Growth rate, body composition and feed digestibility/conversion of growth-enhanced transgenic Atlantic salmon (Salmo salar)

Although dramatic improvements in growth rates have been documented in growth-enhanced transgenic salmonid fish, prior to commercial implementation of this technology, there is a need for further information relating to the physiology of a number of commercially important production traits. In 1996 at AquaBounty Farms (Prince Edward Island, Canada) growth rate, feed digestibility, feed conversion, and body composition of F2 generation growth-enhanced transgenic Atlantic salmon (n = 660) were therefore compared with that of non-genetically modified salmon (n = 660), over a presmolt growth interval of 8-55 g. The growth-enhanced transgenic fish exhibited a 2.62- to 2.85-fold greater rate of growth relative to non-transgenic salmon. Daily feed consumption was 2.14- to 2.62-fold greater for the transgenic fish compared to the control fish. Transgenesis did not affect the extent to which protein and energy were digested, with digestibility coefficients 88% and 81% respectively for transgenic fish, and 90% and 84% respectively for control fish, both measured over comparable body weight intervals. Transgenic salmon, relative to control fish, exhibited a 10% improvement in gross feed conversion efficiency. Body protein, dry matter, ash, lipid and energy were significantly lower in the transgenic salmon relative to controls while moisture content was significantly higher. The transgenic experimental subjects used throughout the present study possessed the physiological plasticity necessary to accommodate an acceleration in growth well beyond the normal range for this species with few effects other than a greater appetite and a leaner body..