Development of Innovative Feed Products and Feed Concepts for Marine Species in Aquaculture

The sustainability challenges of the aquaculture sector will probably be closely linked with continuing interest in ingredients as alternatives to fishmeal for use within aquafeeds. Among the many protein sources available, plant proteins appear to be the most appropriate alternatives. Different aspects on the health implications of using vegetable feed ingredients on the digestive tract, plus possible effects on quality of the fish, are some of the most relevant problems currently confronting the aqua industry. The need to understand this phenomenon leads to the present thesis, in which the investigation on the feasibility of the inclusion of plant protein in aquafeed was undertaken through a multidisciplinary approach. The first study highlighted that inclusion of soybean meal in combination with different blends of plant protein maintains optimal growth in 20% fish meal dietary level for the on-growing of European sea bass. Despite fiber is considered as a component that cannot be utilized by most fish, inclusion up to 9.3% has no effects on growth, feed efficiency and digesta transit time in European sea bass. It was encouraging to note that inclusion of high levels of plant protein sources and fiber did not affect health and nutritional status of the animals. When replacing fish meal in aquafeeds, besides the research on alternative ingredients, also the nutritional profile should be considered. In the third study, it was demonstrated that taurine is a required nutrient for juvenile Southern flounder. The fourth study, highlighted that increasing the inclusion of plant ingredients, in substitution of fish meal, had no effects on quality traits of the commercial product. However, it is not yet an easy or economi¬cally feasible task to reduce the aquaculture dependence from marine feedstuff, the present thesis has contributed to provide some insights on the feasibility of the replacement of fish meal in aquafeed

Feeding common sole (Solea solea) juveniles with increasing dietary lipid levels affects growth, feed utilization and gut health

Knowledge about the nutritional requirements of common sole (Solea solea) is limited and no information regarding the optimal dietary lipid level is available yet. Thus, this study was undertaken to assess the growth response and feed utilization of common sole juveniles fed diets with increasing lipid levels. Four isonitrogenous (59% protein) pelletized diets with different dietary lipid levels (8%, 12%, 16% and 20%; L8, L12, L16 and L20, respectively) were fed to triplicate fish groups of 80 individuals to apparent satiation over 150 days. A one-way ANOVA, Tukey's post hoc test and linear regression were used to analyse the data (P 64 0.05). At the end of the trial, final body weight was significantly higher in fish fed L8 (40.7 \ub1 1.7 g), followed by those fed L12 (35.1 \ub1 1.2 g), L16 (27.9 \ub1 2.5 g) and L20 (22.1 \ub1 0.3 g). The specific growth rate was higher in fish fed L8 and L12, compared to the other treatments, and it was lowest in L20. Voluntary feed intake decreased with an increase in the dietary lipid level. The feed conversion rate, the protein efficiency ratio and the gross protein efficiency were lower in fish fed L20, while no significant differences were observed among L8, L12 and L16. Gross lipid efficiency was significantly higher in fish fed low lipid diets. Histological observations showed that 19 of 36 observed subjects had lipid droplets in the cytoplasm of enterocytes at the apex of the mucosal folds and, in some cases, also along the entire fold (intestinal steatosis). The number of fish with intestinal steatosis in groups L20 and L16 was significantly higher than the number in group L8. Ultrastructure showed large electrondense lipid droplets within the cytoplasm of enterocytes and warping of the cytoplasmic membrane (steatosis); in some cases, lipid droplets were also present within the Golgi apparatus. In conclusion, the results of this trial suggest that the diet for S. solea juveniles should include no more than 12% lipids. Higher lipid inclusions not only led to a substantial decline in performance but also affected gut health. This should be taken into consideration in formulating specific practical diets for common sole

Integrated study on production performance and quality traits of European sea bass ( Dicentrarchus labrax ) fed high plant protein diets

In the issue of fishmeal replacement, besides maintaining optimal growth, a key area of investigation for continuing to improve modern aquafeeds includes the evaluation of the effects of plant ingredients on fish quality. It is generally accepted that farmed fish quality can be influenced by the formulation of composition of their feed. Hence, the aim of the present research was to evaluate plant protein inclusion up to 84% of the overall protein content in an integrated study on growth and quality traits of European sea bass. Three diets were formulated to contain increasing plant protein levels (50, 67 and 84%; 50PP, 67PP and 84PP, respectively), with fishmeal dietary levels at 30, 20 and 10%, respectively. No significant differences due to reducing fishmeal content were observed after 118 days in terms of growth (final body weight and specific growth rate) and feed intake, even though a trend towards lower growth performance at higher fishmeal replacement levels was observed. Fish fed diet 50PP showed lower feed conversion rate in comparison to those fed diet 84PP, while no differences were recorded between diet 50PP and 67PP. No significant differences among treatments were found in protein efficiency rate. On the contrary, fish fed diet 84PP showed lower gross protein efficiency in comparison to those fed diet 50PP and 67PP. No significant differences in biometric indices and fillet composition were observed. No significant differences were found in pH, liquid holding capacity and skin colour measurements between treatments, while regarding fillet colour, significant differences were found only for H\ub0ab. In conclusion, our findings demonstrated that dietary plant proteins up to 84% of the overall protein content had no effects on quality traits of European sea bass in comparison with 50% and 67%. All experimental groups showed similar growth even though 84% plant protein inclusion negatively influenced feed and protein utilisation

Effects of dietary lipid level on growth and feed utilisation of gilthead seabream (Sparus aurata L.) reared at Mediterranean summer temperature

We investigated the effects of different dietary lipid levels on gilthead seabream, Sparus aurata, reared at Mediterranean summer temperature. Sixty fish (average weight 75 g) per tank were randomly distributed, in triplicate groups, in a recirculating rearing system (27\ub11\ub0C) and fed ad libitum five isonitrogenous (46% dietary protein) diets with increasing lipid level (16, 18, 20, 22 and 24% named D16, D18, D20, D22 and D24, respectively), over 89 days. Specific growth rate and final body weight were not affected by dietary lipid levels. Feed conversion ratio was significantly higher (P 640.05) in D16 as compared to the other treatments, most likely due to the shortage of dietary energy supply, coped with a significantly higher voluntary feed intake. Consequently, we obtained a significantly lower protein efficiency ratio and gross protein efficiency in D16. Gross lipid efficiency was significantly higher in D16 and D18 than in the other treatments. Biometric parameters and lipase activity in gut content were not influenced by dietary treatments. In conclusion, D18 seems the most suitable diet for gilthead seabream reared at Mediterranean summer temperature, providing both the lowest fish in fish out (FIFO) ratio and a protein sparing effect, which makes gilthead seabream\u2019s production economically and environmentally more sustainable

Effects of light intensity on growth, feeding activity and development in common sole (Solea solea L.) larvae in relation to sensory organ ontogeny

The effects of four light intensities (1000 lx, 500 lx, 50 lx, 3 lx) on growth, survival and feeding activity in common sole (Solea solea L.) larvae were studied from 4 to 51 days post hatching (dph). During the pelagic larval stage (4\u201312 dph), larvae reared at 3 lx showed a lower growth. From 19 onwards, the larvae reared under 3 lx displayed a significant (P 64 0.05) higher SGR than the other treatments and a higher final weight compared to 1000 lx and 500 lx. Survival rate was higher under intermediate light intensities (500 and 50 lx). Larvae reared at 3 lx displayed a significant delay in the degree of metamorphosis compared to the other treatments, while at 33 dph metamorphosis was completed under all treatments. Histological examination revealed the importance of vision and light in the first feeding of this species, while after metamorphosis, the full development of other sensory organs indicated that feeding activity is also mediated by chemosensory perception. Results indicate that high light intensity seems to be more suitable during the pelagic larvae, while the opposite would ensure better growth from the onset of metamorphosis to the benthic phas

Feeding European sea bass with increasing dietary fibre levels: Impact on growth, blood biochemistry, gut histology, gut evacuation

Changing trends in fish feed formulation, with progressively higher inclusion levels of plant ingredients, are invariably introducing more fibre despite the fact that this component cannot be utilized by most fish. The effects of increasing insoluble dietary fibre level on growth, nutrient utilisation, blood parameters and gut health in European sea bass (Dicentrarchus labrax L.) were studied over a period of 117 days. Moreover, investigation on digesta transit time through gastrointestinal evacuation pattern and digesta characteristics (moisture of digesta) were studied. Five isoproteic diets were formulated to contain increasing insoluble fibre levels, neutral detergent fibre, NDF (7.2, 8.9, 11.5, 13.1 and 15.5%) derived by the inclusion of sunflower hulls and soybean hulls. No significant differences due to fibre inclusion levels were observed in final body weight, specific growth rate, feed intake, feed conversion rate, protein and lipid efficiency. No significant differences in serum total protein, glucose, triglycerides, alkaline phosphatase and inorganic phosphorous were found. All the histological sections showed normal intestinal architecture, and inflammatory and/or degenerative changes were not present in any histological section from all subjects examined. The investigation into gastrointestinal evacuation pattern revealed no significant differences between treatments, however higher dietary fibre levels seem to increase the time required to empty the stomach while the time required to empty 90% of the hindgut content was similar in all the treatments: around 46\u201347 h. No differences were found between diets in the moisture content of digesta along the digestive tracts. We can conclude that the different insoluble fibre levels tested in this trial have no effects on overall performances and feed efficiency in European sea bass. Results from blood biochemistry profile and histology confirm good nutritional and health status of fish under all feeding treatments. The inclusion of fibre had no influence on digesta transit time. In formulation of feed for the on-growing of European sea bass insoluble fibre derived from sunflower hulls and soybean hulls can be included at a level of up to 15.5%

Farmed and wild common sole (Solea solea L.): Comparative assessment of morphometric parameters, processing yields, selected nutritional traits and sensory profile

Recent important developments in sole aquaculture have increased the availability of the farmed product on the market. The aim of this research was to characterize and compare for the first time in common sole (Solea solea) morphometric parameters, nutrients and sensory traits of cultured and wild specimens. Farmed sole, while maintaining the characteristics of a lean fish species (2% of lipid content), displayed a EPA+DHA fillet content more than twice as high as its wild counterpart. Sensory traits of \u201cpotato\u201d \u201cboiled fish\u201d sweet, firmness, astringency, chewiness, were correlated to farmed origin while whiteness, briny, \u201coctopus\u201d \u201ccrab\u201d salty, acid, bitter, umami, intensity and juiciness were linked to wild origin. Intensive farming conditions improved the nutritional value of common sole in terms of lipid content and fatty acid profile and led to sweeter sensory traits particularly associated with a terrestrial vegetable perception

Lipids and fatty acids composition of eggs in relation to larval quality from cultured common sole (Solea solea) broodstock

Eggs quality optimization is a fundamental aspect in the standardization of the production cycle of a fish species. Lipids content and fatty acids composition of common sole (Solea solea) eggs were measured and correlated to eggs and larval viability parameters along an entire reproductive season. Seventeen batches of fertile eggs obtained from natural spawning of captive breeders were characterized for lipid content (L), fatty acids content (FAs), total weight (TW), spawning temperature (T), floating rate (FR), hatching rate (HR) and survival rate of larvae (SR) at 0-6 days post hatching (dph). Based on univariate regression models it was possible to formulate significant relations using L, FAs, TW and T as independent variable. T, L, and 20:5(n-3)+20:4(n-6) (EPA+ARA), were significant (P≤0.05) correlated to FR. T, 14:0, 18:0, 22:6(n-3) (DHA), ∑monounsaturated FAs, ∑polyunsaturated FAs of the (n-3) series, and EPA+ARA were significant correlated to HR and SR. It was also found that L, 16:0, 16:1(n-7), 18:2(n-6), 20:4(n-6), saturated FAs, ∑polyunsaturated FAs of the (n-6) series had a significant effect to HR, while TW, 18:1(n-7), 20:5(n-3), ∑(n-6)/∑(n-3), DHA/EPA were significant correlated to SR. The results indicate that quantitative eggs lipids and fatty acids composition can predict eggs and larval quality of common sole. Since breeders’ diet is one of the main factors affecting eggs composition, the results of this study could provide useful information for broodstock nutrition

Molecular Characterization of Circulating Tumor DNA in Pediatric Rhabdomyosarcoma: A Feasibility Study

Rhabdomyosarcomas (RMS) are rare neoplasms affecting children and young adults. Efforts to improve patient survival have been undermined by a lack of suitable disease markers. Plasma circulating tumor DNA (ctDNA) has shown promise as a potential minimally invasive biomarker and monitoring tool in other cancers; however, it remains underexplored in RMS. We aimed to determine the feasibility of identifying and quantifying ctDNA in plasma as a marker of disease burden and/or treatment response using blood samples from RMS mouse models and patients