Feasibility of including refined soy-products to produce a soy-maximized feed for hybrid striped bass (M. chrysops x M. saxatilis)

Many sources of protein have been investigated to reduce the use of fishmeal (FM) in aquaculture feeds, including soybean meal (SBM).  However, FM replacement in feeds for carnivorous species is limited by problems with feed intake, growth rate, and overall health associated with reduced digestibility and anti-nutritional factors found in SBM.  However, soy processing strategies can reduce the effects of anti-nutritional factors and improve utilization.  Therefore, we examined the possibility of further FM replacement in SBM maximized feeds for hybrid striped bass using refined soy products, soy protein concentrate (SPC) and soy protein isolate (SPI)

Results indicate that further FM sparing is possible with SPC or SPI, beyond what can be achieved with SBM.   For example, it is possible to reduce dietary FM content as low as 5% using SPC, and though this negatively affects growth rate, this effect may reversed by the addition of a betaine-based attractant/palatant.  Although statistical significance was not resolved in all cases, reducing FM content below 5-10% results in more variable production performance and cannibalism.  In addition to production performance, effects of these alternative proteins on stress tolerance, as well as the potential for betaine to act as a hepatoprotectant, will be discussed.