The effects of the particle size of four different feeds on the larval growth of Tenebrio molitor (Coleoptera: Tenebrionidae)

Diet is one of the most important factors affecting the growth and lifecycle of Tenebrio molitor L. The chemical and nutritional properties of the diet of mealworms are well studied whereas its physical properties are almost neglected. This work aims to study the effects of four different particle sizes (0–0.8, 0.8–2, 2–3 and 3–4 mm) of four different feeds (wheat bran, chicken feed pellets, grounded corn kernels and alfalfa dried pellets). Four-week-old larvae were reared on the experimental substrates for four to six weeks depending on the feed. Our results indicate that particle size can signifi cantly infl uence larval growth and that particles smaller than 2 mm improve larval growth on all feeds except alfalfa pellets. The maximum larval weight was slightly different for wheat bran (12%) when comparing particle sizes smaller than 2 mm with greater than 2 mm but increased up to 70% when corn kernels were used as feed. Signifi cant differences were found between the different feeds for growth rate, larval weight and variability in larval weight. The larvae that reached an average weight of 100 mg the fastest were those reared on wheat bran followed by chicken feed and corn kernels. Larvae reared on alfalfa pellets did not reach an average weight of 60 mg. The variability in larval growth was lowest when fed wheat bran followed by chicken feed and alfalfa pellets, and the highest variability was recorded when fed corn kernels. In conclusion, both the type (wheat bran, chicken feed and corn kernels) and particle size (< 2 mm) of the feed were important determinants of larval growt

Effects of four herbs on the composition and growth performance of Tenebrio molitor larvae

Tenebrio molitor (MWs) are able to convert grain byproducts into high-quality biomass, which can be processed into animal feed. Since several herbs are sometimes added in small quantities to some baking materials, this study examines the effects of the dietary inclusion of herbs on growth performance, nutrient composition and the antioxidant activity of MWs. The MWs were reared on a control diet consisting of wheat bran alone, as well as a wheat bran supplemented with four different herbs: basil, oregano, rosemary and thyme. The herbs were added in two concentrations, 0.125% and 2% on a dry matter basis (DM). All experiments were conducted in the dark at 27 °C with 60% relative humidity for five weeks. Growth performance parameters were recorded throughout the trial. Nutritional composition and antioxidant activity were analysed in the resulting larvae. A greater inclusion of herbs resulted in lower levels of protein content. Only the inclusion of oregano led to a lower fat content compared to the control group. Minor detrimental effects on larval chemical composition were observed, which could be attributed to the higher total polyphenolic content (TPC) of the herbs that appeared to have had a negative impact on the larval TPC. A negative correlation was observed between the TPC of the substrates and the larval TPC. In contrast, the larval antioxidant activity was enhanced by both types of herbs and their inclusion level. Concluding, dietary incorporation of herbs had no or minor effect on growth performances and nutritional profile in T. molitor

Amino acid requirements of yellow mealworm and black soldier fly larvae

In order to achieve optimal growth and health of farm animals, a different amount/ratio of essential amino acids in the feed is necessary in each phase of life. Knowledge about which amino acids are essential and in which quantities/proportions they are best administered has already greatly advanced the pig and poultry sector and is still being generated today. For the still young, rapidly developing insect sector, this knowledge could mean a major step forward towards breeding optimization. Therefore, in this research the needs of the 2 most commercially reared insect species, namely mealworms (Tenebrio molitor) (MW) and black soldier fly larvae (Hermetia illucens) (BSF), were investigated. The focus was on requirements for lysine, methionine, threonine, phenylalanine and tryptophan based on evidence from the literature and those of pigs. Semi-artificial diets based on at least 25% wheat bran (MW) and chicken feed/water (30/70) (BSF) (basic feed important for structure and certain micronutrients) supplemented with sugar and synthetic amino acids were tested. The diets were isoenergetic and isoproteinous. Of the amino acids studied, one was administered in different doses per experiment. The non-essential glutamic acid was used as a substitute at lower doses. Growth, as measured by weight gain, and survival were observed. The following results were for MW and BSF respectively. For lysine from a content of 0.35 g/100 g diet and 0.53 g/100 g diet no extra growth was noticeable. For methionine this was from 0.13 g/100 g and 0.16 g/100 g. Each time more threonine was given, a significant difference could be noticed and the minimum doses were around 0.42 g/100 g and 0.49 g/100 g. With tryptophan, for MW, there were no differences between the different concentrations. At the lowest dose of 0.06 g/100 g the maximum growth was already reached, whereas for BSF this was at 0.13 g/100 g

Inclusion of Hermetia Illucens larvae or prepupae in an experimental extruded feed: process optimisation and impact on in vitro digestibility

This study investigated the effect of extrusion on digestibility of different blends containing Hermetia illucens (HI) larvae or prepupae. Five blends of HI larvae or prepupae and wheat flour, in a ratio of 25:75, with or without sunflower oil addition, have been formulated as follows: prepupae\u2009+\u2009wheat (no oil); prepupae\u2009+\u2009wheat (low oil); prepupae\u2009+\u2009wheat (medium oil); prepupae\u2009+\u2009wheat (high oil); larvae\u2009+\u2009wheat (no oil). Ether extract (EE) content in different blend was 31.5, 38.9, 46.3, 53.7 and 46.27\u2009g\u2009kg 121 on wet basis (wb), respectively. Blends were homogeneous for moisture (238.9\u2009g\u2009kg 121) and crude protein (112.6\u2009g\u2009kg 121 wb). Feed blends were extruded by a co-rotating, conical twin-screw mini extruder and net torque value (NTV) was recorded as indicator of extrudability. The best performing blend was furtherly tested at four barrel temperatures (60, 70, 80 and 90\u2009\ub0C). In vitro organic matter digestibility (OMD) and in vitro crude protein digestibility (CPD) were measured to evaluate the effect of extrusion process on nutritional value. Increasing the blend EE content up to 53.74\u2009g kg 121 wb, NTV was reduced by four times (<100 Ncm) compared to 31.5 and 38.9\u2009g kg 121 wb EE blends. The best performing mixture was larvae\u2009+\u2009wheat (no oil). Extrusion process increased OMD but not CPD compared to unextruded control, while different extrusion temperature did not affect OMD nor CPD. Concluding, extrusion can contribute to increase OMD in insect containing feed blends. EE content in the blends is a key variable that should be defined in the process

A survey of the mycobiota associated with larvae of the black soldier fly (Hermetia illucens) reared for feed production

Feed security, feed quality and issues surrounding the safety of raw materials are always of interest to all livestock farmers, feed manufacturers and competent authorities. These concerns are even more important when alternative feed ingredients, new product developments and innovative feeding trends, like insect-meals, are considered. The black soldier fly (Hermetia illucens) is considered a good candidate to be used as feed ingredient for aquaculture and other farm animals, mainly as an alternative protein source. Data on transfer of contaminants from different substrates to the insects, as well as the possible occurrence of toxin-producing fungi in the gut of non-processed insects are very limited. Accordingly, we investigated the impact of the substrate/diet on the intestinal mycobiota of H. illucens larvae using culture-dependent approaches (microbiological analyses, molecular identification through the typing of isolates and the sequencing of the 26S rRNA D1/D2 domain) and amplicon-based next-generation sequencing (454 pyrosequencing). We fed five groups of H. illucens larvae at the third growing stage on two substrates: chicken feed and/or vegetable waste, provided at different timings. The obtained results indicated that Pichia was the most abundant genus associated with the larvae fed on vegetable waste, whereas Trichosporon, Rhodotorula and Geotrichum were the most abundant genera in the larvae fed on chicken feed only. Differences in the fungal communities were highlighted, suggesting that the type of substrate selects diverse yeast and mold genera, in particular vegetable waste is associated with a greater diversity of fungal species compared to chicken feed only. A further confirmation of the significant influence of diet on the mycobiota is the fact that no operational taxonomic unit common to all groups of larvae was detected. Finally, the killer phenotype of isolated yeasts was tested, showing the inhibitory activity of just one species against sensitive strains, out of the 11 tested species

The basics of edible insect rearing. Handbook for the production chain

Looking for a handbook on how to design and upscale edible insect rearing? This easy to read handbook describes the basic knowledge and a detailed step-by-step plan for rearing edible insects. The book presents information essential for further development of the entire insect chain and contains many practical recommendations for the start/setup of professional insect rearing. The reader is first submerged into the fascinating world of edible insects such as black soldier fly, housefly, mealworm, cricket, and locust. A concise overview is provided to get more familiar with the biology and physiology of edible insects. Based on this basic knowledge the book focuses on design principles for large scale insect production, facility design, engineering, insect production management, management of unwanted organisms, economics, and aspects related to the legal framework. The chief editor, co-editors and lead authors of the chapters are from Belgium, Denmark and The Netherlands. These countries have a tradition of professional insect rearing. Reading this handbook will contribute to a successful entrepreneurship in edible insect rearing. This handbook also contains very interesting teaching materials for secondary, higher, and university education

Review: Recent advances in insect-based feeds: from animal farming to the acceptance of consumers and stakeholders

The search for new, alternative and sustainable feeding sources, including insects, has become an important challenge on the feed market. In 2017, the European Union (EU) started to allow the use of insect meals as feeds for fish. In addition, in 2021, the EU also authorised the use of insect meal for pig and poultry farming. However, the adoption of insect meal by the European aquaculture sector is still limited, and this is mostly due to the lack of availability of insects and their higher costs than conventional feed ingredients. Thus, the insect-based feed industry is still in its infancy, and its successful development and integration in the food value chain depend on several factors. Among these, the technical feasibility and production of quality products, and acceptance by European consumers and farmers are relevant factors. To address these points, this narrative review describes the state of the art of the potential role of insect-based feeds. The stakeholders' and consumers' perspectives are investigated, along with the effects of insect-based feeds on the production and nutritional values of fish, poultry (meat and eggs), and pork. Indeed, matching the nutritional values of insect products with conventional feeds is one of the future challenges of the insect sector, as their nutritional composition is highly dependent on the rearing substrates, and thus, their use in animal feeding needs to be investigated carefully. Feeding animals with insect-based diets affects their growth performances and the chemical composition of the derived products (fish fillets, meat, and eggs). Whether these effects can be considered positive or negative seems to depend to a great extent on the percentage of insects included in their diets and the chemical composition of the ingredients. The use of insect-based feeds has also shown a potential to improve the nutritional features and values of animal products and even to add new ones. Finally, many of the acceptance studies on the use of insects in feeds have focused mostly on the consumers' perception rather than on industry stakeholders (e.g., farmers). Future research should focus more on the farmers' perceptions on and market analyses of these innovative feeds. Even though it is likely that the upscaling of the insect sector will lead to a decrease in prices and an increase in market availability, it is still critical to understand the potential barriers and drivers for the implementation of insects as feeds from a production point of view. (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)