Farmed salmonids are an important dietary source of vitamin D for consumers, yet their vitamin D content varies significantly depending on feed formulation. Regulatory
changes in the EU, have raised the maximum permissible vitamin D3 levels in fish feed, prompting interest in understanding its transfer efficiency from feed to fillet.
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. The research was conducted by BioMar’s R&D team in Denmark between July and September 2022, over a 61-day feeding period.
Ten dietary treatments were tested with increasing levels of synthetic vitamin D3, ranging from 8,100 to 77,400 IU/kg feed. Fish performance parameters, nutrient retention, and fillet pigmentation were assessed to determine safety, efficacy, and potential nutritional benefits.
Figure 1. Regression analyses of dietary vitamin D3 (IU/kg) levels and feed intake (IU/Kg fish) (a); fillet content of vitamin D3 (IU/Kg fish) (b); whole body content of vitamin D3 (IU/Kg fish) (c). Dots represent the mean of the experimental treatments (n=2 in D1 and n=1 in the rest).
The study found that increasing dietary vitamin D3 levels did not affect growth performance, including feed intake, specific growth rate, or feed conversion ratio. This confirms that vitamin D3 supplementation is safe at the tested levels.
Although growth was unaffected, vitamin D3 supplementation significantly improved vitamin D3 deposition. Fillet vitamin D3 content increased proportionally with dietary levels, supporting targeted enrichment strategies to enhance the nutritional value of the final fish product for consumers.
Fillet pigmentation, as measured by MINOLTA a* values, increased linearly with higher dietary vitamin D3 supplementation levels, indicating a potential improvement in fillet redness, although this effect was not statistically significant. Overall, vitamin D3 supplementation maintained fillet appearance while supporting enrichment strategies.
Figure 2. Regression analyses of dietary vitamin D3 (IU/kg) levels and MINOLTA parameters (A.U.) measured in the fillets from fish fed the experimental diets for 61 days. Dots represent the mean of the experimental treatments (n=2 in D1 and n=1 in the rest).
These findings demonstrate that farmed rainbow trout fillets can be effectively enriched with vitamin D3 through feed formulation without compromising growth or feed efficiency. From a consumer perspective, this enhances the nutritional value of farmed fish, addressing widespread dietary vitamin D deficiencies in human populations.
The study highlight that targeted vitamin D3 supplementation in trout feeds improves fillet nutritional quality while maintaining production performance. As consumer focus grows on nutritional fortification and sustainable aquaculture practices, optimizing feed formulations for micronutrient enrichment will support market differentiation and public health goals.
Results (8)
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.
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.
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.
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.
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.
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 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.