Assessing the Effectiveness of Sex-Linked Molecular Markers to Identify Neomale Breeders for the Production of All-Female Progenies of Rainbow Trout

A cultured stock of masculinized rainbow trout was diagnosed with Y‐linked markers (sdY and OmyY1) aiming to detect neomales before their use at the production level. To achieve a reliable diagnosis, the following steps were considered: (1) PCR amplification of the housekeeping β-actin gene to determine the DNA quality of samples, (2) validation of the Y‐linked markers by their PCR amplification in male and female samples with known sex, and (3) molecular sexing of the masculinized juveniles based on male-specific (XY genotype) and neomale-specific (XX genotype) PCR product band patterns visualized on agarose gel. The validity and concordance of the markers were assessed. The housekeeping gene identified samples with negative PCR amplification revealing a poor DNA quality. The OmyY1 marker presented a more distinctive PCR product band pattern between males and females than the sdY marker and identified a higher proportion of true males (sensitivity = 1.0 and 0.91, respectively). The OmyY1 marker accurately identified 105 neomales of the 198 masculinized individuals on account their consistent and distinctive PCR product band pattern. Among both markers, there was a medium high positive concordance (γ index = 0.7). It is concluded that the OmyY1 marker shows the best performance to reliably detect neomales, a step that is essential to have certified breeders for the production of all-female progenies in fish farming.