Growth performance and nutrient utilization of growth hormone transgenic female triploid Atlantic salmon (Salmo salar) reared at three temperatures in a land-based freshwater recirculating aquaculture system (RAS)

This study examined the effect of rearing temperature on growth performance and nutrient utilization of AquAdvantage Salmon (growth hormone transgenic female triploid Atlantic salmon) reared in a land-based freshwater recirculating aquaculture system (RAS) at three temperatures (10.5 degrees C, 13.5 degrees C, 16.5 degrees C) from first-feeding to 1500 g. All fish were fed the same commercial diets, which were analyzed for proximate, amino acid, fatty acid and mineral composition, and daily feed consumption was recorded for the calculation of feed conversion ratios (FCRs). Whole-body samples were collected at 300, 500, 800 and 1500 g for proximate composition, and fillet samples were collected at 500, 800 and 1500 g for amino acid, fatty acid, and mineral composition. Fillet yield, astaxanthin concentration and DSM SalmoFan (TM) colour were determined at 1500 g. Results indicated that fish reared at 16.5 degrees C required more feed per unit of biomass gain, and were less efficient at depositing important nutrients such as omega-3 fatty acids, compared to salmon reared at 10.5 degrees C and 13.5 degrees C. With higher viscerosomatic index (VSI) and condition factor (K) scores at 16.5 degrees C, these fish also diverted more dietary energy to lipid deposition in the viscera instead of muscle tissue compared to the lower temperature treatments. Fish reared at 16.5 degrees C had lighter fillet colouration compared to salmon reared at 13.5 degrees C, and exhibited lower fillet yields than the colder temperature groups. Fish reared at 16.5 degrees C reached the end target weight (1500 g) in 36 fewer days compared to 13.5 degrees C and 93 fewer days in contrast to 10.5 degrees C. However, thermal-unit growth coefficient (TGC) results indicated that growth rate was higher in fish reared at 10.5 degrees C compared to 16.5 degrees C for the majority of the trial. Collectively, these results suggest that it is preferable to rear AquAdvantage Salmon at either 10.5 degrees C or 13.5 degrees C in freshwater RAS. The information generated from this study is the first to provide insight into the relationships between rearing temperature and nutrient utilization in AquAdvantage Salmon for commercial application.