feeds as a protein supplement without sacrificing forage utilization.

Insect-based agri-food waste valorization: Agricultural applications and roles of insect gut microbiota

Meeting the demands of the growing population requires increased food and feed production, leading to higher levels of agri-food waste. As this type of waste seriously threatens public health and the environment, novel approaches to waste management should be developed. Insects have been proposed as efficient agents for biorefining waste, producing biomass that can be used for commercial products. However, challenges in achieving optimal outcomes and maximizing beneficial results remain. Microbial symbionts associated with insects are known to have a critical role in the development, fitness, and versatility of insects, and as such, they can be utilized as targets for the optimization of agri-food waste insect-based biorefinery systems. This review discusses insect-based biorefineries, focusing on the agricultural applications of edible insects, mainly as animal feed and organic fertilizers. We also describe the interplay between agri-food waste-utilizing insects and associated microbiota and the microbial contribution in enhancing insect growth, development, and involvement in organic waste bioconversion processes. The potential contribution of insect gut microbiota in eliminating pathogens, toxins, and pollutants and microbe-mediated approaches for enhancing insect growth and the bioconversion of organic waste are also discussed. The present review outlines the benefits of using insects in agri-food and organic waste biorefinery systems, describes the roles of insect-associated microbial symbionts in waste bioconversion processes, and highlights the potential of such biorefinery systems in addressing the current agri-food waste-related challenges.

Effects of plant-based proteins and handling stress on intestinal mucus microbiota in rainbow trout

Via 16S rRNA gene amplicon sequencing, this study explores whether the gut mucus microbiota of rainbow trout is affected by the interaction of a plant-protein-based diet and a daily handling stressor (chasing with a fishing net) across two genetic lines (A, B). Initial body weights of fish from lines A and B were 124.7 g and 147.2 g, respectively. Fish were fed 1.5% of body weight per day for 59 days either of two experimental diets, differing in their fish meal [fishmeal-based diet (F): 35%, plant-based diet (V): 7%] and plant-based protein content (diet F: 47%, diet V: 73%). No diet- or stress-related effect on fish performance was observed at the end of the trial. However, we found significantly increased observed ASVs in the intestinal mucus of fish fed diet F compared to diet V. No significant differences in Shannon diversity could be observed between treatments. The autochthonous microbiota in fish fed with diet V was dominated by representatives of the genera Mycoplasma, Cetobacterium, and Ruminococcaceae, whereas Enterobacteriaceae and Photobacterium were significantly associated with diet F. The mucus bacteria in both genetic lines were significantly separated by diet, but neither by stress nor an interaction, as obtained via PERMANOVA. However, pairwise comparisons revealed that the diet effect was only significant in stressed fish. Therefore, our findings indicate that the mucus-associated microbiota is primarily modulated by the protein source, but this modulation is mediated by the stress status of the fish.

Cellulose-degrading bacteria improve conversion efficiency in the co-digestion of dairy and chicken manure by black soldier fly larvae

Black soldier fly larvae (BSFL) have potential utility in converting livestock manure into larval biomass as a protein source for livestock feed. However, BSFL have limited ability to convert dairy manure (DM) rich in lignocellulose. Our previous research demonstrated that feeding BSFL with mixtures of 40% dairy manure and 60% chicken manure (DM40) provides a novel strategy for significantly improving their efficiency in converting DM. However, the mechanisms underlying the efficient conversion of DM40 by BSFL are unclear. In this study, we conducted a holistic study on the taxonomic stucture and potential functions of microbiota in the larval gut and manure during the DM and DM40 conversion by BSFL, as well as the effects of BSFL on cellulosic biodegradation and biomass production. Results showed that BSFL can consume cellulose and other nutrients more effectively and harvest more biomass in a shorter conversion cycle in the DM40 system. The larval gut in the DM40 system yielded a higher microbiota complexity. Bacillus and Amphibacillus in the BSFL gut were strongly correlated with the larval cellulose degradation capacity. Furthermore, in vitro screening results for culturable cellulolytic microbes from the larval guts showed that the DM40 system isolated more cellulolytic microbes. A key bacterial strain (DM40L-LB110; Bacillus subtilis) with high cellulase activity from the larval gut of DM40 was validated for potential industrial applications. Therefore, mixing an appropriate proportion of chicken manure into DM increased the abundance of intestinal bacteria (Bacillus and Amphibacillus) producing cellulase and improved the digestion ability (particularly cellulose degradation) of BSFL to cellulose-rich manure through changes in microbial communities composition in intestine. This study reveals the microecological mechanisms underlying the high-efficiency conversion of cellulose-rich manure by BSFL and provide potential applications for the large-scale cellulose-rich wastes conversion by intestinal microbes combined with BSFL.

Waste to value: Global perspective on the impact of entomocomposting on environmental health, greenhouse gas mitigation and soil bioremediation

The innovative use of insects to recycle low-value organic waste into value-added products such as food, feed and other products with a low ecological footprint has attracted rapid attention globally. The insect frass (a combination unconsumed substrate, faeces, and exuviae) contains substantial amounts of nutrients and beneficial microbes that could utilised as fertilizer. We analyse research trends and report on the production, nutrient quality, maturity and hygiene status of insect-composted organic fertilizer (ICOF) generated from different organic wastes, and their influence on soil fertility, pest and pathogen suppression, and crop productivity. Lastly, we discuss the impact of entomocomposting on greenhouse gas mitigation and provide critical analysis on the regulatory aspects of entomocomposting, and utilization and commercialisation ICOF products. This information should be critical to inform research and policy decisions aimed at developing and promoting appropriate standards and guidelines for quality production, sustainable utilization, and successful integration of entomocompost into existing fertilizer supply chains and cropping systems.

Fats and major fatty acids present in edible insects utilised as food and livestock feed

Common food sources including meat, fish and vegetables are the main source of fats and fatty acids required by human body. Edible insects such as worms, locusts, termites, crickets and flies have also been identified as a potential source of essential fatty acids since they are highly documented to be rich in unsaturated fatty acids such as α-linolenic and linoleic acids which are vital for the normal functioning of the body. The approval of insects as edible food by the European Union has sparked research interest in their potential to form part of human and animal diets due to their abundant protein, amino acids, fats, and minerals. However, little attention has been given to the importance and health benefits of lipids and fatty acids present in edible insects consumed by human and animals. This article aims to review the biological significance of essential fatty acids found in edible insects. The accumulation of fats and essential fatty acids present in edible insects were identified and described based on recommended levels required in human diets. Furthermore, the health benefits associated with insect oils as well as different processing techniques that could influence the quality of fats and fatty acid in edible insects were discussed.