Isoenergetic-practical and semi-purified diets for protein requirement determination in Hermetia illucens larvae: consequences on life history traits

BACKGROUND: Black soldier fly (BSF) is one of the most promising species for the intensive breeding of insects given its adaptability and its efficiency in the conversion of waste. To maximize the production and use waste as substrates, it is essential to determine the larvae nutritional requirements. The study aims to evaluate the effects of 5 practical, semi-purified and isoenergetic diets (PSPID) with increasing protein levels (10%, CP10; 14%, CP14; 16%, CP16; 19%, CP19) on BSF life history traits. A total of 2000 six-day-old larvae were weighed and divided into groups of 100 (4 replicates/treatment [PSPID and Gainesville diet (GA) used as environmental control]). In larva-prepupa stage, sampling was carried out on 30 individuals/replicate, while in prepupa-adult stage on 35. RESULTS: In the whole larval stage, the CP16 treatment performed better when compared to the other groups. At 18 days old, the CP14 treatment showed a higher weight than the CP19 (P < 0.01), while the CP10 and CP16 weights were intermediate. On the contrary, the CP10 prepupae weight was higher than the CP19 (P < 0.01). The CP10 and CP14 pupae performed better in terms of weight when compared to the others (P < 0.01). The dietary treatments did not affect the adult parameters. The sex significantly influenced both the exuvia weight, which was the greatest in females (P < 0.001), and the fly lifespan, longest in males (P < 0.05). Fly lifespan was also influenced by the interaction between treatment and sex, with the CP19 females showing a longer life than the others (P < 0.05). CONCLUSIONS: In conclusion, the optimal protein level considering the whole larval stage is 16% on dry matter (DM). At 18 days old, looking at the size intended for the meal production, it can be considered 14% on DM. The result obtained on adult emergence in PSPID may not be attributable to the protein content. Further researches on macronutrients requirements determination have to be conducted to evaluate the substrates composition effects on BSF life history traits

Determination of lipid requirements in black soldier fly through semi-purified diets

The insect market is still far from an effective upscale and, to achieve this goal, it is necessary to know the BSF dietary requirements for the production maximization. Worldwide, given the waste variability, is not always easy to identify the optimal waste-based mixture that can allow to reach the best production, in terms of quantity and quality. Due this reason, nutritional need ranges are the basic knowledge, affordable for everyone, to increase the profitability of the insect farming. The study aims to evaluate the effects of 6 semi-purified, isonitrogenous and isoenergetic diets (SPII) with increasing lipid levels (1%, L1; 1.5%, L1.5; 2.5%, L2.5; 3.5% L3.5; 4.5%, L4.5) on BSF life history traits (6 replicates/treatment and 100 larvae/replicate). The Gainesville diet was used as environmental control. Considering the whole larval stage, 4.5% lipid level guarantees better performance when compared to content lower than 2.5%. The L4.5 10-day-old larvae yielded greater when compared to the other dietary treatments. At 14 and 18 days of age, the larvae of the groups above 2.5% performed better than L1, while the L1.5 showed intermediate results. Lipid levels below 1.5% on DM, when compared to 4.5%, resulted in a smaller prepupa and pupa size. The results obtained on the adult stage do not allow the identification of a lipid levels ideal range, as in the larval stage. In conclusion, in the whole larval stage and in prepupae/pupae phases, lipid percentage lower than (or equal to) 1% have a negative effect on growth. Other research will be needed in order to evaluate lipid levels above 4.5% on DM

Effects of compost-bedded pack barn on circulating cortisol and beta-endorphins in dairy cows: A case study

SIMPLE SUMMARY: Management and housing conditions have been reported to significantly affect the health and welfare of livestock species. Therefore, the adoption of novel, alternative housing systems (such as the compost-bedded pack barn, developed in the USA) requires extensive research to assess the implications for animal welfare. From a general point of view, animal welfare is typically assessed by means of animal-based (such as blood biochemical markers) and resource-based (such as management practices) indicators. Based on such considerations, the present study evaluated the fluctuation of circulating cortisol and beta-endorphins in dairy cows housed in a conventional freestall barn (FB) and in the alternative compost-bedded pack barn (CB). The results obtained suggest that the CB housing system did not elicit significant changes in either blood cortisol or beta-endorphins. ABSTRACT: The up-to-date literature suggests that the compost-bedded pack barn housing system is capable of remarkably improving productive and reproductive performance, as well as health status and welfare, in dairy cattle. However, there is currently limited knowledge available on the endocrine and biochemical changes in animals housed in such alternative systems. Therefore, this study aimed to measure blood cortisol (COR) and beta-endorphins (BE) in 22 two-year-old primiparae Fleckvieh cows, who were randomly allotted to the following two different housing systems: CB (n = 11) and FB (n = 11). Blood samples were collected at the beginning of the experiment (T0) and every two months thereafter (T1, T2, and T3). The COR and BE were measured through an immunoenzymatic kit. With the only exception being T0, no differences were observed over time between the two groups, neither for COR nor for BE. However, the blood cortisol levels of the CB cows decreased over time, while a T1 peak was identified in the FB group. On the contrary, both the housing systems displayed numerically higher BE at T3 than at the other experimental times. Therefore, the overall data suggest that the compost-bedded pack barn did not significantly affect the studied parameters. Accordingly, cow welfare should be assessed using a wider panel of animal-based indicators

Effect of dietary supplementation with insect fats on growth performance, digestive efficiency and health of rabbits

Background: The present work aimed at evaluating the effect of the dietary replacement of soybean oil (S) by two types of insect fats extracted from black soldier fly larvae (H, Hermetia illucens L.) and yellow mealworm larvae (T, Tenebrio molitor L.) on growth performance, nutrient digestibility, blood parameters, intestinal morphology and health of growing rabbits. Methods: At weaning, 200 crossbred rabbits (36 days old) were allotted to five dietary treatments (40 rabbits/group): a control diet (C) containing 1.5% of soybean oil and four experimental diets where soybean oil was partially (50%) or totally (100%) substituted by H (H50 and H100) or T (T50 and T100) fats. Total tract digestibility was evaluated on 12 rabbits per treatment. The growth trial lasted 41 d and, at slaughtering (78 days old), blood samples were collected from 15 rabbits per treatment, morphometric analyses were performed on duodenum, jejunum and ileum mucosa, and samples of liver, spleen and kidney were submitted to histological evaluation. Results: No difference was observed between the control and the experimental groups fed insect fats in terms of performance, morbidity, mortality and blood variables. The addition of H and T fats did not influence apparent digestibility coefficients of dry matter, protein, ether extract, fibre fractions and gross energy. Gut morphometric indices and organ histopathology were not affected by dietary inclusion of H and T fats. Conclusions: H and T fats are suitable sources of lipid in rabbit diets to replace soybean oil without any detrimental effect on growth performance, apparent digestibility, gut mucosa traits and health

Evaluation of carcass and meat traits of Muscovy duck fed with black soldier fly partially defatted meal

The aim of this study was to evaluate the carcass characteristics and breast meat quality in Muscovy duck (Cairina moschata domestica) fed different inclusion levels of a partially defatted black soldier fly larva (BSF) meal. A total of 256 Muscovy ducklings (average live weight, LW: 71.32\ub12.70 g) were reared from day 3 to day 48 and randomly allotted in 32 pens (8 replicates/treatment). Four different diets were formulated with increasing substitution level of corn gluten meal with BSF larva meal (0, 3, 6 and 9%; BSF0, BSF3, BSF6 and BSF9, respectively) and divided in 3 feeding phases: starter (1-14 days), grower (14-35 days) and finisher (35-48 days). At day 48, 2 animals/replicate were slaughtered and dissected to determine their carcass yields. The weights of spleen, bursa of Fabricius, liver, heart and abdominal fat were recorded. Breast and thigh muscles were then excised from 16 ducks/treatment and weighted. Ultimate pH (pHu) and L*, a*, b* colour values were then measured on breast muscle. The collected data were tested by means of oneway ANOVA evaluating the effect of dietary BSF inclusion level by polynomial contrasts. Significance was declared at P<0.05. The inclusion of BSF did not affect final LW (2,515.68\ub192.42 g on average). Hot and cold carcass weights showed a quadratic response (P<0.05) to increasing BSF larva meal, with a minimum corresponding to BSF6; however, refrigeration losses were not affected by treatments. Weight of spleen, bursa of Fabricius, liver and heart did not differ among treatments. The weight of abdominal fat showed a quadratic response to increasing BSF meal with a minimum corresponding to BSF6 group (P<0.05). Breast and thigh yields, pHu and L*, a*, b* colour values did not differ among groups. With the exception of BSF6, the inclusion of BSF meal did not affect meat traits and carcass characteristics, confirming the potential use of BSF meal in Muscovy duck diets

Effects of Tenebrio molitor larvae meal inclusion in rainbow trout feed: myogenesis-related gene expression and histomorphological features

The effects of Tenebrio molitor larvae meal (TM) dietary inclusion in rainbow trout diet were evaluated on muscular growth using gene expression and histomorphological features of liver, spleen, kidney, anterior and posterior gut through histopathological analyses. Two hundred fifty-two grow-out rainbow trout were fed four experimental diets containing increasing levels of TM: 0% (TM0), 5% (TM25), 10% (TM50), and 20% (TM100) corresponding to different levels of fish meal replacement (0, 25, 50, and 100%, respectively). Muscular growth was evaluated analysing the expression of various genes involved in different steps of myogenesis. Among the analysed genes, only MyoD expression resulted significantly higher in fish fed TM100 compared to fish fed TM0. The gut histomorphology was not affected by TM dietary inclusion and villus height differs from anterior and posterior segments regardless of the fed diet. Histopathological alterations were observed in all the sampled organs for all the dietary treatments; however, dietary TM inclusion did not influence either development or severity of the observed histopathological changes. The results obtained confirmed the safe utilisation of TM as an alternative protein source in rainbow trout diets and highlighted the necessity to deepen the studies of TM effect on the myogenesis process, especially at a molecular level.Highlights Rainbow trout can effectively be fed with a TM protein source. Total FM substitution by TM (TM100) decreased MyoD gene expression. Increasing TM dietary inclusion did not influence gut histomorphology