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

Abstract

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.

Country-specific food culture and scientific knowledge transfer events – Do they influence the purchasing behaviour of seafood products?

“…Surprisingly, very few studies explore an interactive approach, despite that posters are standard tools at scientific conferences ( Diebold et al, 2017 ; Mabrouk and Schelble, 2018 ). In addition, previous attempts to motivate scientists to conduct online surveys at conferences are highly challenging (see Hoerterer et al, 2022b ). This can be related to the observation that people are rather unwilling to undergo an online survey whilst being more motivated to look at posters and indicate their preferences briefly in an easily accessible manner.…”

“…The participants consisted of scientists with or without an aquaculture background, aquaculture operators, students, and laypeople across different age groups and with varying levels of scientific knowledge about seafood products. For the latter, detailed online surveys were conducted, and findings were collated and analysed in Hoerterer et al (2022b) . Of these, 383 filled in the more detailed questions on seafood purchasing criteria, next to the questions on species preferences.…”

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

“…The use of circular-economy (CE) driven feed ingredients based on other protein sources available in Europe, such as rapeseed, pea, microbial meals, and land-animal proteins, can reduce the conflict of use with human nutrition, diversify supply, and provide a viable alternative to FM and soybeans [ 3 ]. All of the above-mentioned alternative feed ingredients have been assessed in various feeding trials with high-trophic fish focusing on key performance indicators, such as growth, feed conversion, nutrient retention, digestibility, and somatic indices [ 4 , 5 , 6 , 7 , 8 , 9 ]. However, turbot is strictly carnivorous during its life cycle [ 10 ] and has a high demand for protein (55%) [ 11 ] and, depending on the alternative protein sources used, significant effects on growth, feed performance and organismic parameters were observed at replacement levels of more than 30–35% for juvenile turbot [ 12 , 13 , 14 , 15 ].…”

“…In a preceding feeding trial [ 7 ], growth and feed performance were not affected or only slightly affected, whereas the nutritional status was affected by the feed formulations. To elucidate the effects of the protein sources and the level of FM replacement on the metabolic profile, in this study, a diet with a balanced mixture and higher level of FM replacement was included.…”

Development of fish feeds for African catfish (Clarias gariepinus Burchell 1822) farming in Sierra Leone, West Africa

“…Thus, the anticipated success desired for the sector will significantly depend on providing quality and least cost fish feed (Delgedo and Minot, 2003). Glencross et al (2020) cited by Hoerterer et al (2021) posited that the challenge of feeding farmed fish with diets that are nutritious but at the same time economically and environmentally sustainable is a major issue to ponder.…”