Effects of omega-3 fatty acid supplementation on aquaponic system-raised tilapia (Oreochromis niloticus x Oreochromis aureus ) physiology, immunology, and muscle tissue retention

Aquaculture and aquaponics are becoming important industries worldwide for both economic and social reasons. Tilapia does not naturally contain high levels of omega-3 fatty acids and previous research suggests this can be altered through feed supplementation. A higher level of omega-3 fatty acids in the fish is of benefit to the humans consuming them and potentially to the fish as well. This study evaluates the potential health effects of omega-3 fatty acid supplementation on tilapia and the ability of supplementation to increase the omega-3 fatty acid retention in muscle tissue. Tilapia ( Oreochromis niloticus x Oreochromis aureus) were fed linseed oil (LO) and sunflower oil (SO) supplemented feeds for 12 weeks and physiological parameters were measured at 0, 6, and 12 weeks. Omega-3 muscle tissue retention was measured at 12 weeks both in our lab and sent to an independent lab for analysis. All parameters were compared to a negative control (NC) at 12 weeks. Physiological parameters measured included condition factor, blood glucose, plasma protein, packed cell volume, spleen somatic index, and phagocytic activity. Blood glucose was significantly reduced in both LO and SO over time and significantly lower than NC. Packed cell volume and spleen somatic index were significantly reduced in LO and SO over time but were not different from NC. Plasma protein was significantly higher than NC for both LO and SO. Phagocytic activity was increased only in LO and was significantly higher than SO. LO retained more of some omega-3 fatty acids than SO, however they were not significantly different using either method. NC had higher total omega-3 values than LO and SO according to both methods; however NC also had the highest saturated and total fat. This study determined that health parameters in an aquaponics system are similar to those observed in an aquaculture system and higher dietary lipid levels confer some health benefits. The study also determined that omega-3 supplementation enhances phagocytosis. We were unable to conclusively determine the effect of supplementation on omega-3 retention