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 grow th-enhanced transgenic salmonid fish, prior to commercial implementation of this technology, there is a need for further information relating to the p hysiology of a number of commercially important production traits. Growth r ate, feed digestibility, feed conversion, and body composition of F-2 gener ation growth-enhanced transgenic Atlantic salmon were therefore compared wi th that of non-genetically modified salmon, 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 over the body weight inter val examined. Daily feed consumption over this body weight interval was 2.1 4- to 2.62-fold greater for the transgenic fish compared to the control fis h. Transgenesis did not affect the extent to which protein and energy were digested, with digestibility coefficients 88% and 81%, respectively for tra nsgenic fish, and 90% and 84%, respectively for control fish, both measured over comparable body weight intervals. However, transgenic salmon relative to control fish exhibited a 10% improvement in gross feed conversion effic iency. Body protein, dry matter, ash, lipid and energy were significantly l ower in the transgenic salmon relative to controls while moisture content w as significantly higher. The transgenic experimental subjects used throughout the present study poss essed the physiological plasticity necessary to accommodate an acceleration in growth well beyond the normal range for this species with few effects o ther than a greater appetite and a leaner body. (C) 2000 Elsevier Science B .V. All rights reserved.