BackgroundTwo trials were performed to evaluate a partially defatted Hermetia illucens (HI) larvae meal as potential feed ingredient in rainbow trout (Oncorhynchus mykiss Walbaum) diets. In the first trial, 360 trout (178.9 ± 9.8 g of mean initial body weight) were randomly divided into three experimental groups (4 tanks/treatment, 30 fish/tank). The fish were fed for 78 days with isonitrogenous, isolipidic and isoenergetic diets containing increasing levels of HI, on as fed basis: 0% (HI0, control diet), 25% (HI25) and 50% (HI50) of fish meal substitution, corresponding to dietary inclusion levels of 0, 20% and 40%. In the second trial, 36 trout (4 tanks/treatment, 3 fish/tank) were used to evaluate the in vivo apparent digestibility coefficients (ADC) of the same diets used in the first trial.ResultsSurvival, growth performance, condition factor, somatic indexes, and dorsal fillet physical quality parameters were not affected by diet. The highest dietary inclusion of HI larvae meal increased dry matter and ether extract contents of trout dorsal fillet. The use of HI larvae meal induced a decrease of valuable polyunsaturated fatty acids (PUFA) even if differences were only reported at the highest level of HI inclusion. The insect meal worsened the lipids health indexes of the same muscle. Dietary inclusion of insect meal did not alter the villus height of the fish. No differences were found among treatments in relation to ADC of ether extract and gross energy, while ADC of dry matter and crude protein were higher in HI25 if compared to HI50.ConclusionsThe obtained results showed that a partially defatted HI larvae meal can be used as feed ingredient in trout diets up to 40% of inclusion level without impacting survival, growth performance, condition factor, somatic indexes, dorsal fillet physical quality parameters, and intestinal morphology of the fish. However, further investigations on specific feeding strategies and diet formulations are needed to limit the observed negative effects of the insect meal on the FA composition of dorsal muscle.

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View related articles View Crossmark data Citing articles: 4 View citing articles PAPER Partial or total replacement of soybean oil by black soldier fly larvae (Hermetia illucens L.) fat in broiler diets: effect on growth performances, feed-choice, blood traits, carcass characteristics and meat quality

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.

BackgroundThe 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.ResultsSignificant 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).ConclusionsDefatted 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.

Insects are currently being considered as a novel protein source for animal feeds, because they contain a large amount of protein. The larvae of Tenebrio molitor (TM) have been shown to be an acceptable protein source for broiler chickens in terms of growth performance, but till now, no data on histological or intestinal morphometric features have been reported. This study has had the aim of evaluating the effects of dietary TM inclusion on the performance, welfare, intestinal morphology and histological features of free-range chickens. A total of 140 medium-growing hybrid female chickens were free-range reared and randomly allotted to two dietary treatments: (i) a control group and (ii) a TM group, in which TM meal was included at 75 g/kg. Each group consisted of five pens as replicates, with 14 chicks per pen. Growth performance, haematological and serum parameters and welfare indicators were evaluated, and the animals were slaughtered at the age of 97 days. Two birds per pen (10 birds/treatment) were submitted to histological (liver, spleen, thymus, bursa of Fabricius, kidney, heart, glandular stomach and gut) and morphometric (duodenum, jejunum and ileum) investigations. The inclusion of TM did not affect the growth performance, haematological or serum parameters. The morphometric and histological features were not significantly affected either, thus suggesting no influence on nutrient metabolization, performance or animal health. Glandular stomach alterations (chronic flogosis with epithelial squamous metaplasia) were considered paraphysiological in relation to free-range farming. The observed chronic intestinal flogosis, with concomitant activation of the lymphoid tissue, was probably due to previous parasitic infections, which are very frequently detected in free-range chickens. In conclusion, the findings of this study show that yellow mealworm inclusion does not affect the welfare, productive performances or morphological features of free-range chickens, thus confirming that TM can be used safely in poultry diets.

The objective of the present study was to evaluate the effects of partial or total replacement of finisher diet soybean oil with black soldier fly (Hermethia illucens L.; HI) larva fat on the growth performance, carcass traits, blood parameters, intestinal morphology and histological features of broiler chickens. At 21 days of age, a total of 120 male broiler chickens (Ross 308) were randomly allocated to three experimental groups (five replicates and eight birds/pen). To a basal control diet (C; 68.7 g/kg as fed of soybean oil), either 50% or 100% of the soybean oil was replaced with HI larva fat (HI50 and HI100 group, respectively). Growth performance was evaluated throughout the trial. At day 48, 15 birds (three birds/pen) per group were slaughtered at a commercial abattoir. Carcass yield and proportions of carcass elements were recorded. Blood samples were taken from each slaughtered chicken for haematochemical index determination. Morphometric analyses were performed on the duodenum, jejunum and ileum. Samples of liver, spleen, thymus, bursa of fabricius, kidney and heart were submitted to histological investigations. Growth performance, carcass traits, haematochemical parameters and gut morphometric indexes were not influenced by the dietary inclusion of HI larva fat. Histopathological alterations developed in the spleen, thymus, bursa of fabricius and liver and were identified in all of the experimental groups, but HI larva fat inclusion did not significantly affect (P>0.05) the severity of the histopathological findings. The present study suggests that 50% or 100% replacement of soybean oil with HI larva fat in broiler chickens diets has no adverse effects on growth performance or blood parameters and had no beneficial effect on gut health.

This study evaluated the effects of Tenebrio molitor (TM) larvae meal inclusion in diets for broilers. A total of 160 male broiler chicks (Ross 708) at one-day of age were randomly allotted to four dietary treatments: a control (C) group and three TM groups, in which TM meal was included at 50 (TM5), 100 (TM10), and 150 (TM15) g/kg, respectively. The experimental diets were isonitrogenous and isoenergetic. Each group consisted of five pens as replicates (8 chicks/pen). After the evaluation of growth performance and haematochemical parameters, the animals were slaughtered at 53 days and carcass traits were recorded. Morphometric investigations were performed on duodenum, jejunum, and ileum and histopathological alterations were assessed for liver, spleen, thymus, bursa of Fabricius, kidney, and heart. The live weight (LW) showed a linear (12 and 25 days, P < 0.001 and P < 0.05, maximum with TM15 and TM10) and quadratic (53 days, P < 0.05, maximum with TM5) response to dietary TM meal inclusion. A linear (1 to 12 and 12 to 25 days, P < 0.001, maximum with TM15) and quadratic (12 to 25 days, P = 0.001, maximum with TM15) effect was also observed for the daily feed intake (DFI). The feed conversion ratio (FCR) showed a linear response (25 to 53 and 1 to 53 days, P = 0.001 and P < 0.05, maximum with TM15). Haematological and serum biochemical traits, carcass traits and histopathological findings were not affected by dietary TM meal inclusion (P > 0.05). TM15 birds showed lower villus height (P < 0.05), higher crypt depth (P < 0.05), and lower villus height to crypt depth ratio (P = 0.001) compared with C and TM5. In conclusion, increasing levels of dietary TM meal inclusion in male broiler chickens may improve body weight and feed intake, but negatively affect feed efficiency and intestinal morphology, thus suggesting that low levels may be more suitable. However, no effect on haematochemical parameters, carcass traits, and histological findings were observed in relation to TM meal utilization.