Review: Insects and former foodstuffs for upgrading food waste biomasses/streams to feed ingredients for farm animals

Novel Experimental Methods for the Investigation of Hermetia illucens (Diptera: Stratiomyidae) Larvae

Large-scale insect rearing for food and feed production can be improved by understanding diet digestion and host-microbe interactions. To examine these processes in black soldier fly (Hermetia illucens L.; Diptera: Stratiomyidae) larvae, two protocols were developed. Protocol 1 describes a method to produce viable, sterile black soldier fly larvae and a gentle method for diet sterilization. Sterile black soldier fly larvae can be used to study the diverse role of microbes in larval development. Nutrient requirements of sterile black soldier fly larvae are met only through diet. Viable sterile black soldier fly larvae were consistently generated using a four-step treatment with alternating immersions of eggs for 2 min each in ethanol (70%) and sodium hypochlorite (0.6%), over two cycles. A nonthermal method of diet sterilization, namely high-energy electron beam (HEEB) treatment, was introduced. Subsequently, growth of sterile black soldier fly larvae was observed on the HEEB-treated diets (40, 60, and 40% of replicates with poultry feed, liver pie, and an artificial diet, respectively) but not on autoclaved diets. In Protocol 2, we propose a novel method to collect frass from individual larvae. We then measured the metabolites in frass, using high-pressure liquid chromatography. Results on metabolites confirmed the influence of digestion. For instance, succinate increased from 1 to 2 and 7 μmol/g sample from diet to gut homogenate and frass, respectively. The collection method is a promising tool to estimate the diet and nutrient requirements of black soldier fly larvae, thus increasing the performance and reliability of black soldier fly larvae rearing. We discuss in detail the possible applications and limitations of our methods in black soldier fly larvae research.

Potentials and Challenges of Former Food Products (Food Leftover) as Alternative Feed Ingredients

Simple Summary

This review focuses on the use of ex-foods, an alternative feed ingredient in farm animal diets, composed by processed and ready-to-eat food products no longer suitable for human consumption. Such foods, which are also called former food products, are usually buried in landfill sites, despite their high potential of being used as sustainable feed ingredients. In order to obtain proper balanced diets by using these alternative feed ingredients, several aspects have to be considered. In this respect, this paper aims to address the state of the art about food leftovers used in animal nutrition in general and in pig diets specifically.

Abstract

Former food products (FFPs) are foodstuffs that, even though they are nutritious and safe, have lost their value on the human consumption market for different reasons, such as production errors leading to broken or intermediate foodstuffs, surpluses caused by logistical challenges of daily delivery, or any other reason. The nutritional features of FFPs include carbohydrates, free sugars, and possibly also fats. FFPs tend to have been processed through various technological and heat treatments that impact the nutrients and the kinetics of digestion, as well as animal response and, particularly, gastro-intestinal health. This review integrates some of the most recently published works about the chemical composition, nutritional value, digestibility and glycaemic index of ex-foods. In addition, a view on the relationship between the use of FFPs and safety issues and their effects on pigs’ intestinal microbiota are also given.

Effect of Dietary Replacement of Fishmeal by Insect Meal on Growth Performance, Blood Profiles and Economics of Growing Pigs in Kenya

Simple Summary

Pig keeping is an important source of income but the high cost of fishmeal (FM), which is the main protein source in animal feeds, has hindered the sector from realizing its full potential. As an alternative, we investigated the suitability of a meal derived from black soldier fly larvae (BSFLM) as a protein source. Pigs were fed different diet types: Control (no BSFLM: 0% (T0)), 25% (T25), 50% (T50), 75% (T75) and 100% (T100) replacement of FM by BSFLM. Average daily feed intake, body weight gain and feed conversion ratio were not affected by the replacement of FM by BSFLM. Red or white blood cell parameters did not differ among diets, except for neutrophil counts, which were higher at T75 and T100 compared to T0. At T25, T75 and T100, pigs had lower platelet counts compared to pigs fed T0 and T50. Dietary BSFLM inclusion did not influence blood cholesterol levels. The cost–benefit ratio and return on investment were similar across diets. Our study shows that BSFLM is a suitable and cost-effective alternative to FM in pig feeds.

Abstract

Pig production is one of the fastest growing livestock sectors. Development of this sector is hampered by rapidly increasing costs of fishmeal (FM), which is a common protein source in animal feeds. Here, we explored the potential of substituting FM with black soldier fly larval meal (BSFLM) on growth and blood parameters of pigs as well as economic aspects. At weaning, 40 hybrid pigs, i.e., crossbreeds of purebred Large White and Landrace were randomly assigned to five iso-nitrogenous and iso-energetic dietary treatments: Control (0% BSFLM and 100% FM (T0)), and FM replaced at 25% (T25), 50% (T50), 75% (T75) and 100% (T100) with BSFLM. Average daily feed intake (ADFI), average daily gain (ADG), body weight gain (BWG) and feed conversion ratio (FCR) were calculated for the whole trial. Hematological and serum biochemical parameters, the cost–benefit ratio (CBR) and return on investment (RoI) were evaluated. No significant effect of diet type was observed on feed intake and daily weight gain. Red or white blood cell indices did not differ among diets. Pigs fed T25, T75 and T100, had lower platelet counts compared to T0 and T50. Dietary inclusion of BSFLM did not affect blood total cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein. CBR and RoI were similar for the various diets. In conclusion, BSFLM is a suitable and cost-effective alternative to fishmeal in feed for growing pigs.

Tracing food packaging contamination: an electronic nose applied to leftover food

The use of former food products (FFPs) as alternative feed ingredients in farm animal diets has several benefits. In fact, FFPs are a way of converting losses from the food industry into ingredients for the feed industry. FFPs are produced from packaged food and in general, they are recognised as safe. Packaging materials are not accepted as a feed ingredient according to Regulation (EC) No 767/2009, which imposes a rigorous evaluation of possible residues. A sensitive and objective detection method is therefore essential for an effective risk evaluation. Six FFP samples were subjected to electronic nose analysis. Each sample was assessed under three conditions: as-received, cleaned and experimentally-spiked. Packaging remnants were also quantified using a stereomicroscope. Data were analysed via principal component analysis using SPSS software. Although the stereomicroscopy analysis showed a low content of packaging remnants in as-received samples, the electronic nose was able to differentiate between cleaned, as-received and spiked samples. However, this method was not effective when different FFPs were analysed together. In the view of the limitations of this method, it can be concluded that the electronic nose can be considered an objective and sensitive method for the detection of packaging remnants in FFPs composed of the same matrix.

Influence of Traditional vs Alternative Dietary Carbohydrates Sources on the Large Intestinal Microbiota in Post-Weaning Piglets

Simple Summary

Nutritional and environmental changes result in significant physiological changes in pigs at the weaning stage. The post-weaning period is mainly characterized by low feed intake and feed efficiency, together with intestinal disturbances. Maximizing the energy intake is known to be critical for promoting growth in weaned piglets, and it is essential to formulate diets with highly digestible and absorbable nutrients/ingredients, as the degree of intestinal maturation is limited. The current challenge is to find new sustainable, effective, and simple carbohydrate sources to satisfy these conditions without producing detrimental effects on the gut ecosystem. In this research, processed and ready-to-eat food products that are no longer suitable for humans were tested, which have high potential as an alternative energy source for pig nutrition. The results demonstrated that replacing conventional ingredients with highly digestible and simple carbohydrate-rich ingredients in the diets of post-weaning piglets did not affect their growth. However, both the abundance and composition of the bacterial community in the large intestine changed. Thus, the results should be interpreted with caution, as they are case-specific, and when these alternative feed ingredients are used in the post-weaning period, their inclusion rate and their effect on microbiota must be carefully considered.

Abstract

In this study, common cereal grains were partially replaced by former foodstuffs products (FFPs) in post-weaning piglets’ diets, to investigate how these alternative ingredients influence the faecal microbiota in the post-weaning period. Twelve post-weaning piglets were housed for 16 days in individual pens and were then fed two diets: a standard wheat-barley-corn meal diet and a diet containing 30% FFPs, thus partially substituting conventional cereals. The growth performance was monitored and faecal microbiota was characterized by the next generation sequencing of the 16S rRNA gene. The results showed no detrimental effects on growth performance when FFPs were used. However, the FFP diet decreased the bacterial richness and evenness in the large intestine, while minor differences were observed in the taxa composition. The core microbiota composition was only slightly affected, and no differences between the two groups in the gut microbiota composition at the phylum level over time were observed. Thus, although these results should be interpreted with caution, as they are case-specific, FFPs can be potentially used as alternative carbohydrate sources in post-weaning piglets, but further investigations are necessary to clarify their impact on gut health when used for a longer period.

Former Foodstuff Products in Tenebrio Molitor Rearing: Effects on Growth, Chemical Composition, Microbiological Load, and Antioxidant Status

Simple Summary

Insects represent a possible alternative nutrient source for food and feed purposes. Insects could be reared on a feed basis alternative to conventional ones of animal origin and could help to face the rising demand of proteins. Mealworm could be reared directly on former foodstuff products allowing to reduce waste materials and enhance profits in several sectors. This study demonstrates that Tenebrio molitor rearing can be done on leftovers and by-products with proficient outcomes and high-quality final products. However, rearing substrates must be carefully selected in order to maximize the outcomes in relation to the prefixed goals.

Abstract

Tenebrio molitor (mealworm) larvae represent one of the most interesting edible insects and could be reared on alternative feeds, such as former foodstuff products (FFPs). In the present work, five different FFPs (brewery spent grains, bread and cookie leftovers, and mixes of brewer’s spent grain or bread with cookies) were employed as feeding substrates. Larvae’s growth performances, chemical composition, microbial loads, and antioxidant status were determined. Chemical compositions of the substrates affected all the tested parameters. Brewery spent grains-fed larvae showed a faster growth period and higher crude protein and carbohydrate contents. The use of cookies as a single substrate or their addition to spent grains or bread increased the lipids contents, while growth was delayed. Microbial loads were partially affected by the fed diet. The antioxidant status of larvae showed different concentrations of tocopherols isoforms (δ, γ, α) in relation to the diet; however, no differences were detected in relation to the global antioxidant capacity (2,2-azinobis-(3 ethylbenzothiazoline-6-sulfonic acid), ABTS reducing activity; 1,1-diphenyl-2-pircydrazyl, DPPH radical scavenging activity; ferric reducing ability, FRAP). Results point out a high plasticity of mealworm larvae and the potential to tailor the final outcomes in relation to the substrate employed. Mealworms could be practically reared on FFPs to produce food-feed with high nutrient values.

The Effects of Diet Formulation on the Yield, Proximate Composition, and Fatty Acid Profile of the Black Soldier Fly (Hermetia illucens L.) Prepupae Intended for Animal Feed

Simple Summary

Mass rearing of the black soldier fly to be used as feed is still at an early stage. Among the different issues, larval feeding and nutrition of this species are the most relevant ones from a practical standpoint. For example, testing four different diets, we found that this insect can be efficiently reared on wheat byproducts in place of cornmeal and that using diets richer in carbohydrates or proteins can negatively affect protein accumulation, larval development, and survivorship. Accumulation of unsaturated fats in black soldier fly prepupae is a matter of great interest, and it was found to be directly dependent on the amount of these fats in the rearing substrates. By appropriately mixing different food byproducts as diet ingredients, our research suggests that black soldier fly prepupae meal suitable for the feed formulation can be obtained.

Abstract

The black soldier fly (BSF; Hermetia illucens L.) is a very promising insect species due to the ability to convert low-value substrates in highly nutrient feed. This work aimed to study the effect of three nominally isoenergetic diets containing plant ingredients such as barley, alfalfa, and wheat byproducts, formulated to be higher in nonfiber carbohydrates (TMD1), fibers (TMD2), and protein (TMD3) in comparison to an extensively genetic modified cereal (cornmeal)-based diet (C), on the growth, yield, and nutritive traits of BSF prepupae (BSFPs). Three growing trials with four biological replicates were carried out. Proximate and fatty acid analyses were performed on the diets and BSFPs. Feed conversion ratios (FCR), dry matter and nutrient yields, and apparent concentration factors (aBCF) for fatty acids (FAs) were calculated. Diet formulation had a substantial effect on the survival, development rate, and larval yield, but the FCR was unaffected. The BSFPs fed TMD3 did not result in a higher crude protein content in comparison to the C or TMD2 diets. Despite the leveled fat content of the diets, BSFPs reared on TMD1 were highest in fat, saturated FA, and fat yield. An apparent bioconcentration factor (aBCF) value lower than unity that was found for the unsaturated FA suggests that the BSFPs inefficiently absorb them from the diet or possibly turn them into saturated FA. However, the unsaturated FA accumulation in BSFPs depended on the levels that were found in the diet, which suggested some possibilities for the FA profile modulation. Overall, the TMD2 performed well despite the low-value of its main ingredients and high fiber content and can be considered to be a feasible option for the mass rearing of BSFPs that are intended for animal feed.