Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/8/2013
Publication Date: N/A
Technical Abstract: A forty week feeding study was conducted with Atlantic salmon (Salmo salar) smolts in two recirculating aquaculture systems. Twelve salmon (average initial weight 117 g; initial density 9.4 kg/m3) were stocked per tank. Two identical systems were used and contained either freshwater (0 ppt) or seawater (~30 ppt), with the temperature maintained at 13°C by heat pumps/chillers. Fish were fed one of two diets, a control diet containing fishmeal and fish oil, or a marine-free diet that did not contain fishmeal or fish oil. The diets were fed to 6 replicate tanks in each system. The feed conversion ratio [FCR] (1.14 to 1.29), SGR (0.63-0.66) or average weight gain (590-667g) did not differ significantly among dietary or water treatments. There was however, a significant diet × water interaction for average weight gain and fish fed the reference diet growing slightly better in seawater and fish fed the marine free diet growing slightly better in freshwater. The fish fed the marine-free diet had significantly lower whole body crude protein levels (54.4% to 59.4% ) compared to salmon fed the reference diet. There were no significant differences in whole body crude lipid (9.3% - 10.8%), moisture (66.9% - 68.7%), or ash (2.6% - 3.1%) contents. Diet and water salinity did not affect the texture of the fillets, but fish grown in seawater had significantly higher color scores compared to fish grown in freshwater (8.4 a* - 6.1 a*). Fillet yield was not significantly affected by diet. The diet did affect the fatty acid composition of the fillets. Fish fed the marine-free diet had significantly less eicosapentaenoic acid (20:5 n-3) (1.6% of lipids – 9.9% of lipids) docosahexaenoic acid (22:5 n-3) (0.5% of lipids – 3.2% of lipids) compared to fish fed the reference diet. The salinity of the water did not affect fatty acid composition of the fillets. Overall the salmon had similar performance regardless of diet or water salinity, but did appear to have more pigment in the flesh when grown in seawater.