1H-NMR-Based Metabolic Profiling in Muscle and Liver Tissue of Juvenile Turbot (Scophthalmus maximus) Fed with Plant and Animal Protein Sources

Circular economy driven feed ingredients and emerging protein sources, such as insects and microbial meals, has the potential to partially replace fishmeal in diets of high-trophic fish. Even though growth and feed performance are often unaffected at low inclusion levels, the metabolic effects are unknown. This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). A 1H-nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. The comparative approach revealed a decrease in metabolites that are associated with energy deficiency in both tissues of fish fed with fishmeal-reduced diets compared to the commercial-like diet (CTRL). Since growth and feeding performance were unaffected, the observed metabolic response suggests that the balanced feed formulations, especially at lower fishmeal replacement levels, have the potential for industry application

Sustainable fish feeds: potential of emerging protein sources in diets for juvenile turbot (Scophthalmus maximus) in RAS

In Europe, turbot aquaculture has a high potential for sustainable production, but the low tolerance to fishmeal replacement in the diet represents a big issue. Therefore, this study investigated the effects of more sustainable feed formulations on growth and feed performance, as well as nutritional status of juvenile turbot in recirculating aquaculture systems. In a 16-week feeding trial with 20 g juvenile turbot, one control diet containing traditional fishmeal, fish oil and soy products and two experimental diets where 20% of the fishmeal was replaced either with processed animal proteins (PAP) or with terrestrial plant proteins (PLANT) were tested. Irrespective of diets, growth performance was similar between groups, whereas the feed performance was significantly reduced in fish of the PAP group compared to the control. Comparing growth, feed utilisation and biochemical parameters, the results indicate that the fish fed on PAP diet had the lowest performance. Fish fed the PLANT diet had similar feed utilisation compared to the control, whereas parameters of the nutritional status, such as condition factor, hepato-somatic index and glycogen content showed reduced levels after 16 weeks. These effects in biochemical parameters are within the physiological range and therefore not the cause of negative performance. Since growth was unaffected, the lower feed performance of fish that were fed the PAP formulation might be balanced by the cost efficient formulation in comparison to the commercial and the PLANT formulations. Present study highlights the suitability of alternative food formulation for farmed fish

Effects of alternative feed ingredients on the growth of Dicentrarchus labrax and the circadian rhythm of Scophthalmus maximus in recirculating aquaculture systems linked to consumer perception of seafood in Europe

In dieser Dissertation werden Empfehlungen zur Steigerung des nachhaltigen Verbrauchs und der Produktion in der europäischen Aquakultur gegeben. Die Forschung basiert auf einem transdisziplinären Ansatz, der europäische Verbraucherperspektiven mit neuen Futterkonzepten für den Europäischen Wolfsbarsch (Dicentrarchus labrax) und der Erkennung des zirkadianen Rhythmus beim Steinbutt (Scophthalmus maximus) kombiniert, um das Wohlergehen der Tiere zu verbessern und potenzielle neue Managementstrategien für Aquakulturbetriebe zu entwickeln. Die Aquakultur ist nach wie vor der am schnellsten wachsende Sektor der Lebensmittelproduktion weltweit, und es werden nachhaltige Systeme benötigt, um die Ernährungssicherheit zu gewährleisten und die Ziele für nachhaltige Entwicklung (SDGs) zu erreichen. Eine vielversprechende und weit verbreitete Lösung für die Zukunft der intensiven Fischzucht ist die Kombination aus Kreislaufwirtschaft und rezirkulierenden Aquakultursystemen (RAS). Dieser Ansatz könnte die Produktivität erhöhen und die Umweltbelastung und den Ressourcenverbrauch verringern, was zu einer verbesserten Wahrnehmung durch die Verbraucher führt. Das ist wichtig, da die Verbraucher die treibende Kraft hinter dem Konsum von Meeresfrüchten sind, und ihr Kaufverhalten das Erscheinungsbild nachhaltiger Fischprodukte im Supermarkt beeinflusst. Das Verständnis der Verbraucherperspektive ist daher der erste Schritt zu einer nachhaltigeren Produktion. Die Ergebnisse meiner Doktorarbeit deuten darauf hin, dass die wichtigsten Faktoren für die Verbraucher, beim Kauf nachhaltiger Aquakulturprodukte, die Herkunft der Fische (einschließlich ihrer Hältungssysteme), die Nachhaltigkeit und das Wohlergehen der Tiere sind. Leider wird die Zucht von Fischen in intensiven Aquakulturen von der Öffentlichkeit nach wie vor negativ beurteilt, da es in den letzten Jahrzehnten viele schwerwiegende ökologische Probleme gegeben hat, wie z. B. den Missbrauch von Antibiotika. Die größten Bedenken beziehen sich allerdings auf den Anteil von Wildfängen im Aquakulturfutter und das Wohlergehen der Zuchttiere. Die Entwicklung alternativer Futtermittel und die Verbesserung des Wohlergehens der Fische haben daher das Potenzial, die Wahrnehmung der Verbraucher in Richtung einer positiveren Einstellung zu verändern und somit das Kaufpotential zu steigern. Durch die Entwicklung neuer Strategien könnten intensive diesen Bedenken entgegenwirken. Produktbeschreibungen und Öko-Labels könnten so zur Sensibilisierung der Verbraucher beitragen und in Verbindung mit einer Lebenszyklusanalyse (LCA) oder auch Ökobilianz ergänzt werden. Diese könnte den Kohlenstoff-Fußabdruck sowie den Energie- und Wasserverbrauch miteinbeziehen und für mehr Transparenz für den Konsumenten sorgen. Meine Ergebnisse deuten darauf hin, dass eine informationsbasierte Strategie, die sich auf die Herkunft des Produktes sowie seine Nachhaltigkeit konzentriert, ein wirksames Instrument sein könnte, um das Bewusstsein der Verbraucher zu ändern als auch die Fischzüchter zu ermutigen, in nachhaltige Futtermittel und Zuchttechniken zu investieren. Ökobilianzen haben gezeigt, dass nicht nachhaltig produzierte Fischfuttermittel intensive Aquakulturbetriebe, wie z. B. RAS, stark negativ beeinträchtigen. Futtermittel für karnivore Fische enthalten oft einen hohen Anteil an Fischmehl und Fischöl, die oft als nicht nachhaltige Ressourcen angesehen werden. Aus diesem Grund befasst sich der zweite Teil meiner Doktorarbeit mit alternativen Futterkonzepten für Wolfsbarsch, um die Nachhaltigkeit zu verbessern und gleichzeitig das Fischwachstum, die Rentabilität der Zuchtbetriebe und das Wohlergehen der Tiere zu gewährleisten. Der Europäische Wolfsbarsch ist die wichtigste Aquakulturart im Mittelmeer und steht nach dem Lachs an zweiter Stelle des höchsten Pro-Kopf-Verbrauchs in der Europäischen Union. Meine Arbeit zeigt, dass Hydrolysate und Nebenprodukte aus der Aquakultur sowie pflanzliche und tierische Proteine Fischmehl aus marinen Fischbeständen ersetzen können, ohne dass dies negative Auswirkungen auf das Wachstum, die Futterverwertung, die sensorischen Eigenschaften, die Ernährungskomponenten oder das Wohlergehen der Fische hat. Dies zeigt, dass die Futtermittel des europäischen Wolfsbarsches durch die Anwendung einer Kreislaufwirtschaft und die Verwendung von pflanzlichen und tierischen Proteinen nachhaltiger werden kann. Im letzten Teil meiner Doktorarbeit habe ich das Wohlergehen von Fischen eingehender untersucht. Fische und alle anderen Lebewesen verfügen über einen zirkadianen Rhythmus (CR), der alle Stoffwechselprozesse steuert. Dieser CR ist artspezifisch, und meines Wissens liegen für Steinbutt noch keine Daten vor. Der Steinbutt ist eine sehr wertvolle Art in der europäischen Aquakultur, und das Verständnis seiner Tag- und Nachtrhythmen ist notwendig, um sein Wohlergehen und damit sein Wachstum in intensiven Aquakulturbetrieben zu verbessern. Meine Ergebnisse deuten auf Stoffwechselspitzen bei Aminosäuren und Zuckern um 15 Uhr hin, die zur Optimierung von Fütterungsregimen und Zuchtpraktiken genutzt werden könnten. Insbesondere können Tätigkeiten im Betrieb, wie Fütterung (welcher Verdauungsstress auslösen kann) oder Transport, den Stress erhöhen und sollten während der Spitzenwerte von Stress Metaboliten vermieden werden. Die Nutzung von Schwankungen des natürlichen Stoffwechsels in Kombination mit Kreislaufwirtschaft und optimierten Fütterungskonzepten könnte dazu beitragen, das Wohlergehen und das Wachstum der Tiere nachhaltig zu verbessern. Diese Arbeit vermittelt ein umfassendes Bild der Auswirkungen der verschiedenen interdisziplinären Ansätze in der europäischen Aquakultur, vom Verbraucher bis zum einzelnen Fisch. Die Verwendung nachhaltiger und regionaler Futterstoffe in der Ernährung karnivorer Fische kann nicht nur die Abhängigkeit von Rohstoffen verringern, sondern auch die Kaufbereitschaft der Verbraucher gegenüber der Aquakultur positiv beeinflussen. Durch den Einsatz von spezies-spezifischen Fütterungs- und Handhabungszeiten könnte das Wohlergehen der Fische verbessert werden ohne dem Farmer zusätzliche Kosten aufzubürgen. Somit liefert meine Arbeit Ideen für neue Aquakultur Praktiken, die sowohl die Rentabilität der Zuchtbetriebe als auch die Wahrnehmung der Verbraucher verbessern können

Water parameters and nutrient concentrations during the feeding experiment of juvenile turbot (Scophthalmus maximus) fed with emerging protein sources

This study examined the growth response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). The feeding experiment was carried out from April to July 2019 in the Centre for Aquaculture Research (ZAF) at the Alfred Wegener Institute for Polar and Marine research in Bremerhaven, Germany. The juvenile turbot (Scophthalmus maximus) were purchased from France Turbot (L'Épine, France) and acclimated to the recirculating aquaculture system (RAS) for 2 weeks prior to starting the 16 weeks experimental trial. The condition of the process water was monitored constantly with a SC 1000 Multiparameter Universal Controller (Hach Lange GmbH, Germany), and the nutrient concentration was measured with the QuAAtro39 AutoAnalyzer (SEAL Analytical, Germany) twice a week

Body length and body weight of juvenile turbot (Scophthalmus maximus) fed with emerging protein sources

This study examined the growth response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal (FM) replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). The feeding experiment was carried out from April 2019 to July 2019 in the Centre for Aquaculture Research (ZAF) at the Alfred Wegener Institute for Polar and Marine research in Bremerhaven, Germany. The juvenile turbot (Scophthalmus maximus) were purchased from France Turbot (L'Épine, France) and acclimated to the recirculating aquaculture system (RAS) for 2 weeks prior to starting the 16 weeks experimental trial. To elucidate the effects of the protein sources and the level of FM replacement on the growth performance, in this study, a diet with a balanced mixture and higher level of FM replacement was included. Fish were weighed to 0.2 g precision and measured in length to 0.5 cm precision every 4 weeks

Chemical analysis of diets, carcass and faeces of juvenile turbot (Scophthalmus maximus) fed with emerging protein sources

This study examined the growth response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal (FM) replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). The feeding experiment was carried out from April to July 2019 in the Centre for Aquaculture Research (ZAF) at the Alfred Wegener Institute for Polar and Marine research in Bremerhaven, Germany. The juvenile turbot (Scophthalmus maximus) were purchased from France Turbot (L'Épine, France) and acclimated to the recirculating aquaculture system (RAS) for 2 weeks prior to starting the 16 weeks experimental trial. To elucidate the effects of the protein sources and the level of FM replacement on the proximate and mineral composition of the carcass and the apparent digestibility of the diets, in this study. The chemical analysis of the diets was conducted in duplicates and of the carcass and faeces as pooled replicates per tank (n =5 tanks per diet). The carcass samples were minced frozen using a meat grinder (MADO Primus, Germany), refrozen at−20 °C and then freeze-dried for 48 h. The samples of the experimental diets and faeces were freeze-dried for 24 h. The experimental diets and whole body samples were further homogenised in a knife grinder (5000 rpm, 30 s, Grindomix GM 200, Retsch, Germany). The moisture content, ash, crude protein, crude lipid and energy of the experimental diets, carcass and faeces was determined after AOAC (1980). Moisture content of the feeds was determined by drying the samples at 105 °C for 24 h. The moisture content of the whole body and faeces was determined by freeze-drying. Total ash content was determined by combustion of the samples in a muffle oven at 550 °C for 6 h. The total nitrogen in the feed and whole body samples was determined following the automated Kjeldahl Method. Due to small sample volume in the faeces samples, the total nitrogen was determined after the Dumas method. For all samples, the measured total nitrogen was converted to equivalent crude protein (%) by the numerical factor of 6.25. Crude lipid was determined by acid hydrolysis. Gross energy was measured in an adiabatic bomb calorimeter (Model 6100; Parr Instrument, Germany). For the analysis of the mineral content, 0.2 g of freeze-dried and homogenised samples of the experimental diets, whole body and faeces was digested in 3 mL nitric acid (HNO3) (65%, trace grade) in a microwave oven (CEM MARS5, Germany) according to DIN EN 13,805 (2014). After digestion, the samples were diluted with Milli-Q water to 50 mL. Calcium, potassium, magnesium, phosphorus, arsenic, copper, iron, manganese, yttrium and zinc concentrations were analysed in an ICP-OES (iCAP7400; Fisher Scientific, Germany). As reference fish muscle (ERM – BB422, EU) was used

Feed intake of juvenile turbot (Scophthalmus maximus) fed with emerging protein sources

This study examined the growth response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal (FM) replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). The feeding experiment was carried out from April 2019 to July 2019 in the Centre for Aquaculture Research (ZAF) at the Alfred Wegener Institute for Polar and Marine research in Bremerhaven, Germany. The juvenile turbot (Scophthalmus maximus) were purchased from France Turbot (L'Épine, France) and acclimated to the recirculating aquaculture system (RAS) for 2 weeks prior to starting the 16 weeks experimental trial. To elucidate the effects of the protein sources and the level of FM replacement on the feed performance, in this study, a diet with a balanced mixture and higher level of FM replacement was included. The fish were fed twice a day (9 am and 2 pm) ad libitum. After the fish were fed in the afternoon (30 min later), the remaining pellets were netted (mesh size 1 mm) from the tanks, dried for 24 h at 50 -°C and weighed. To account for potential weight loss of the non-eaten pellets, duplicates of each experimental diet (2 g each) were incubated at 16 -°C and 100 cycles per minute in 100 mL water which was taken from the experimental recirculation system (30 °% salinity) (Obaldo et al. 2002)

Effects of dietary plant and animal protein sources and replacement levels on growth and feed performance and nutritional status of market-sized turbot (Scophthalmus maximus) in RAS

One part of aquaculture sustainability is reducing the environmental footprint of aquaculture feeds. For European aquaculture, this means finding feed ingredients that are produced within the economic community, and that are not in conflict with human consumption. This is especially challenging when formulating diets for carnivorous fish such as turbot with low tolerance to fishmeal replacement that are both nutritious and economically and environmentally sustainable. Therefore, we investigated the effects of two novel and innovative feed formulation concepts on growth and feed performance and the nutritional status of market-sized turbot in a recirculating aquaculture system. In a 16-week feeding trial, 440 turbot (300 ± 9 g) were fed twice a day with a control diet (CTRL), based on a commercial formulation, and four experimental diets. The experimental diets were designed to investigate the effects of two formulations concepts based on sustainable terrestrial plant proteins (NoPAP) or processed animal proteins (PAP) and of 30% and 60% fishmeal replacement with emerging feed ingredients (fisheries by-products, insect meal and fermentation biomass). Turbot from the CTRL group had a similar growth and feed performance than fish fed the NoPAP30 formulation, with a significant decline of performance in the fish fed both PAP formulations and the NoPAP60. Comparing the two formulation concepts with each other the voluntary feed intake and protein efficiency ratio on tank basis as well as the individual weight gain and relative growth rate was significantly higher in the fish from the NoPAP groups than PAP groups. Furthermore, the apparent digestibility of nutrients and minerals was significantly reduced in the fish fed with the diets with 30% and 60% fishmeal replacement level compared to the fish from the CTRL group. In conclusion, the performance of the fish fed the NoPAP30 formulation concept highlights the potential of the used combination of sustainable ingredients, such as fisheries by-products, insect meal, microbial biomass and plant protein for turbot. Furthermore, this study shows that turbot has a higher tolerance to the incorporation of plant and insect protein than of processed animal protein.publishedVersio

Sustainable fish feeds: potential of emerging protein sources in diets for juvenile turbot (Scophthalmus maximus) in RAS

In Europe, turbot aquaculture has a high potential for sustainable production, but the low tolerance to fishmeal replacement in the diet represents a big issue. Therefore, this study investigated the effects of more sustainable feed formulations on growth and feed performance, as well as nutritional status of juvenile turbot in recirculating aquaculture systems. In a 16-week feeding trial with 20 g juvenile turbot, one control diet containing traditional fishmeal, fish oil and soy products and two experimental diets where 20% of the fishmeal was replaced either with processed animal proteins (PAP) or with terrestrial plant proteins (PLANT) were tested. Irrespective of diets, growth performance was similar between groups, whereas the feed performance was significantly reduced in fish of the PAP group compared to the control. Comparing growth, feed utilisation and biochemical parameters, the results indicate that the fish fed on PAP diet had the lowest performance. Fish fed the PLANT diet had similar feed utilisation compared to the control, whereas parameters of the nutritional status, such as condition factor, hepato-somatic index and glycogen content showed reduced levels after 16 weeks. These effects in biochemical parameters are within the physiological range and therefore not the cause of negative performance. Since growth was unaffected, the lower feed performance of fish that were fed the PAP formulation might be balanced by the cost efficient formulation in comparison to the commercial and the PLANT formulations. Present study highlights the suitability of alternative food formulation for farmed fish

Alternative Feed Formulations Impact Growth Performance, Flesh Quality and Consumer Acceptance of Rainbow Trout (<i>Oncorhynchus mykiss</i>)

This trial aimed to assess the growth performance of trout (Oncorhynchus mykiss) fed novel formulations, evaluate fish welfare status, and determine flesh quality as part of the evaluation of sustainable feeds. A control diet containing fish meal and soy products (CTRL) was compared to: a diet with processed animal proteins (PAP); a diet without PAP (NoPAP); a PAP diet lower in protein (PAP−); and a NoPAP diet higher in protein (NoPAP+). Groups of 50 fish, weighing 58.84 ± 1.39 g (IBW), were allocated to 20 tanks and fed with formulated diets ad libitum over 91 days. Better growth performance was observed after the experiment in fish fed the NoPAP+ diet when compared to other diets. Protein retention was higher in CTRL diets than in PAP and PAP− diets. Protein and phosphorous digestibility were lower in fish fed PAP− diet. Diets did not influence the texture analysis. However, sensory analysis revealed higher acceptance for fish fed the NoPAP diet when compared to the PAP diet. Lysozyme was higher in the NoPAP diet than in other treatments. In addition, long-term predictions using FEEDNETICSTM software suggest some of these alternative formulations may be economically sustainable. Overall, these results support the hypothesis that the new formulations are viable options for trout farming