Efficient nutrient transfer from feed to fillet remains a key goal in sustainable aquaculture, particularly for micronutrients like vitamin D3 that carry both regulatory importance and consumer health value.
Farmed salmonids are among the top contributors of vitamin D in human diets, yet the levels in fillet vary widely depending on feed formulation and production conditions.
This study evaluated whether supplementing rainbow trout diets with synthetic vitamin D3 alone or combined with its bioactive metabolites could enhance vitamin D3 deposition in muscle tissue under freshwater recirculating aquaculture system (RAS) conditions. The trial ran for 61 days at BioMar’s ATC Hirtshals facility using 12 diets that varied by inclusion level and source of vitamin D3.
Ten cholecalciferol-based diets ranged from 8,100 to 77,400 IU/kg, and two additional diets included a combination of cholecalciferol (40,000 IU/kg) and either an ‘intermediate’ or ‘active’ Vit D metabolite at levels recommended by suppliers. All feeds were formulated with identical base composition and produced as 4.5 mm pellets.
Vitamin D3 retention (% intake) in the fillet from fish fed experimental diets for 61 days
No significant differences were observed in growth rate, feed intake, or feed conversion ratio across all treatments. Fish fed both synthetic vitamin D3 and combinations with its metabolite forms grew equally well, confirming that high-level supplementation and metabolite use are safe under commercial RAS conditions.
Vitamin D3 content in both fillet and whole body increased proportionally with dietary supplementation. Regression analyses confirmed a strong positive correlation between dietary cholecalciferol and vitamin D3 deposition (p < 0.001). The combination of cholecalciferol with ‘intermediate’ or ‘active’ Vit D metabolites also resulted in elevated fillet vitamin D3 levels, with the ‘active’ metabolite achieving higher deposition than synthetic vitamin D3, likely due to an apparent sparing effect in fat stores.
Fillet redness, assessed by MINOLTA a* values, increased linearly with higher vitamin D3 supplementation levels. Neither the ‘intermediate’ or ‘active’ metabolites negatively impacted pigmentation, and all treatments remained within the commercially acceptable range for fillet appearance.
Supplementation with vitamin D3 metabolites also influenced mineral uptake. Fish fed combinations of cholecalciferol with either the ‘intermediate’ or ‘active’ metabolite showed improved whole-body retention of zinc and iron compared to those fed synthetic D3 alone. A mild negative correlation was observed between dietary zinc levels and fillet vitamin D3 retention, expressed as a percentage of intake, suggesting a potential interaction between zinc availability and vitamin D3 utilization.
Whole body Zn retention (% intake) of fish fed the experimental diets for 61 days
This trial confirms that both synthetic and bioactive vitamin D3 sources can be used to safely enrich rainbow trout fillets without compromising growth or product quality. The use of the ‘active’ Vit D metabolite may
offer a cost-effective strategy to improve vitamin D3 retention in edible tissue. These findings support the development of feed solutions tailored for nutritional fortification in premium aquaculture products.
Results (11)
Mechanical delousing and other handling procedures are known to trigger acute stress in Atlantic salmon (Salmo salar), leading to reduced appetite, growth losses, and a weakened physiological condition.
This study explored how different levels of synthetic vitamin D3 (cholecalciferol) supplementation influence whole body and fillet vitamin D3 deposition in rainbow trout reared under recirculating aquaculture system (RAS) conditions.
Fish protein hydrolysates (FPH) are known to improve nutrient availability and immune function in early-stage fish. Their high content and mix of peptides of different sizes and single amino acids, although widely variable depending on the commercial source, makes them particularly suited for fry, whose gastrointestinal tracts are still maturing.
Largemouth bass (Micropterus salmoides) are a crucial freshwater aquaculture species in China, facing challenges like high water temperatures that cause significant economic losses. One promising solution is using functional feeds with natural antioxidants.
In the past, trimmings, viscera, and heads from fisheries were often discarded as waste. However, these side-stream products, are recognized as valuable resources that can contribute to sustainable aquaculture. While the utilization of pelagic fish side-stream products is well-established, side-stream products from whitefish remain underutilized.
Yellowtail kingfish (Seriola lalandi) is a highly valued marine species known for its rapid growth and high market price. Predominantly farmed in sea cages in regions such as Australia, New Zealand, Japan, and Mexico, this species is now being explored for recirculating aquaculture systems in Europe and the USA.
Managing sea lice infestations in Atlantic salmon (Salmo salar L.) aquaculture often involves mechanical treatments that can cause acute stress, reducing feed intake and compromising growth.
The global aquafeed industry has undergone a significant transformation over the past two decades, shifting from marine-based ingredients to plant-based raw materials. This transition has linked aquafeed production more closely with the environmental and social impacts of agriculture. Sustainable raw material sourcing is critical, given that aquafeed production accounts for up to 80% of the scope 3 greenhouse gas emissions in salmon farming.
Iron (Fe) is a crucial trace mineral involved in various biochemical processes in fish. For Atlantic salmon (Salmo salar L.), the dietary iron requirement ranges from 60 to 160 mg/kg. However, these requirements were established using purified diets with highly bioavailable iron forms, and may not reflect the needs in practical diets where interactions with antinutrients such as phytate can affect iron bioavailability.
Atlantic salmon (Salmo salar) farming industry frequently faces the challenge of managing sea lice infestations, which necessitates mechanical treatment procedures that can stress the fish. Handling stress from crowding and delousing can negatively impact fish appetite and growth, leading to economic losses.
The shrimp aquaculture industry faces significant challenges due to suboptimal culture conditions and susceptibility to opportunistic pathogens like Vibrio parahaemolyticus. Given the underdeveloped immune system of shrimp, these factors can lead to high mortality rates and economic losses.