Better Growth in All-Female Diploid and Triploid Rainbow Trout

Abstract

Abstract We compared growth of all-female triploid (AFT; 87% triploid), all-female diploid (AFD), and mixed-sex diploid (MSD) rainbow trout Oncorhynchus mykiss in a 265-d growth trial. Triploidy was induced by heat-shocking eggs to prevent second polar body exclusion. Three AFT families, three corresponding full-sibling AFD families, and three MSD families that were half-siblings of the AFD and AFT families were used. Mean initial weights (SD) were 94 g (14), 84 g (12), and 112 g (14) for the MSDs, AFDs, and AFTs, respectively, and final weights (SD) were 521 g (22), 568 g (68), and 749 g (30). Growth was linear. Growth was highest for the AFTs (2.38g/d), lowest for the MSDs (1.58 g/d), and intermediate for the AFDs (1.78 g/d). No significant differences (P > 0.05) were found among treatments for survival, food conversion ratio, condition factor, liversomatic index, viceral fat, and dress-out. By day 180, however, the majority of the MSD males were sexually mature, whereas the MSD females and the AFDs wer...