Fatty acid profile of lipids and caeca volatile fatty acid production of broilers fed a full fat meal from Tenebrio molitor larvae

Effect of dietary supplementation with algae extracts on growth performance and caecal microbiota of broiler chickens

1. The objective of this study was to test the dose response of dietary supplementation with algae extracts rich in marine-sulphated polysaccharides (MSP1 and MSP2) on the growing performance, body composition at slaughter and caecal microbiota of broiler chickens.2. Male broiler Ross 308 chicks 1-d-old were distributed into eight groups, a control group (unsupplemented), four groups supplemented with increasing doses of algae extract MSP1 (40, 81, 121 and 162 g/ton feed) and three groups supplemented with increasing doses of algae extract MSP2 (40, 81 and 162 g/ton feed). Each group comprised six pens of 56 chickens.3. All chickens were reared under challenging conditions, i.e. high rearing density of 42 kg/m2, fed growing and finishing diets containing, palm oil, rye and high levels of wheat and subjected to short daily fasting periods. The growth performance was recorded during rearing. At 10, 22 and 31 d of age, 12 chickens per group were euthanised to collect the caecal contents and determine microbiota composition and short-chain fatty acid levels. At d 35, the quality of litter and the condition of feathers, footpads and tarsals were scored. At d 36, 7 chickens per pen were slaughtered under commercial conditions to determine carcass composition and breast meat quality (ultimate pH and colour).4. Algal extract MSP1 increased the weight of the caeca and butyrate concentration in the caeca at d 22 (p ≤ 0.05). It increased the ultimate pH of breast fillet measured after slaughter at d 36 (p ≤ 0.05). Moreover, the group receiving 162 g/t MSP1 had a more diverse microbiota at d22. However, algal extract MSP2 had negligible effect on the different measured parameters.

Substitution of soybean meal for yellow mealworm meal in the diet of slow-growing chickens provides comparable carcass traits and meat quality

1. This study investigated the effects of incorporating yellow mealworm (Tenebrio molitor) larval meal as a partial and/or complete substitute for soybean meal on carcass and meat quality in slow-growing chickens.2. A total of 256 one-day-old male broilers were randomly allocated to 1 of 32 experimental units distributed among four treatments (n = 8): the control treatment (C), where soybean (SB) meal was the protein source, and three experimental treatments, in which SB meal was replaced by Tenebrio molitor (TM) larval meal at levels of 50% (T1), 75% (T2) and 100% (T3), respectively. Three different feed phases (1-29; 29-57 and 57-92 d of age) were used for each treatment. All chickens were slaughtered at 92 d of age, with eight animals per treatment randomly selected to assess carcass and meat quality. Near-infrared reflectance spectroscopy (NIR) was used to classify meat quality.3. Carcass traits were not significantly different between treatments, except for head and thigh weight, which were higher in the control group (p < 0.01). In terms of physicochemical characteristics, treatment T2 showed less yellowness (p < 0.05), while water and cooking losses were lower in treatments T1 and T2 (p < 0.01). Meat from both T1 and T2 groups had lower shear forces (p < 0.01), higher moisture content (p < 0.01) and less protein (p < 0.05) compared to treatments C andT3. Birds fed T3 had the highest meat ash content (p < 0.01). Chickens consuming TM had higher monounsaturated fatty acid (MUFA) levels and lower polyunsaturated fatty acid (PUFA) and n-6 acidsPUFA (p < 0.01).4. Substitution of SB with TM is a protein alternative for slow-growing chickens that supports carcass and meat quality comparable to those fed a conventional diet.

Carcass traits and meat quality assessment of two slow-growing chicks strains fed Acheta domesticus larval meal

Presently, there has been a noticeable rise in the consumption of poultry meat within the general population, particularly focusing on poultry sourced from alternative rearing systems as opposed to intensive ones. This study evaluated the impact of incorporating house cricket (Acheta domesticus,AD) larvae meal into the diet of 2 slow-growing chicken strains on their carcass traits and meat quality. A total of 256 one-day-old male chicks were utilized, with 128 belonging to the Red (R) strain and 128 to the Naked Neck (NN) strain. Chicks from each strain were randomly assigned to 16 replicates of 8 chicks each. Eight replicates were allocated to 2 distinct treatments (n=64 chicks/treatment) based on the diet employed: the control treatments for the Red (R-C) and Naked Neck (NN-C) strains were fed soybean meal, while the other 2 treatments were fed AD meal (R-AD and NN-AD). Three different rations were used throughout the growth cycle of the animals, tailored to meet the nutritional needs of the birds. All chickens were slaughtered at 95 d of age, and eight chickens per treatment were randomly chosen to assess carcass traits and meat quality. Near-infrared reflectance spectroscopy (NIRS) was employed to classify meat based on the feed and the chick strain, achieving a correct discrimination of 100% of the samples. The carcass traits exhibited significant alterations due to the inclusion of insect larval meal in the diet, resulting in reduced values across all parameters for chickens consuming AD meal, irrespective of genotype. The pH and cooking losses were generally higher for chicks fed cricket meal, as occurred with moisture. However, protein content was lower in the meat of chicks consuming cricket meal. Fat content showed lower values for NN chickens. There were minimal differences in the fatty acid profile, with lower C18:3n-3 values for chickens fed cricket meal. Therefore, including Acheta domesticus meal in the diets of slow-growing chick strains is a viable alternative to replace soybean meal. It provides meat quality characteristics comparable to those obtained in conventional systems.

A Systematic Review and Metanalysis on the Use of Hermetia illucens and Tenebrio molitor in Diets for Poultry

Insect meal as a protein source has been considered a sustainable way to feed animals. H. illucens and T. molitor larvae meal are considered high-protein sources for poultry, also presenting considerable amounts of fatty acids, vitamins, and minerals. However, other potential components in insect meal and insect oil have been more extensively studied in recent years. Chitin, lauric acid, and antimicrobial peptides can present antimicrobial and prebiotic functions, indicating that low levels of their inclusion in insect meal can beneficially affect broilers' health and immune responses. This systematic review was developed to study the impact of insect products on the health parameters of broilers, and a metanalysis was conducted to evaluate the effects on performance. A database was obtained based on a selection of manuscripts from January 2016 to January 2023, following the mentioned parameters. Both H. illucens and T. molitor meal or oil products had positive effects on poultry health status, especially on the ileal and cecal microbiota population, immune responses, and antimicrobial properties. The average daily gain was greater in broilers fed T. molitor meal compared to H. illucens meal (p = 0.002). The results suggest that low levels of insect meal are suitable for broilers, without resulting in negative effects on body weight gain and the feed conversion ratio, while the insect oil can totally replace soybean oil without negative impacts.

Effects of Yellow Mealworm (Tenebrio molitor) on Growth Performance, Hepatic Health and Digestibility in Juvenile Largemouth Bass (Micropterus salmoides)

This study investigated the effects of yellow mealworm meal (TM) on growth performance, hepatic health and digestibility in juvenile largemouth bass (Micropterus salmoides). The fish were fed with the basic feed and the test feed (70% basic feed and 30% raw materials) containing Cr₂O₃, and feces were collected for digestibility determination. The fish were fed with five isonitrogenous (47% crude protein) and isolipidic (13% crude lipid) diets, in which fishmeal (FM) was replaced with 0% (TM0), 12% (TM12), 24% (TM24), 36% (TM36) and 48% (TM48) TM. The fish were reared in cylindrical plastic tanks in a recirculating aquaculture system for 11 weeks. The apparent digestibility coefficients (ADC), of dry matter, crude protein and crude lipid, in largemouth bass of TM were 74.66%, 91.03% and 90.91%, respectively. The ADC of total amino acid (TAA) of TM in largemouth bass was 92.89%, and the ADC of essential amino acid (EAA) in TM in largemouth bass was 93.86%. The final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) in the TM24 group were significantly higher than those in other groups. Similarly, the highest mRNA expression levels of hepatic protein metabolism genes (pi3k, mtor, 4ebp2 and got) and antioxidant enzyme (glutathione peroxidase, Gpx; catalase, Cat) activities were observed in the TM24 group. Moreover, the expression levels of anti-inflammatory factors (il-10 and tgf) in liver were up-regulated and the expression levels of pro-inflammatory factors (il-8 and il-1β) in liver were down-regulated. Quadratic regression model analysis, based on weight gain rate (WGR) against dietary TM level, indicated that the optimum level of dietary TM replacing FM in largemouth bass diet was 19.52%. Appropriate replacement levels (less than 36%) of FM by TM in the diets can enhance the antioxidant capacity and immunity of largemouth bass. However, high levels of FM substitution with TM (more than 48%) in the feeds can damage the liver health and inhibit the growth of largemouth bass. Notably, largemouth bass has high ADC and high utilization of TM, which indicates that it is feasible to use TM as feed protein source for largemouth bass.

A review of black soldier fly (Hermetia illucens) as a potential alternative protein source in broiler diets

Since per capita global meat utilization is predicted to increase to 40% from 2019 to 2050, global use of cultivable land in livestock, poultry, and feed production is 30%. Use of alternative protein sources as animal feed can be a solution to minimize cropland usage in conventional feed production. Commonly used protein sources in animal diets like soybean meal and fish meal are facing challenges of high demand, but the current production might not fulfill their dire need. To overcome this issue, the discovery of alternative protein sources is the need of the hour, insect meals like black soldier fly (BSF) are one of these alternative protein sources. These flies are non-infectious, bite-less, can convert the variant types of organic waste (food wastes, animal and human excreta) proficiently into rich profile biomass with reduced harmful bacteria count and do not serve as a vector in disease transmission. Based on the substrate used, the BSF larvae protein, fat and ash contents vary from 37-63%, 7-39% and 9-28% on dry matter basis, respectively. Previous studies have reported that using BSF and its byproducts as alternative protein sources in broiler diets with partial or complete replacement of conventional protein sources. In this review, a brief introduction to insect meal, BSF origin, life cycle, nutritional profile, influences on growth performance, carcass characteristics, fatty acid profile of meat, biochemical properties of blood, gut morphology and microbiota of the caecum along with its influence on laying performance of layers has been discussed in detail. Studies have concluded the partial replacement of conventional protein sources with BSF is possible, whereas complete replacement may cause poor performance due to reduced digestibility up to 62% attributable to chitin content (9.6%). Further studies to corroborate the effect of dietary BSF on growth performance, carcass characteristics, fatty acid profile of meat, and gut morphology and caecum microbiota are required to standardize the inclusion levels in feeds for higher performance of poultry.

Effects of Fly Maggot Protein Replacement of Fish Meal on Growth Performance, Immune Level, Antioxidant Level, and Fecal Flora of Blue Foxes at Weaning Stage

Simple Summary

Given the shortage of fish meal, other animal protein replacements are actively being researched. One such alternative is fly maggot protein—a highly nutritious insect protein containing chitin, lysozyme, and other biologically active substances. The purpose of this study was to examine how the replacement of fish meal with fly maggot protein affects growth, immune indexes, antioxidant levels, and fecal microflora in blue foxes (Alopex lagopus) during weaning. The results showed that fly maggot protein replacement had no adverse effects on the growth, immune indexes, and antioxidant levels of blue foxes at weaning. Further, it could modulate the fecal microflora. This indicates that fly maggot protein can serve as a novel animal protein alternative to fish meal for feeding blue foxes.

Abstract

Dietary protein is a key nutritional parameter and warrants special attention in animal husbandry. This study aimed to evaluate the effect of replacing fish meal (F) with fly maggot protein (M) on the growth performance, antioxidant levels, immune indexes, and fecal microflora in weaned blue foxes (Alopex lagopus). Twenty weaned blue foxes were randomly assigned to the control (F diet; 6% of F) or experimental (M diet; F substituted by M) group (10 blue foxes per group). The duration of the trial was 28 days. The results showed that there was no significant difference in average daily gain between group M and group F during the experiment (p = 0.473). Moreover, the diarrhea index was similar between group M and group F during the entire experimental period (p = 0.112). At the end of the experiment, the levels of IL-6 and IgG in group M at 28 d were significantly higher than that in group F (p = 0.004, p = 0.025, respectively), but not IL-1β, IL-2, SIgA, IgM, and TNF-α. The levels of SOD in group M at 28 d were significantly higher than those in group F (p = 0.001), and no difference of MDA and T-AOC was found between group F and M (p = 0.073, p = 0.196, respectively). In both groups, the diversity of fecal microbes first increased and then decreased with the progress of the experimental period. Initially, there were differences in the composition of microbial communities between the two groups. However, this difference was attenuated at later stages of the experimental period. In conclusion, fly maggot protein can replace fish meal as a source of animal protein in feed material for blue foxes during the weaning period.

Insect meal as a feed ingredient for poultry

Shortage of protein feed resources is the major challenge to the world farm animal industry. Insects are known as an alternative protein source for poultry. A wide range of insects are available for use in poultry diets. Insect larvae thrive in manure, and organic waste, and produce antimicrobial peptides to protect themselves from microbial infections, and additionally these peptides might also be functional in poultry feed. The feed containing antimicrobial peptides can improve the growth performance, nutrient digestibility, intestinal health, and immune function in poultry. Insect meal contains a higher amount of essential amino acids compared to conventional feedstuffs. Black soldier fly, mealworm, housefly, cricket/Grasshopper/Locust (Orthoptera), silkworm, and earthworm are the commonly used insect meals in broiler and laying hen diets. This paper summarizes the nutrient profiles of the insect meals and reviews their efficacy when included in poultry diets. Due to the differences in insect meal products, and breeds of poultry, inconsistent results were noticed among studies. The main challenge for proper utilization, and the promising prospect of insect meal in poultry diet are also addressed in the paper. To fully exploit insect meal as an alternative protein resource, and exert their functional effects, modes of action need to be understood. With the emergence of more accurate and reliable studies, insect meals will undoubtedly play more important role in poultry feed industry.

Effect of trimmed asparagus by-products supplementation in broiler diets on performance, nutrients digestibility, gut ecology, and functional meat production

Background and Aim

Trimmed asparagus by-products (TABP) is the resultant waste from asparagus possessing. TABP has fructans, such as inulins and fructooligosaccharide, which can be utilized as an alternative prebiotic. This study was conducted to examine the effect of TABP dietary supplementation on the productive performance, nutrient digestibility, gut microbiota, volatile fatty acid (VFA) content, small-intestine histology, and meat quality of broilers.

Materials and Methods

A total of 320 1-day-old broiler chicks (Ross 308®) were raised under ambient temperature and assigned through a completely randomized design to one of four dietary treatments, with four replicates per treatment. The dietary treatments comprised corn-soybean basal diet supplemented with 0 (control), 10, 30, or 50 g/kg TABP. All birds were provided drinking water and feed ad libitum to meet the standard nutritional requirements of National Research Council for broiler chickens.

Results

TABP supplementation to the broilers significantly increased the apparent ether extract, crude fiber, and gross energy digestibility (p<0.05). TABP supplementation significantly increased lactic bacteria and Enterococcus spp. numbers as well as acetic, propionic, butyric, and total VFA levels (p<0.01); on the other hand, it also significantly decreased Salmonella spp. and Escherichia coli contents in the cecum compared with the control group (p<0.01). Moreover, TABP supplementation increased villus height in the duodenum and jejunum (p<0.01), cryptal depth in the jejunum and ileum (p<0.01), and villus surface areas in the duodenum, jejunum, and ileum (p<0.01). Overall, 0-35 day TABP supplementation significantly increased the feed intake (p<0.01) and average daily gain of broilers (p<0.05), but not significantly affected the viability, productive index, and economic benefit return (p>0.05). The carcass characteristics, pH, color, and water holding capacity of the chicken meat between groups were not significantly different (p>0.05). All levels of TABP supplementation appeared to be a feasible means of producing broilers with the lower serum low-density lipoprotein cholesterol and triglyceride levels as well as atherogenic indices of serum compared with the control (p<0.05). Cholesterol contents and palmitic acid, oleic acid, saturated fatty acids, and Monounsaturated fatty acids levels decreased with an increase of TABP supplementation (p<0.05). Furthermore, TABP supplementation decreased atherogenic index (AI) and thrombogenicity index (TI) of meat (p<0.05).

Conclusion

Supplementation of 30 g/kg TABP in broiler diet could enhance broiler performance and provide chicken meat with beneficial properties, with decreased AI and TI resulted from altered cholesterol and fatty acid profiles.

Performance indicators and gastrointestinal response of rabbits to dietary soybean meal replacement with silkworm pupae and mealworm larvae meals

The objective of this study was to determine the effects of silkworm pupae meal (SPM) and mealworm larvae meal (MLM) on the production results and function of the digestive system in rabbits. Thirty male New Zealand White growing rabbits were divided into three feeding groups: control (C) (10% soybean meal [SBM] in the diet), group SPM (5% SBM and 4% SPM) and group MLM (5% SBM and 4% MLM). Compared with group C, rabbits of groups SPM and MLM, were characterised by higher final body weight and daily body weight gains. They were also found to have better apparent total tract digestibility (ATTD) of ether extract, and acid detergent fibre (ADF) and acid detergent lignin (ADL). Increased digesta viscosity was observed in these rabbits, as well as reduced extracellular activity of bacterial α-glucosidase, β-glucosidase, α-arabinofuranosidase and β-xylosidase in the caecal digesta. Similar differences between groups were also noted for the intracellular activity of β-glucuronidase, total activity of β-xylosidase and α-glucosidase. The SPM and MLM treatments contributed to an increase in the extracellular and total activity of N-acetyl-β-D-glucosaminidase (NAGase) in the caecal digesta. The SPM and MLM treatments were characterised by increased extracellular/total activity of colonic bacterial NAGase as well as increased release rates of NAGase and β-cellobiosidase, compared with group C. The rabbits fed the MLM diet had the lowest caecal concentrations of acetic acid, propionic acid, and total short chain fatty acids (SCFA). The proportion of butyric acid in the caecal SCFA profile was significantly lower in group MLM than in group C. The SPM treatment reduced the colonic concentration of iso-valeric acid. Group C had the highest colonic SCFA pool. It can be concluded that an inclusion of 4% SPM and 4% MLM in rabbit diets improved their production results, as well as beneficially increased the ATTD of fat, ADF and ADL without compromising the ATTD of other nutrients and energy. Although both dietary insect-derived products caused a mobilisation of microbiota to utilise of chitin (see NAGase activity), they stifled the metabolism of large intestinal microbiota, as manifested by decreased enzyme activity and lower SCFA concentrations.

Effects of Dietary Inclusion Level of Microwave-Dried and Press-Defatted Black Soldier Fly (Hermetia illucens) Larvae Meal on Carcass Traits and Meat Quality in Broilers

Limited information is available regarding the use of microwave-dried Hermetia illucens larvae meal (HILM) as a dietary protein source for broiler diets. Therefore, we investigated the effects of microwave-dried HILM on carcass traits, meat quality, fatty acid (FA) profiles of abdominal fat and meat, and heavy metal residues of the meat in broilers. A total of 126 male broilers were randomly assigned to three dietary treatment groups (6 replicates and 7 birds/pen): a control diet and two experimental diets in which soybean meal was replaced with 25 or 50% HILM. The broilers were slaughtered at 35 days; the carcasses were weighed, and breast and leg meats were excised from 12 birds per treatment (2 birds/pen) for meat analysis. The breast meat quality and proximate composition showed satisfactory results. For the higher HILM diet, the content of saturated FA in the abdominal fat was increased and that of polyunsaturated FA was decreased (p < 0.001); the FA profile of leg meat did not significantly differ between groups. The concentrations of undesirable heavy metals in the HILM and leg meat were below permissible levels. However, the carcass weight was decreased (p < 0.001) in the 50% HILM group. Microwave-dried HILM is a potential ingredient for broiler diets, with up to 25% substitution showing no detrimental effects on carcass traits, meat quality, FA profiles, and heavy metal residues in the meat.

Evaluation of the Production Performance and the Meat Quality of Chickens Reared in Organic System. As Affected by the Inclusion of Calliphora sp. in the Diet

The use of insects can be a possible source of protein. This study uses Calliphora sp. larvae (CLM) as a protein source in 320 one-day-old medium-growing male chicks (RedBro) during their first month of life. Chickens were randomly assigned to four dietary treatments. Each group consisted of 10 animals, and a total of 8 replicas. Control group was fed with a certified organic feed. The experimental treatments were supplemented with 5% (T2), 10% (T3), or 15% (T4) of CLM, reducing in each case the corresponding percentage of feed quantity. Productive development and meat quality were analyzed, and near infrared spectroscopy (NIRS) was used as a tool for classifying the samples. Chickens of T4 showed greater final body weight and total average daily gain, but they reduced consumption and feed conversion ratio (FCR). The chicken breast meat of T4 had lower cooking losses and higher palmitoleic acid content (p < 0.01). NIRS classified correct 92.4% of samples according to the food received. CLM is presented as a potential ingredient for the diet of medium-slow growing chickens raised in organic systems.

Tenebrio molitor and Zophobas morio Full-Fat Meals in Broiler Chicken Diets: Effects on Nutrients Digestibility, Digestive Enzyme Activities, and Cecal Microbiome

This study was conducted to investigate the effect of insect full-fat meals added in relatively small amounts to a complete diet on the coefficients of apparent ileal digestibility, short-chain fatty acid (SCFA) concentrations, bacterial enzymes, and the microbiota community in the cecal digesta of broiler chickens. In total, 600 one-day-old female Ross 308 broiler chicks were randomly assigned to six dietary treatments with 10 replicate pens/treatment and 10 birds/pen. The groups consisted of a negative control (NC) with no additives; a positive control (PC; salinomycin 60 ppm), and supplementation with 0.2% or 0.3% Tenebrio molitor or Zophobas morio full-fat meals. Z. morio (0.2%) addition increased the activities of α- and β-glucosidase and α-galactosidase. Dietary insects significantly decreased the cecal counts of the Bacteroides-Prevotella cluster in comparison to those in the NC and PC. Whereas, Clostridium perfringens counts were increased in the broiler chickens subjected to the 0.3% Z. morio treatment. In conclusion, small amounts of full-fat insect meals added to broiler diets were capable of reducing the abundance of potentially pathogenic bacteria, such as the Bacteroides-Prevotella cluster and Clostridium perfringens. In addition, this supplementation was able to stimulate the GIT microbiome to produce enzymes, especially glycolytic enzymes.

Animals Fed Insect-Based Diets: State-of-the-Art on Digestibility, Performance and Product Quality

In 2018, the industrial compound feed production throughout the world was 1103 metric billion tons, which was an increase of 3% compared to 2017. In order to meet the needs of the increasing population, a further increment in compound feed production is necessary. Conventional protein sources are no longer suitable to completely satisfy the increment of feed production in a sustainable way. Insects are one of the most promising options, due to their valuable nutritional features. This paper reviews the state-of-the-art of research on the use of insect meals and oils in aquatic, avian and other animal species diets, focusing mainly on the effects on digestibility, performance and product quality. In general, insect-derived product digestibility is affected by the insect species, the inclusion levels and by the process. Sometimes, the presence of chitin can lead to a decrease in nutrient digestibility. The same considerations are true for animal performance. As far as product quality is concerned, a dramatic effect of insect products has been recorded for the fatty acid profile, with a decrease in valuable n3 fatty acids. Sensory analyses have reported no or slight differences. Insect-derived products seem to be a good alternative to conventional feed sources and can make an important contribution to the sustainable development of the livestock industry.

Intestinal Morphometry, Enzymatic and Microbial Activity in Laying Hens Fed Different Levels of a Hermetia illucens Larvae Meal and Toxic Elements Content of the Insect Meal and Diets

Simple Summary

Recently, several studies have focused on the use of insect larvae meal as an alternative to soybean meal in poultry diets. In this regard, it is crucial to understand all the possible aspects related to the chemical-nutritional characteristics, the effects on the animals’ health and welfare, and the safety of different insect meals. This study aimed to evaluate volatile fatty acids production in the caeca, the intestinal morphometry, and the brush border enzymatic activity of hens fed different levels of Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) larvae meal for 24 weeks. The research also aimed to contribute to the knowledge of the concentration of toxic elements in insect meals. Overall, the insect meal inclusion affected the small intestine morphometry, the enzymatic activity, and the caecal microbial activity. The soybean meal group showed the highest intestinal functionality, while a compensatory mechanism, probably mediated by the chitin, led to a positive increase of volatile fatty acids and butyrate in the 50% protein replacement diet with potential positive effects on gut healthiness. The levels of toxic elements in the diets and insect meal were lower than the maximum levels of heavy metals set by the EU Commission for the feed.

Abstract

To evaluate the effects of feeding a Hermetia illucens (HI) larvae meal on the different intestinal traits of hens, and to determine the toxic elements’ concentration in the insect meal and diets, 162 hens were randomly allotted to three groups. The control received a corn-soybean meal-based diet (SBM); the HI25 and HI50 groups received two diets in which the 25% and 50% of the dietary protein were replaced by the HI protein, respectively. The duodenal and jejunal villi height and villi/crypt were higher (p < 0.01) in the SBM than in the HI groups. The ileal villi height was higher (p < 0.05) in the SBM and HI25 groups than the HI50. The HI50 group exhibited a lower duodenal maltase activity. The intestinal alkaline phosphatase (IAP) activity linearly decreased in the duodenum and jejunum as the dietary insect meal inclusion increased. The HI50 group had a higher acetate and butyrate level than the SBM. The levels of cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) in the diets and insect meal were lower than the maximum values established by the EU Commission. The 25% soybean protein replacement with Hermetia illucens larvae meal in the diet of laying hens was more suitable and closer to the optimal level than 50%.