Genetic parameters of production traits (growth, carcass yield, fillet yield) and bony tissues (head and vertebral axis) were estimated for large all-female rainbow trout Oncorhynchus mykiss reared in freshwater. Genetic parameters were estimated using REML at 16 months of age (1636 g) on 1962 DNA-assigned progenies from a partial factorial mating design with 60 dams and 100 sex-reversed sires. Highlights► Genetic parameters of production traits in rainbow trout ► Negative correlation between production traits and bony tissues ► Selection on fillet yield

The use of marker-based pedigrees is increasing in aquaculture breeding, and obtaining high assignment rates is necessary for practical use of this methodology. In this paper, we used 12 real parentage assignment datasets from three species (European sea bass Dicentrarchus labrax, common carp Cyprinus carpio and rainbow trout Oncorhynchus mykiss) to investigate the relationships between theoretical, simulated and real assignment power. We found out that there was a large decrease between the theoretical and the observed values, which we modeled in four independent steps: 1) from theoretical values to population-wise simulations (− 2.8% on average), 2) from population-wise simulations to true parent set specific simulations (− 2.6% on average), 3) from true parent-set specific simulations to observed values in offspring with valid genotypes at all loci (− 0.5% on average) and 4) from observed values in offspring with valid genotypes at all loci to observed values in all offspring sampled (− 2.4% on average). For all steps, we provide a regression equation which models the loss of assignment power, or at least a maximal practical value for the loss of assignment power. Finally, equations are provided to model the expected true assignment rate from the theoretical assignment power or from the combined exclusion probability of the loci used. They show that the expected true assignment rates are considerably lower than the theoretical ones, for example achieving 99% true assignment requires a theoretical assignment power of 99.999996%, while 95% already requires 99.9989% theoretical assignment rate.

a b s t r a c tApplication of DNA parentage assignment for commercial selection in aquaculture is still rare. An experiment was performed to quantify and to minimize maternal effects on growth in rainbow trout. Six hundred families were reared until 198 day post fertilization (dpf) according to two different procedures. In the first procedure (NORM), all families were pooled at eyed stage. In the second procedure (MIN), where maternal effects due to differences in egg size were expected to be minimal, the spawns were divided into sub-groups with similar mean egg weight at eyed stage. These sub-groups were then pooled when they achieved the same mean body length (147 dpf). Genetic parameters were estimated for body weight, body length and condition factor at 198 dpf, with 2964 fish assigned to their parents using microsatellites. Significant maternal effects were observed in the NORM group for body weight and body length (m 2 ¼ 0.08 7 0.03). The heritability of body weight was 0.16 7 0.07 in the NORM group and 0.367 0.06 in the MIN group, in which maternal effects were not significant. It is concluded that, when eggs of different females are mixed at eyed stage, maternal effects persist at least until 198 dpf. The proposed procedure efficiently limits maternal effects, substantially increasing the heritability for growth, and therefore the expected selection response.

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Depuis 1991, des entreprises françaises sélectionnent la truite arc-en-ciel, la truite fario, le bar, la daurade et le turbot. Les éleveurs ont développé une expertise collective en matière de génétique quantitative, de contrôle de parenté assisté par empreintes génétiques, de monosexage, d’induction hormonale de la ponte, de triploïdisation et de conservation et congélation des gamètes, dans le cadre du Syndicat des Sélectionneurs Avicoles et Aquacoles Français (SYSAAF). Cette domestication s’appuie sur le transfert de la procédure de sélection sur la croissance PROSPER, élaborée par l’INRA, complétée de critères de sélection sur la qualité des carcasses (teneur en lipides des filets, rendement à l’éviscération) et d’une reproduction généalogique assistée par empreintes génétiques. L’amélioration des carcasses et de la chair est aussi réalisée par monosexage et triploïdisation. Depuis 2000, le transfert de la congélation du sperme est effectif. En 2003, entre 80 % et 100 % de la production française bénéficie de juvéniles provenant de programmes de sélection.