Effect of food deprivation on oxygen consumption and body composition of growth-enhanced transgenic Atlantic salmon (Salmo salar)

The influence of food deprivation on the rate of oxygen consumption and the rate of mobilization/utilization of energy reserves in F2 generation growth-enhanced transgenic Atlantic salmon were compared relative to their non-transgenic counterparts, over a pre-smolt weight interval of 8 to 55 g. Throughout most of the 8 weeks of food deprivation, transgenic fish exhibited a greater rate of oxygen consumption compared to control salmon, but also exhibited a more rapid decline in oxygen consumption as starvation progressed. Consequently, depending on initial weight and length of food deprivation, the rate of oxygen consumption of transgenic fish declined to where it equalled or was less than the oxygen consumption of control fish. Transgenic fish depleted body protein, dry matter, lipid and energy at a faster rate than did the controls. Additionally, in both groups, lipid was catabolized faster than was protein. Although transgenic fish demonstrated the ability to reduce their metabolic rate during starvation, as also observed in the non-genetically modified control salmon, their persistence in maintaining a higher metabolic rate, combined with their lower initial endogenous energy reserves, suggests that the likelihood of growth-enhanced transgenic salmon achieving maximum growth or even surviving outside intensive culture conditions may be lower than that of non-transgenic salmon..