Inclusion Of Insect Meal Research Articles

Effects of Dietary Protein to Lipid Ratio and Insect Meal on Growth Performance, Feed Utilization, and the Gut Microbiome of Lake Whitefish (Coregonus clupeaformis)

Wild stocks of lake whitefish (Coregonus clupeaformis) are declining in the Great Lakes, and there is a lack of information on their nutritional requirements and gut health indicators to effectively culture them in an aquaculture setting. The aim of this study was to evaluate the growth performance, nutrient utilization, and gut microbiome of lake whitefish fed varying protein:lipid ratios with and without the inclusion of insect meal from black soldier fly (BSF). In total, 450 lake whitefish (301 ± 10 g) were fed one of five diets with differing protein‐to‐lipid ratios (high‐protein 54%, low‐protein 48%, high‐lipid 18%, or low‐lipid 12%), and an additional commercial control rainbow trout diet (Bluewater commercial control [BCC]). High‐protein diets included 5% BSF meal to explore its potential to partially replace fishmeal in the diet. After 16 weeks at 8.5°C, growth performance and nutrient digestibility were the highest for lake whitefish fed the high‐protein–high‐lipid (HPHL) and BCC diets, while the feed conversion ratio (FCR) was numerically lowest for the HPHL. Protein and energy retention, and lipid digestibility were highest for fish fed the HPHL and BCC diets, while the BCC diet had the highest lipid retained, concomitant with high viscerosomatic index (VSI). High lipid in fish, especially in the viscera that is removed during processing, is not desirable, thus the HPHL diet is recommended. The gut microbiome was dominated by Proteobacteria, specifically by the genera of Shewanella and Aeromonas, although feeding high‐lipid diets resulted in the lowest alpha diversity, but was not significant. These results are novel for this species, and we recommend that lake whitefish diets should be formulated to have a minimum 54:18 protein‐to‐lipid ratio. The results from this study provide baseline information on the nutrition and gut microbiome of lake whitefish, which can be used to develop a species‐specific feed rather than feeding them rainbow trout feed. However, further work on targeted breeding and genetic selection of broodstock, together with diet optimization, is needed to improve the growth performance and nutrient utilization in order to enable an effective, economical, and environmentally sustainable culture of lake whitefish.

Partial or complete replacement of soybean meal with black soldier fly larvae meal improves feed efficiency in laying hens between 22 to 30 weeks of age

Abstract The European Commission recently authorised the inclusion of insect meal in poultry feed. Black soldier fly larvae meal (BSF) has comparable nutritional value to soybean meal (SBM) and higher calcium content, making it an attractive alternative protein source for laying hens While a few studies have explored this objective, inconsistent results have been reported, likely due to variations in hen age, breed, husbandry systems, and sunflower meal composition across studies, making it difficult to draw clear conclusions. We hypothesised that partial or complete replacement of SBM with BSF has no adverse effects on egg production and quality in laying hens at the initiation of laying (22-30 weeks of age). This study consisted of three dietary treatments and nine replicates per treatment. Diets were a control diet, and two diets containing 5% (BSF5%) and 10% (BSF10%). The experimental unit was a pen (100 × 200 × 200 cm) of 14 Brown Nick laying hens resembling an aviary setting. We found that complete replacement of SBM with BSF10% in the diet of laying hens improved feed efficiency attributed to a lower feed intake in comparison to laying hens fed the BSF5% or the control diets, while production performance, body weight, and egg quality were maintained and the colour of the egg yolk increased. Therefore, replacing SBM with up to 10% BSF in brown laying hens in aviary pens at the initiation of laying had no adverse effects on production performance, chemical and physical characteristics, and sensory attributes of eggs. Maintaining production and egg quality with a lower intake of nutrients requires further investigation.

Expanding the menu for New Zealand farmed abalone: dietary inclusion of insect meal and grape marc (effects on gastrointestinal microbiome, digestive morphology, and muscle metabolome)

ABSTRACT Limited supply of sustainable feed ingredients is a significant concern for future aquaculture practices. Alternative ingredients, such as insect meal and grape marc, are suitable for aquaculture nutrition due to their nutritional profile and more sustainable production methods. This study assessed the effect of dietary insect meal and grape marc on gut microbial composition, digestive system morphology, and muscle metabolome of Haliotis iris. Juvenile abalone were fed four encapsulated experimental diets with varying levels of insect meal/grape marc and a commercial feed for 165 days in a commercial farm. The gut health of abalone was evaluated through histopathology, and 16S rRNA amplicon libraries through Illumina MiSeq sequencing. The abalone metabolome was evaluated through gas chromatography-mass spectrometry (GC-MS). Results showed that animals had good intestinal condition across all dietary treatments. Microbiome analysis revealed increased relative abundances of bacteria (Firmicutes and Fusobacterium) associated with the breakdown of polysaccharides in diets including insect meal and grape marc. Metabolite profile variations indicate that the inclusion of insect meal and grape marc favoured fatty acid metabolism and amino acid catabolism, respectively. This study provides foundation to produce more sustainable feeds including insect meal and grape marc without affecting the gut and overall health of abalone.

Sustainable Aquafeed Formulations Containing Insect Larval Meal and Grape Marc for the New Zealand Farmed Abalone.

The aquaculture industry has been criticised for the excessive use of fish meal (FM) in feeds due to the utilisation of wild fish in the formulation and the exacerbation of overfishing marine resources. Land-based abalone aquaculture mainly uses commercial feeds (CFs) to promote faster growth, which include FM as a primary protein component. Alternative ingredients, such as insect meal (IM) and grape marc (GM) are potential candidates for FM replacement due to their suitable nutritional profile and sustainable production. This paper reports on a novel nutritional approach for the New Zealand farmed abalone, which replaces FM with IM by 10% and includes a waste by-product (GM) by 30% as a potential prebiotic source. The study was performed in two stages: (a) physico-chemical determination of diets delivered in an alginate matrix (experimental diets) and their stability in seawater compared to CF and (b) evaluation of growth and feed intake for the New Zealand black-foot abalone. There were significant differences between experimental diets and CF in terms of sinking rate, particle weight, and microscopic observations. Water stability of the experimental diets was increased by 50% in 24 and 48 hr compared to CF, producing less solid waste, and potentially reducing cleaning efforts in the farm. The inclusion of IM and GM did not compromise overall animal growth or their feed conversion ratio, however, further evaluation need to be explored in the future research. The findings revealed that the developed encapsulated feeds are a more stable food delivery method for Haliotis iris compared to the CF. Furthermore, both IM and GM can be included in feed formulations as a more sustainable strategy without compromising weight and shell gains in the abalone farming.

Evaluation of black soldier fly larvae meal as a functional feed ingredient in Atlantic salmon (Salmo salar) under farm-like conditions

Atlantic salmon (Salmo salar) were fed diets containing black soldier fly larvae (BSFL) meal at two inclusion levels for 13 months in open sea-cages. BSFL meal replaced plant-based ingredients and dietary insect meal inclusion levels were at 5% and 10%. A commercial salmon diet was fed as a control diet. Fish were reared from ~173 g to ~ 4 kg and were randomly distributed into nine open sea-cages with ~6000 salmon/cage (12×12 m2; 1900 m3). Fish from the sea-cages were sampled at two time points (mid and final samplings) to study the dietary effects of BSFL meal on the general health and welfare. Monthly assessments of sea-lice and gill score were conducted to evaluate the overall well-being of the salmon. The findings from the current study revealed that dietary inclusion of BSFL meal up to 10% did not have any significant effects in general growth, welfare or survival. However, significant positive response was observed in the general skin mucosal, hematological, and gene expression profiles of salmon. Notably, the group of salmon fed with 5% BSFL meal showed a significant decrease in plasma aspartate transaminase and alanine transaminase. Also, a significantly higher expression of interleukin1β in both skin and gill along with upregulation of matrix metallopeptidase9 and mucin18 in gill were observed in salmon fed BSFL at 5%, which aided in increased immune responses. Apart from that, this group had significantly higher mucus secretions, decreased cortisol response and increased number of erythrocytes. Furthermore, the delousing stress had a significant effect on the plasma cortisol, and these responses were independent of the dietary effect. Moreover, these immune responses behaved differently at different fish size and time points, acknowledging the influence of various factors in immune modulation. Overall, the findings from this study showed the effects of dietary BSFL meal to modulate the immune status of salmon. This study aims to fill the existing knowledge gaps regarding the impact of incorporating BSFL meal as a functional feed ingredient into the salmon diet on health and immune status replicating real farm conditions.

Effects of insect meal and grape marc in the nutritional profile, growth, and digestibility of juvenile New Zealand farmed abalone

Generally, one of the most significant bottlenecks of land-based abalone aquaculture is the high cost of the feed, which is associated with the use of wild fish stocks to produce fish meal. Fish meal is a key ingredient used in aquaculture feeds due to its nutritional profile and palatability. Alternative ingredients, such as insect meal and grape marc, are potential candidates to be included in aquafeeds due to their suitable nutritional profile and more sustainable production. This study aimed to evaluate the effect of insect meal and grape marc on growth and nutritional profile using abalone as an animal model in a feeding trial for 165 days. Proximate analyses were used to identify nutritional variations in abalone tissue and faecal matter, and liquid chromatography-mass spectrometry and gas chromatography mass-spectrometry analyses were utilised to characterise amino acid and fatty acid composition. Results showed a 95% survival for all treatments. The inclusion of insect meal and grape marc did not affect the protein proportions of abalone tissues, but differences were found in the carbohydrate and lipid proportions. The inclusion of insect meal and grape marc significantly affected levels of amino acids L-histidine, L-methionine, and L-phenylalanine, and fatty acids oleic acid, linoleaidic acid, palmitic acid, palmitoleic acid, and α-linolenic suggesting a correlation between the feed source and fatty acid tissue composition. This work provides promising results for future optimisation of abalone diets including more affordable and sustainable alternative ingredients.

Effect of Dietary Insect Meal and Grape Marc Inclusion on Flavor Volatile Compounds and Shell Color of Juvenile Abalone Haliotis iris.

Almost 60% of the fish meal produced globally is used in aquaculture feeds. Fish meal production relies on finite wild-marine resources and is considered as an unsustainable ingredient. Insect meal (IM) is considered a sustainable source with high levels of protein suitable for growth promotion. Grape marc (GM) is a waste byproduct of the winery industry rich in pigments with antioxidant capacity. However, the inclusion of both ingredients can affect the flavor of the meat of abalone and the color of the shell due to different nutritional profiles. The aim of this study was to evaluate the effect of the dietary inclusion of IM and GM on the flavor volatile compounds and shell color of the juvenile Haliotis iris in a 165-days feeding trial. Abalone were offered four experimental diets with different levels of IM and GM inclusion and a commercial diet (no IM or GM). Soft bodies of abalone were used to characterize volatile compounds using solid-phase microextraction gas chromatography-mass spectrometry, and color changes were analyzed in ground powder of abalone shells using color spectrophotometry 400-700 nm (visible). The results showed 18 volatile compounds significantly different among the dietary treatments. The inclusion of IM did not significantly affect the flavor volatile compounds detected, whereas the inclusion of GM reduced volatile compounds associated with lipid-peroxidation in abalone meat. The inclusion of IM and GM did not significantly affect the lightness nor the yellowness, blueness, redness, and greenness of the ground shells. The supplementation of abalone feeds with GM can help to reduce off-flavour compounds which may extend shelf-life of raw abalone meat.

Dietary protein, lipid and insect meal on growth, plasma biochemistry and hepatic immune expression of lake whitefish (Coregonus clupeaformis)

Studies are lacking that investigate the dietary nutrient requirements of lake whitefish (Coregonus clupeaformis), a newly farmed fish species in Ontario, Canada. Dietary levels of protein and lipid must be optimized to ensure high growth performance for the commercial success of this species. Additionally, the inclusion of insect meal in the diet may improve growth and immune response. The objective of this study was to evaluate the effects of dietary protein:lipid ratios and insect meal as a feed additive on the growth performance and hepatic immune function of juvenile lake whitefish (301 ± 10 g). A 16-week (112 day) trial was performed with five diets including a commercial control diet (BCC), and four experimental diets with high or low levels of protein (54 and 48%, respectively) and lipid (18 and 12%, respectively). The high protein dietary groups contained 5% of full-fat black soldier fly larvae (Hermetia illucens). Fish weights, viscera, liver, and blood were collected for further analysis. Specific growth rate, thermal growth coefficient and weight gain were significantly higher in fish fed with the BCC and high protein high lipid (HPHL) diets. However, viscerosomatic index was found to be significantly higher in fish fed the BCC diet, thus HPHL is more optimal for non-visceral weight gain. Higher levels of plasma phosphorus, aspartate aminotransferase and potassium indicated poor growth and stress in fish fed low lipid diets. Relative expression of HSP70, involved in cellular repair, was significantly downregulated in fish fed high lipid diets, and no effects were found on the expression of innate immune and oxidative stress genes. Also, IL8 (CXCL8) and catalase were upregulated (non-significant) in fish fed the HPHL diet with the largest weight gain. No effects of insects were found on growth, plasma biochemistry or gene expression, which suggests 5% dietary inclusion was too low. Overall, we recommend a HPHL diet for the cultivation of lake whitefish based on improved growth performance, low viscera weight, improved plasma biochemistry and downregulation of cellular repair genes.

Effect of Dietary Incorporation of Yellow Mealworm as a Partial Fishmeal Replacer on Growth, Metabolism, and Intestinal Histomorphology in Juvenile Meagre (Argyrosomus regius).

Efforts have been made to find alternatives to fish meal (FM), as the sustainability of aquaculture depends on it. Insect meal (IM) is a potential candidate to partially replace FM, being more sustainable and economically viable. In this experimental trial, three diets were tested with different yellow mealworm incorporation: a control diet with no IM, a diet with an inclusion of 10% IM (Ins10), and a diet with an incorporation of 20% IM (Ins20). The diets were tested on 10.5 g meagre for 47 days. The results showed that an IM inclusion higher than 10% affected both growth (2.6 vs. 2.2) and FCR (1.5 vs. 1.9) of meagre juveniles. However, this reduction in growth did not result from lower protein retention or changes in muscle fibre area or density. Little differences were observed in the activity of pancreatic and intestinal enzymes except for aminopeptidase total activity which was higher in the control and Ins10 compared to Ins20 (3847 vs. 3540 mU/mg protein), suggesting no limitations in protein synthesis. Also, the alkaline phosphatase intestinal maturation index was higher in the control group compared to the IM groups (437 vs. 296). On the contrary, several differences were also found in the proteolytic activity in the hepatic and muscle tissues of meagre juveniles fed the Ins10 diet. The inclusion of IM had no impact on intestine histomorphology but changes were detected in the enterocytes of fish from control and Ins10 which showed hypervacuolization and nucleus misplacement compared to the Ins20 treatment. Nevertheless, a higher percentage of Vibrionaceae was recorded for meagre fed on the Ins20 diet. Since no signs of inflammation were observed in the distal intestine, this suggests IM incorporation could have had an important impact on intestinal health due to its antimicrobial properties. This is supported by an increase in the haematocrit in the treatments where IM was added (20 to 25%). In conclusion, incorporations of IM at percentages up to 10% do not seem to have a negative impact on meagre performance at this age but can enhance the fish immune system and protection against intestinal inflammation.

Defatted black soldier fly (Hermetia illucens) in pikeperch (Sander lucioperca) diets: Effects on growth performance, nutrient digestibility, fillet quality, economic and environmental sustainability.

The use of insect meal in aquafeed formulations has recently gained attention. Detailed knowledge about the inclusion levels for pikeperch (Sander lucioperca), a promising candidate for intensive aquaculture in Europe remains, however, fragmented. In the present study, 4 isoproteic (45% dry matter) and isoenergetic (21MJ/kg) diets were formulated, including a control diet (H0) containing 30% fishmeal (FM) on an as-fed basis and the other 3 diets in which FM protein was replaced by defatted black soldier fly (Hemetia illucens) meal (HIM) at 25%, 50%, and 100% (diet abbreviation H9, H18 and H36, corresponding to an inclusion level of 9%, 18% and 36%, respectively). The feeding trial was performed in triplicate groups of 50 juvenile pikeperch (mean weight, 68.7g) fed with experimental diets for 84d during which the growth performance, nutrient digestibility, fillet quality and economic and environmental sustainability of rearing pikeperch were evaluated. Our findings indicated that pikeperch in H0, H9, and H18 groups displayed better results regarding growth performance indices, except for survival rate where no significant difference among groups was recorded (P= 0.642). A significantly lower organ-somatic index, including hepatosomatic, viscerosomatic and perivisceral fat index, was found in fish in H18 groups than other groups (P<0.05). Inclusion of HIM affected the digestibility of the nutrients and resulted in an almost linear reduction in the apparent digestibility coefficient of dry matter and protein. Concerning the fillet quality, dietary HIM negatively affected the protein and ash contents of the fish fillets, while the crude fat remained unchanged. Dietary HIM did not significantly modify total saturated, monounsaturated and polyunsaturated fatty acids in the fillets of fed pikeperch (P>0.05) but did reduce total n-3 fatty acids (P=0.001) and increased total n-6 (P<0.001). Increasing inclusion levels of HIM reduced the environmental impacts associated with fish in-to-fish out ratio but entailed heavy burdens on energy use and eutrophication. Low and moderate inclusion levels of HIM did not negatively affect land use and water use compared to an HIM-free diet (P>0.05). The addition of HIM at a level as low as 9% elicited a similar carbon footprint to that of the control diet. The economic conversion ratio and economic profit index were negatively affected at increased insect meal inclusion levels. This study has shown that the incorporation of HIM in feed formulations for pikeperch is feasible at inclusion levels of 18% without adverse effects on growth performance parameters. The feasibility also highlighted the environmental benefits associated with land use and marine resources required to produce farmed fish.

Black Soldier Fly Full-Fat Meal in Atlantic Salmon Nutrition – Part A: Effects on Growth Performance, Feed Utilization, Selected Nutriphysiological Traits and Production Sustainability in Fries

Abstract Black soldier fly larva meal (BSFM) application as an innovative feed material has been developed in aquaculture nutrition. However, recent scientific literature is still lacking in the case of insect meal effects on different stages of salmonid fish, and the vast majority of research is focused on farmed Atlantic salmon. Therefore, the holistic approach was undertaken in the cycle of two studies carried out: on fries and pre-smolts. This study aimed to evaluate the effect of fish meal (FM) replacement by full-fat BSFM in Atlantic salmon fry diets on the growth performance, feed utilization, crude protein and crude fat digestibility, somatic indices, histomorphology of intestines, and environmental sustainability. Additionally, pellet quality was assessed. Two experiments were performed on 360 Atlantic salmon fries – each of which lasted 60 days. For the first experiment, 240 individuals were distributed to four experimental groups: six replicates (tanks) per group and 10 fish per tank. For the second experiment, 120 individuals were distributed to four experimental groups: three replicates (tanks) per group and 10 fish per tank were used. The following groups were applied: CON – without the addition of full-fat BSFM and with 39% FM; BSFM5 – with 5% addition of full-fat BSFM and 36.1% FM; BSFM10 – with 10% full-fat BSFM and 33.3% FM; BSFM15 – with 15% addition of full-fat BSFM and 30.3% FM. The present study showed satisfactory results of BSFM inclusion at the levels of 5% and 10% as a replacement for fish meal in feeds for Atlantic salmon fries. No negative effects on growth performance, feed utilization, protein and fat digestibility, or intestinal structure were recorded. Simultaneously, insect meal inclusion in Atlantic salmon diets significantly improved the environmental sustainability of the feed. In the case of BSFM15, decreases in body weight gain, protein lipid efficiency ratio, and lipid efficiency ratio, as well as increases in feed conversion ratio, were observed. Therefore, the use of shares higher than 10% of BSFM in Atlantic salmon fries may not be recommended.

Towards a more sustainable feed for New Zealand farmed abalone: Inclusion of insect meal and grape pomace as alternative ingredients

Abalone, locally called pāua, is a valuable export product in New Zealand, contributing between NZD $50-60 million annually towards the country’s export economy [1]. Generally, one of the most significant bottlenecks of land-based abalone aquaculture is the high cost of the feed, which can be up to 50% of the production cost [2]. The high price has been attributed to fish meal, which is a key ingredient used in aquaculture feeds due to its excellent amino acid profile and palatability. However, fish meal use has been questioned due to the utilisation of wild fish to feed farmed fish and the exacerbation of overfishing marine resources [3]. Alternative ingredients, such as insects and winery waste products, are potential candidates as protein replacements due to their suitable nutritional profile and more sustainable production. This study aims to 1) develop and characterise alternative formulated feed for pāua (Haliotis iris) using insect meal and grape pomace and 2) evaluate the nutritional and growth alterations in juvenile pāua receiving different formulated feeds for 6 months. Proximate analysis is used to identify nutritional variations in body and faecal matter, and liquid/gas chromatography–mass spectrometry (LC/GC–MS) analyses are utilised to characterise amino acid and fatty acid profiles in tissue samples. Results show a high animal survival rate of 95% and increased seawater stability of experimental diets compared to a commercial feed. Nutritional analyses show no significant variations in animal tissues in terms of protein proportions and amino acid profiles, but differences were found in the lipid proportions and fatty acid profiles. This research will present the evidence to support the potential use of insect meal and grape marc as fishmeal replacements in abalone feeds, leading to a more sustainable aquaculture.

Apparent Digestibility Coefficients of Black Soldier Fly (Hermetia illucens), Yellow Mealworm (Tenebrio molitor), and Blue Bottle Fly (Calliphora vicina) Insects for Juvenile African Catfish Hybrids (Clarias gariepinus × Heterobranchus longifilis).

A digestibility trial was conducted with African catfish hybrid juveniles in order to determine the apparent digestibility coefficients (ADCs) of different nutrients. The experimental diets contained defatted black soldier fly (BSL), yellow mealworm (MW), or fully fat blue bottle fly (BBF) meals, in a 70 : 30 ratio between the control diet and the tested insect meals. The indirect method for the digestibility study was performed using 0.1% yttrium oxide as an inert marker. Fish juveniles of 217.4 ± 9.5 g initial weight were distributed in 1 m3 tanks (75 fish/tank) of a recirculating aquaculture system (RAS), in triplicates, and fed until satiation for 18 days. The average final weight of the fish was 346 ± 35.8 g. The ADCs of the dry matter, protein, lipid, chitin, ash, phosphorus, amino acids, fatty acids, and gross energy for the test ingredients and diets were calculated. A six-month storage test was carried out to evaluate the shelf life of the experimental diets, while the peroxidation and microbiological status of the diets were also assessed. The ADC values of the test diets differed significantly (p < 0.001) compared to those of the control for most of the nutrients. Altogether, the BSL diet was significantly more digestible for protein, fat, ash, and phosphorus than the control diet but less digestible for essential amino acids. Significant differences were found between the ADCs of the different insect meals evaluated (p < 0.001) for practically all nutritional fractions analyzed. The African catfish hybrids were able to digest BSL and BBF more efficiently than MW, and the calculated ADC values agreed with those of other fish species. The lower ADCs of the tested MW meal correlated (p < 0.05) with the markedly higher acid detergent fiber (ADF) levels present in the MW meal and MW diet. Microbiological evaluation of the feeds revealed that mesophilic aerobic bacteria in the BSL feed were 2-3 orders of magnitude more abundant than those in the other diets and their numbers significantly increased during storage. Overall, BSL and BBF proved to be potential feed ingredients for African catfish juveniles and the shelf life of the produced diets with 30% inclusion of insect meal retained the required quality during a six-month period of storage.

Economic viability of insect meal as a novel ingredient in diets for broiler chickens

The study aimed to evaluate the economic efficiency of supplementation of Tenebrio molitor meal in the diet for broilers, from 1 to 35 days of age. For that, data from a preliminary study were used to evaluate the inclusion of T. molitor meal in the broiler production performance. Four treatments were adopted: a control group and three experimental diets with 4, 8 and 12% levels of inclusion of this meal. The economic viability indicators were calculated considering the cost of the feed (R$/kg), the price of live broiler (R$/kg), feed intake (kg) and body weight (kg) of the birds. The feed cost increased proportionally with the inclusion of insect meal in poultry diets while the gross margin decreased from 93 to 98%, with 4 to 12% of inclusion of this ingredient, compared to the control diet. In the previous study, the level of 4% resulted in better performance of the birds, so, to enable the inclusion of 4% meal in the diet, this ingredient should be priced at R$ 4.53/kg.

Oxidative metabolism of gut and innate immune status in skin and blood of tench (Tinca tinca) fed with different insect meals (Hermetia illucens and Tenebrio molitor)

Searching alternative protein sources in fish feeds is essential for aquaculture sustainability, and insect-based meals arise as a promising option. The objective of this study is to assess the possible impact that the inclusion of insect meal on the tench (Tinca tinca) diet would have on the innate immune system in mucus and blood, as well as on the oxidative metabolism in the digestive tract. Tench were randomly distributed into five experimental groups (3 tanks per group), each of which was fed to satiety with one of the following isoproteic and isolipidic experimental diets: a control fishmeal-based diet, and four diets that included Tenebrio molitor or Hermetia illucens meal replacing 15 or 30% of fishmeal (T15, T30, H15, and H30, respectively). None of the experimental diets had a negative impact on growth or diet utilization. The meal of both insects promotes a high antioxidant capacity in the digestive tract of tench, with a decrease in lipid peroxidation with respect to the fishmeal-based diet, except in H15 group that showed values similar to controls. Little influence of insect meal on the parameters that evaluate the innate immune response of tench was observed, although an infectious challenge may be needed to highlight these effects. Although none of the insect-based diets had a negative impact on growth of tench, T. molitor seems to be a better alternative than H. illucens for tench feeding. The environmental benefits of using insect meal in tench feed would be in line with the current economic interests of the aquaculture industry, so insects represent a valid and healthy substitute of fishmeal and plant meal for fish feeding.

The first insight into black soldier fly meal in brown trout nutrition as an environmentally sustainable fish meal replacement

Insect meals are considered among the most promising feed materials in fish nutrition due to their sustainability and possibility of fish meal replacement. The present study is the first application of full-fat black soldier fly larvae (BSFL) meal in brown trout (Salmo trutta m. fario) diets. Two experiments were performed on 240 brown trout fingerlings (average body mass 4.85 g) distributed into four groups (12 tanks for the growth performance experiment, 10 fish/tank; and 12 metabolic tanks for the digestibility test, 10 fish/tank). The experimental group design was conducted as follows: control diet, with no BSFL and 35% fish meal, and experimental diets: BSFL5 – with 5% BSFL full-fat meal and 32.5% fish meal; BSFL10 – with 10% BSFL full-fat meal and 30% fish meal; and BSFL20 – with 20% BSFL full-fat meal and 25% fish meal. No effects were recorded in the case of growth performance and feed utilization parameters. The environmental sustainability of the usage of insect meals in fish diets was proven – due to the lower fish meal inclusion, the fish-in-fish-out ratio decreased by 31% in BSFL20. In the case of the viscerosomatic index, increases in BSFL5 and BSFL20 were reported. In all experimental groups, decreases in hepatosomatic index values were observed. Crude protein digestibility decreased in BSFL5 and BSFL20, while crude fat digestibility decreased only in the BSFL20 group. The effect of including BSFL full-fat meal in a brown trout diet on serum biochemical parameters was reported. The aspartate transaminase concentration increased in BSFL10 and BSFL20, while the gamma-glutamyl transpeptidase values decreased in BSFL20. In the case of total cholesterol, higher values were observed in BSFL10 and BSFL20. The albumin content decreased in the BSFL20 group, while globulin showed the highest values in the control group. The microbiota composition was not affected by insect meal inclusion. In conclusion, the results of the present study showed the high potential of BSFL full-fat meal application of up to 20% in a brown trout diet.

Tenebrio molitor larvae meal inclusion affects hepatic proteome and apoptosis and/or autophagy of three farmed fish species

Herein, the effect of dietary inclusion of insect (Tenebrio molitor) meal on hepatic pathways of apoptosis and autophagy in three farmed fish species, gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss), fed diets at 25%, 50% and 60% insect meal inclusion levels respectively, was investigated. Hepatic proteome was examined by liver protein profiles from the three fish species, obtained by two-dimensional gel electrophoresis. Although cellular stress was evident in the three teleost species following insect meal, inclusion by T. molitor, D. labrax and O. mykiss suppressed apoptosis through induction of hepatic autophagy, while in S. aurata both cellular procedures were activated. Protein abundance showed that a total of 30, 81 and 74 spots were altered significantly in seabream, European seabass and rainbow trout, respectively. Insect meal inclusion resulted in individual protein abundance changes, with less number of proteins altered in gilthead seabream compared to European seabass and rainbow trout. This is the first study demonstrating that insect meal in fish diets is causing changes in liver protein abundances. However, a species-specific response both in the above mentioned bioindicators, indicates the need to strategically manage fish meal replacement in fish diets per species.

Insect-Based Feed Ingredients for Aquaculture: A Case Study for Their Acceptance in Greece.

Simple SummarySince 2017, insects can be used as ingredients in aquafeeds in the EU. However, insect-based aquafeeds are still not broadly accepted by European aquaculture companies. Understanding the beliefs of people associated with the aquaculture sector on the use of insect-based fish diets could assist their adoption. In the present study, we ran a survey among the participants of an aquaculture conference held in Greece, in order to ask them what they think regarding the inclusion of insect meal in aquafeeds. Furthermore, we inquired nine Greek aquaculture and aquafeed companies about this issue. Greece is among the largest farmed fish producers in the EU; however, there are currently no data available on the acceptance of insect-based aquafeeds in Greece. Based on our results, the majority of the respondents were aware and in favor of the inclusion of insects in aquafeeds, mainly due to their potential to lower fishing pressure on wild fish stocks used for fishmeal production and enhance the ecological footprint and sustainability of aquaculture. Moreover, six out of nine companies were favorably disposed towards the use of insects in fish diets and four of them were willing to produce or use such diets. Further studies are warranted towards this direction.Although the inclusion of insects in fish diets is officially allowed in the EU since 2017, insect-based aquafeeds have not been widely adopted by the European aquaculture sector. In order to investigate the perceptions related with adoption trends, it is critical to explore the beliefs of people associated with the aquaculture sector on the use of insects in farmed fish diets. A survey was conducted among 228 participants of an aquaculture conference to explore their perceptions on the inclusion of insect meal in fish diets. Additionally, we investigated the attitudes of nine companies operating in the aquaculture and aquafeed sector in Greece that attended the conference towards this direction. The findings of the conference survey provide evidence that there is a wide-range awareness and acceptance regarding the use of insect-based feeds in farmed fish diets among the respondents. This is mainly driven by the expectations for the decline in fishing pressure on wild fish stocks, the reduction of the ecological footprint and the enhancement of the sustainability of the aquaculture sector. The results of the stakeholder survey show that six out of the nine companies that participated in the survey are favorably disposed towards the use of insect-based feeds. Specifically, four of them stated that they would produce or use aquafeeds based on insects. However, the results highlight the need for further research on the implementation of the wider adoption of insect-based feeds in aquaculture. The present study provides some first insights into the use of insect-based aquafeeds in Greece, for which there are no data available.

Insect meal inclusion as a novel feed ingredient in soy-based diets improves performance of rainbow trout (Oncorhynchus mykiss)

The additive effects of insect meal supplementation to diets containing a high soy protein inclusion were evaluated for growth performance, antioxidant potential and fillet nutritional quality of juvenile rainbow trout (Oncorhynchus mykiss). A basal diet (Soy) with a high-level soy protein (21% soybean meal, SBM plus 4–5.5% soy protein concentrate, SPC) was compared to similarly formulated soy-based diets supplemented with low (8%) and high levels (16%) of insect meal for diet groups Soy + IM Low and Soy + IM High, respectively. A high-level fishmeal (24%) based positive control diet (Fish meal) was also produced. All diets were iso‑nitrogenous (44%) and isolipidic (20%) and were fed to triplicate groups of rainbow trout juveniles (initial weight 32 ± 0.0 g) over the course of a 10-week trial. Fish fed the positive control diet showed significantly higher final weight, % weight gain (%WG) and specific growth rate (SGR) compared to the Soy + IM High and Soy diet groups, but these parameters were not significantly different from the Soy + IM Low diet group. The Soy and Soy + IM High diet groups showed significantly lower final weight, % WG and SGR. Feed efficiency and protein efficiency ratio was numerically higher in fish fed the Fish meal positive control diet followed by the Soy + IM Low and Soy and Soy + IM High diet groups, respectively. Among somatic indices, condition factor (CF) was significantly influenced by IM supplementation and the Soy + IM High diet group showed significantly lower CF compared to other dietary groups. Addition of insect meal significantly increased whole body amino acids viz., arginine, histidine, valine and threonine content. Insect meal supplementation significantly increased muscle α-linolenic acid content. However, α-linolenic acid content in fish fed the Soy + IM High diet was not significantly different from fish fed the Fishmeal positive control diet. Insect meal supplementation did not significantly influence EPA + DHA, total n-3 PUFA and monounsaturated fatty acid content in the muscle, whereas the significantly highest EPA/DHA and total monounsaturated fatty acids were detected in the fishmeal based positive control diet compared to other dietary treatment. The liver gene expression pattern for Δ5 desaturase was significantly higher in the Soy + IM Low diet fish, while Δ6 desaturase and fatty acid synthase (FAS) were significantly higher in Soy (basal) and Soy + IM Low diet fed fish. Elongase and fatty acid binding protein (FABP) were not significantly influenced by insect meal supplementation. Regarding the antioxidant potential, Soy diet group showed significantly higher superoxide dismutase (SOD) activity compared to insect meal included groups and positive control diet group. Glutathione peroxidase (GPX) activity was significantly reduced in Soy + IM High diet compared to other dietary groups. Finally, we conclude that insect meal inclusion at a low level (8%) is beneficial for increased growth and select fatty acid restoration for rainbow trout fed soy-based feeds.

Configuration of Gut Microbiota Structure and Potential Functionality in Two Teleosts under the Influence of Dietary Insect Meals.

Insect meals are considered promising, eco-friendly, alternative ingredients for aquafeed. Considering the dietary influence on establishment of functioning gut microbiota, the effect of the insect meal diets on the microbial ecology should be addressed. The present study assessed diet- and species-specific shifts in gut resident bacterial communities of juvenile reared Dicentrarchus labrax and Sparus aurata in response to three experimental diets with insect meals from three insects (Hermetia illucens, Tenebrio molitor, Musca domestica), using high-throughput Illumina sequencing of the V3–V4 region of the 16S rRNA gene. The dominant phyla were Firmicutes, Proteobacteria and Actinobacteria in all dietary treatments. Anaerococcus sp., Cutibacterium sp. and Pseudomonas sp. in D. labrax, and Staphylococcus sp., Hafnia sp. and Aeromonas sp. in S. aurata were the most enriched shared species, following insect-meal inclusion. Network analysis of the dietary treatments highlighted diet-induced changes in the microbial community assemblies and revealed unique and shared microbe-to-microbe interactions. PICRUSt-predicted Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly differentiated, including genes associated with metabolic pathways. The present findings strengthen the importance of diet in microbiota configuration and underline that different insects as fish feed ingredients elicit species-specific differential responses of structural and functional dynamics in gut microbial communities.