Effect of grape pomace on growth, digestibility, antioxidant capacity and fatty acid profile of white shrimp (Litopenaeus vannamei) given diets free of fish-products

The global aquaculture sector is increasingly adopting sustainable aquafeeds that incorporate alternative nutritional resources, such as agricultural byproducts like grape pomace, a common byproduct from wineries that is seldom utilized in animal feed. This study aims to evaluate the effect of grape pomace (GP) on growth performance, nutritional profile, apparent digestibility, antioxidant capacity, and fatty acid composition in white shrimp (Litopenaeus vannamei) in diets free of fishmeal and fish oil. Four iso-proteinic and iso-lipidic diets (43% protein and 8% lipid) were supplemented with grape pomace at 0%, 1%, 2.5%, and 5%, replacing cornstarch. In a recirculation system composed of twelve tanks with a 500 L capacity, nineteen juvenile shrimp (1.20 ± 0.02 g) were distributed per tank, and fed the experimental diets for 63 days in triplicate. The 2.5% GP increases growth and specific growth rate (SGR) without negatively impacting survival. The inclusion of GP modifies the lipid and protein content on muscle, while improving the protein, and lipid apparent digestibility. Additionally, the inclusion of GP raised the level of polyphenols in the muscle, with effects on non-enzymatic antioxidant capacity. Our findings suggest that the optimal inclusion level for growth was identified at 2.68%, using a broken line method, which provides an additional 209.4 mg Kg⁻¹ of polyphenols.