High-Linolenic Acid Transgenic Rapeseed Oil in Feed Boosts Antioxidant Capacity, Mitigates Visceral Lipid Accumulation, and Elevates Nutritional Quality of Yellow Catfish (Pelteobagrus fulvidraco)

Freshwater fish are an important source of high-quality fats for humans, and they can efficiently convert α-linolenic acid (C18:3n-3) endogenously into n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). We assessed the application of transgenic rapeseed oil (RO) with high α-linoleic acid (C18:3n-3) content (28.46%–53.57%) in aquaculture feed. We designed four diets with various lipid levels and C18:3n-3 contents: low-fat RO, high-fat RO, low-fat high C18:3n-3 RO, and high-fat high C18:3n-3 RO. After an 8-week feeding trial, we assessed their effect on the fatty acid composition, lipid deposition, and muscle flavor of yellow catfish (Pelteobagrus fulvidraco). Weight gain did not differ significantly between the high and low C18:3n-3 groups regardless of lipid levels. High C18:3n-3 RO feed influenced the expression patterns of liver lipid metabolism–related genes, effectively preventing lipid accumulation in the visceral and liver tissues. Additionally, high C18:3n-3 RO diets significantly increased antioxidant levels in both the liver and serum compared to low C18:3n-3 diets, while also increasing n-3 LC-PUFA content in the liver and muscle tissue and improving muscle flavor. Overall, a high C18:3n-3 RO diet improved the health, antioxidant performance, and nutritional components of yellow catfish.

Practical Applications: This study highlights the potential of metabolically engineered RO rich in C18:3n-3 as a sustainable alternative to fish oil in aquafeeds. The knowledge gained in the present study will provide valuable insights for the aquaculture industry, suggesting a viable strategy for reducing reliance on traditional fish oils while maintaining or improving the nutritional profile of fish.