The study aimed to determine the apparent total tract digestibility coefficients (ATTDC) of nutrients, the apparent metabolizable energy (AME and AMEn) and the amino acid (AA) apparent ileal digestibility coefficients (AIDC) of a partially defatted (BSFp) and a highly defatted (BSFh) black soldier fly larvae meal. The experimental diets were: a basal diet and two diets prepared by substituting 250 g/kg (w/w) of the basal diet with BSFp or BSFh, respectively. Significant differences were found between BSFp and BSFh meals for ATTDC of the nutrients: BSFp resulted more digestible than BSFh, except for ATTDC of CP which did not differed between meals, while a statistical trend was observed for ATTDC of DM and EE. The AME and AMEn values were significantly (P < 0.05) different between the two BSF meals, with higher levels for BSFp (16.25 and 14.87 MJ/kg DM, respectively). The AIDC of the AA in BSFp ranged from 0.44 to 0.92, while in BSFh they ranged from 0.45 to 0.99. No significant differences were observed for the AA digestibility (0.77 and 0.80 for BSFp and BSFh, respectively), except for glutamic acid, proline and serine that were more digestible in the BSFh meal (P < 0.05). Defatted BSF meals can be considered as an excellent source of AME and digestible AA for broilers with a better efficient nutrient digestion. These considerations suggested the effective utilization of defatted BSF larvae meal in poultry feed formulation.

The present study has evaluated the effects of different inclusion levels of a partially defatted black soldier fly (Hermetia illucens L.; HI) larva meal on the growth performance, blood parameters and gut morphology of broiler chickens. A total of 256 male broiler chickens (Ross 308) were reared from d 1 to d 35 and assigned to 4 dietary treatments (8 replicates/treatment and 8 birds/replicate). HI larva meal was included at increasing levels (0, 5%, 10% and 15%; HI0, HI5, HI10 and HI15, respectively) in isonitrogenous and isoenergetic diets formulated for 3 feeding phases: starter (1–10 d), growing (10–24 d) and finisher (24–35 d). Two birds per pen were slaughtered at d 35 and morphometric investigations and histopathological alterations were performed. The live weight (LW) showed linear and quadratic responses to increasing HI larva meal (maximum for HI10 group). Average daily gain (ADG) showed a linear and quadratic responses to HI meal (maximum for HI10 group) during starter and growing periods. A linear decrease was observed for ADG during the finisher period. The daily feed intake (DFI) showed a linear and quadratic effect during the starter period (maximum for HI10 group). Linear and quadratic responses were observed for the feed conversion ratio (FCR) in the growing period and for the whole period of the experiment. The FCR showed a linear response in the finisher period (maximum for HI15). No significant effects were observed for the blood and serum parameters, except for the phosphorus concentration, which showed linear and quadratic responses as well as glutathione peroxidase (GPx) activity, the latter of which showed a linear response. The HI15 birds showed a lower villus height, a higher crypt depth and a lower villus height-to-crypt depth ratio than the other groups. Increasing levels of dietary HI meal inclusion in male broiler chickens may improve the LW and DFI during the starter period, but may also negatively affect the FCR and gut morphology, thus suggesting that low levels may be more suitable. However, no significant effects on the haematochemical parameters or histological findings were observed in relation to HI meal utilization.

This paper reviews current knowledge on two feedstuffs, that is, insect meal and fish by-products, as alternatives to conventional animal protein sources. After an introductory part that highlights the need for sustainable development of animal production, the alternative protein sources are discussed. In particular, after providing some indications on their production and supply focussing on EU, a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis was performed to identify the key factors that could help or impair the development of both protein sources production sectors. Finally, future perspectives are presented. The use of processed animal proteins derived from insects in farmed fish feeding is recognised by the EU legislation that authorises the use of proteins from seven insect species and the allowed substrates to rear insects. Insects have several advantages in nutritional value and the amino acid composition of their proteins generally meet animal requirements for good growth and health. The SWOT analysis indicated that insect meals can be considered as feed functional ingredients with beneficial properties that depend on the insect species, rearing system adopted, and the substrate used for their growth. Insects are expected to be increasingly used as a replacement for conventional animal-derived proteins, especially in aquafeeds. In the section regarding fishery and aquaculture by-products, the potential use of raw materials obtained during seafood processing is discussed. Peptides and amino acids recovered from as hydrolysed proteins can be used in animal feeds to partially substitute conventional protein feedstuffs thus providing nutrients, bioactive compounds and feed additives for animals. The SWOT analysis identified opportunities and weaknesses. Both the alternative protein sources are promising alternative feed ingredients for livestock production.

In 2018, the industrial compound feed production throughout the world was 1.103 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.

This study evaluated the effects of diets containing Tenebrio molitor (TM) larvae meal on growth performances, somatic indexes, nutrient digestibility, dorsal muscle proximate and fatty acid (FA) compositions of rainbow trout. Three hundred sixty fish were randomly divided into three groups with four replicates each. The groups were fed diets differing in TM inclusion: 0% (TM0), 25% (TM25) and 50% (TM50) as fed weight basis. Weight gain was not affected by treatment. Feeding rate was significantly higher in TM0 than TM50. Feed conversion ratio was significantly higher in TM0 than TM25 and TM50, while an opposite trend was observed for protein efficiency ratio and specific growth rate. The survival rate was significantly lower in TM0 than TM25 and TM50. The apparent digestibility of protein was significantly lower in the TM50 group than the other groups, while the apparent digestibility of dry matter, organic matter and lipids was unaffected by treatment. If compared to control, the protein and lipid contents of fillets were respectively increased and decreased following TM inclusion in the diet. The Σn3/Σn6 FA ratio of fish dorsal muscle was linearly (TM0>TM25>TM50) reduced by TM inclusion in the diet. Results suggested that TM could be used during the growing phase in trout farming; however, additional studies on specific feeding strategies and diet formulations are needed to limit its negative effects on the lipid fraction of fillets