Characterization of Growth Physiology through Gene Expression in Rainbow Trout (Oncorhynchus mykiss) Fed Bioprocessed Soy-Based Diets

The inclusion of soybean meal to replace marine-derived fish protein (MDFM) within aquafeeds has become of great interest to fish producers.  Furthermore, the bioprocessing of these plant-based proteins may increase protein levels, digestibility, and remove antinutritional factors present in the base ingredient. A 14-day feeding trial aimed to investigate physiology and endocrinology of growth performance in rainbow trout Oncorhynchus mykiss fed bioprocessed soybean meal.  Two experimental diets contained 10 and 15% inclusions of bioprocessed soybean meal and a fishmeal diet was used as a reference. Juvenile rainbow trout (38.1g) were stocked at 8 fish/tank in 32, 110L tanks within a recirculating aquaculture system.  Trout were fed 4% of body weight, divided into 3 equal feedings at 8am, 12pm, and 4pm daily.   Trout were sampled on days 0, 7, and 14 and exact sampling times were staggered for each tank (4h following the morning feeding) to minimize experimental error associated with sampling circulating IGF-1 levels. RT-PCR analyses is being performed to determine expression levels of IGF-1, growth hormone (GH), and myosin heavy chain (MyHC) within the tissue samples.  Trial results are expected to elucidate both diet-based and short-term changes in growth physiology for cultured juvenile rainbow trout.