Résumé
Introduction Fish selection for/or against fillet fatness required sib selection to measure lipids in the fillets or alternative indirect technologies usable on live candidates. Genetic parameters of different fillet adiposity components were evaluated by MRI (total fat; dorsal or ventral subcutaneous fat representing different trimming losses), artificial vision with A3 scanner (myosepta surfaces, dorsal or ventral or subcutaneous fat) and Fat Meter (external indirect measure applicable on live fish) technologies to optimize sib or individual selection on fillet adiposity. Methods 1625 rainbow trout from a partial factorial mating design of 90 dams x 100 sires (900 families) were slaughtered at 18 months old (1580g), processed and pedigree assigned with microsatellites. Genetic parameters were estimated with animal model (VCE). Results Heritabilities of myosepta (0.15-0.29) and adipose tissues surfaces (0.37-0.43) estimated with artificial vision are intermediates, as those of Fat Meter measures (0.38-0.45). Heritabilities of the total fat in the fillet or of the subcutaneous fat reported to the total surface of the cutlet or the dorsal or ventral related surfaces estimated with MRI were highest (h2> 0.60). The genetic correlations between total fat and the relative surface of subcutaneous fat are intermediate (0.64) and higher between the Fat Meter measure and the relative subcutaneous fat surface (0.77) than the total fat (0.43). Discussion All components of the fillet adiposity exhibited intermediate heritability. The two time lower heritability of the Fat Meter measure in this experiment and its intermediate genetic correlation with the total fat of the fillet is making selection on this indirect trait less efficient than selection on sibs. The high genetic correlation with the relative subcutaneous fat informed that the Fat Meter estimates mostly this later trait in large rainbow trout. MRI and artificial vision technologies are then recommended for more efficient selection programs in large fish to manipulate filet adiposity of trimming yields.