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

Abstract

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.

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

“…The effects of the two feed formulations, PLANT and PAP, on growth and feed performance and the nutritional status was reported in a previous publication [9]. 11 10.8 10.8 18.8 Rapeseed oil 12 46.4 34.4 34.4 Rapeseed lecithin 13 8 8 8 Vitamin and mineral premix 14 10 10 10 10 Vitamin C 15 0.5 0.5 0.5 0.5 Vitamin E 15 0.5 0.5 0.5 0.5 Betaine HCl 16 5 5 5 Macroalgae mix 17 5 5 5 Antioxidant 18 1.8 1.8 1.8 1.8 Sodium propionate 19 1 1 1 1…”

“…The effects of the two feed formulations, PLANT and PAP, on growth and feed performance and the nutritional status was reported in a previous publication [ 9 ].…”

“…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 ].…”

Exploring Sustainable Aquafeed Alternatives with a Specific Focus on the Ensilaging Technology of Fish Waste

“…Among commercially available animal protein alternatives, poultry by-product meal stands out for its excellent nutritional value and amino acid balance, although it may have lower levels of certain essential amino acids like lysine and methionine compared to fish meal [21][22][23]. The fermentation process has been used to reduce the presence of antinutritional factors in plant-based protein sources and potentially increase the nutritional quality of both animal-based and plant-based protein sources for use in aquaculture feeds [24]. By treating protein sources with appropriate microorganisms, their nutrients can be preserved and subsequently incorporated into aquafeed, potentially resulting in reduced feed costs and environmental pollution.…”