Reprint of: Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout (Oncorhynchus mykiss)

In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25-0.28) that were half the value of heritabilities for real processing yields (0.47-0.55), but had high genetic correlations with these real yields (0.87-0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection.