Drawbacks and consequences of selective strategies in the design of semen banks: Case study of the Pura Raza Espanol horse breed

• Genome resource banks (GRB) are valuable tools for the maintenance of genetic diversity, especially in endangered species or local breeds but also for mainstream breeds. Minimum coancestry criterion is commonly implemented to decide the actual donors contributing to the GRB. This is (more or less) clear for local breeds with a pure conservation emphasis. However, in breeds with a productive or commercial nature other considerations are also taken into account beyond the original objective of the bank, For instance, the breeding criteria used in the living population for the maintenance of the genetic progress could be also implemented in the design of the bank. Using data of the Pura Raza Espahol (PRE) horse breed (males between 3 and 20 years old) as a case study, we aimed to investigate the effect on genetic diversity of different criteria for the selection of the donors (stallions) in the design of a GRB (semen bank). Studied scenarios included (i) minimisation of the global average coancestry; (ii) maximisation of the mean estimated breeding values (EBVs) of the donors with a restriction on the levels of coancestry incurred. We used genealogical (281,052 animals; 138,059 males and 145,869 females) and molecular information (70,572 genotypes from PRE with reproductive capacity), as well as the EBVs for two productive traits (Dressage sport discipline of 9000 males and morphological linear traits of 2597 males). When the genealogical coancestry was the only criterion, increasing the number of donors resulted in continuous increase in diversity stored (for the different parameters used for comparison). When pedigree coancestry was replaced by molecular coancestry results were not so consistent. The inclusion of EBVs as additional selective criteria (searching for the most 'valuable' donors) led to an increased relatedness between donors (and, correspondingly, to a decrease in the diversity kept). In this scenario, the inclusion of individuals with low performance may be arguable depending on the time horizon the bank has been designed for. In any case, in parallel as it is recommended for the management of living populations, restrictions in the levels of genetic diversity (inbreeding) should be included when deciding the sampling scheme.

Ämnesord

LANTBRUKSVETENSKAPER  -- Husdjursvetenskap -- Husdjursvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Animal and Dairy Sience -- Animal and Dairy Science. (hsv//eng)

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