A FUNCTIONAL FEED SOLUTION TO COMPENSATE FISH MEAL REDUCTION AND ASSOCIATED NUTRITIONAL STRESS IN SEABREAM Sparus aurata

Aquaculture production has undergone remarkable growth during the past few decades, and it will continue to rise in the coming years to meet higher demand for safe and healthy seafood products. 

For economic, environmental and societal reasons, a lower usage of finite marine-harvested resources has been a major trend in the aquafeed industry. Grain and oilseed by-products are promising sources of protein and energy for aquaculture feeds. However, high dietary inclusion levels of plant proteins have often been associated to detrimental effects on growth.

 In the scope of this sustainable approach, Mixscience  (France)  developed a specific  Phytogenics based  solution that helps to reduce the negative impact of challenging feeds .

The aim of this study is to examine the impact of this new solution on the zootechnical performance, nutrient digestibility, intestinal mucosal health and stress resilience in gilthead seabream ( Sparus aurata) challenged by a nutritional stress and some additional environmental stress.

The Seabream trial includes 3 treatments.

• A positive control (PC) = optimal diet for the targeted fish
• A negative control (NC) with lower levels of digestible protein and digestible energy due to fish meal replacement by challenging ingredients derived from defatted soybean meal and sunflower meal, which tend to reduce digestibility and negatively affect intestinal integrity.
• An additional diet, based on the NC formula, supplemented with the tested product (PHY) at a dose of 200 g/tonne of feed

The growth assay includes two distinct experimental phases. During the first 62 days, the fish are raised under normal breeding conditions to allow optimal zootechnical performance.

Subsequently, the fish are subjected to stressful rearing conditions for 12 days, which involve a combination of a high density stress for 10 days and 2 additional days under oxygen reduction. Apparent nutrient digestibility and stress response are measured alongside the performance trial.

The results clearly indicate that in seabream, a challenging food (NC) induces negative metabolic reactions: reduction of overall immune status, reduction of antioxidant defenses, degradation of intestinal homeostasis with particular deterioration of intestinal morphology (Figure1). This outcomes in lower feed efficiency, and performance of fish (Table 1). The negative impact of a challenging feed can be compensated by specific phytogenics that activate key metabolic activities to save energy and maintain overall resistance that limits dysbiosis and intestinal disorders under stressful conditions and helps maintain a healthy optimal feeding efficiency and an overall fitness of the host.