Long-Term Impact of Optimum Contribution Selection Strategies on Local Livestock Breeds with Historical Introgression at the Example of German Angler Cattle

The long-term performance of different selection strategies was evaluated via simulation at the example of a local cattle breed, the German Angler cattle. Different optimum contribution selection approaches to maximize genetic gain were compared to a reference scenario without selection and truncation selection. The kinships and migrant contribution were estimated from genomic data. Truncation selection achieved the highest genetic gain but decreased diversity considerably at native alleles. It also caused the highest increase in migrant contributions. Traditional optimum contribution selection, which only constrains on kinship, achieved almost the same genetic gain but also caused a small increase of migrant contribution and remarkably reduced the diversity at native alleles. When migrant contribution was required not to increase and the increase of kinship at native alleles was restricted, the migrant contribution levels and the diversity at native alleles were well managed, and the genetic gain was only slightly reduced. However, genetic progress was substantially lower in the scenario that aimed at recovering the original genetic background. Truncation selection and traditional optimum contribution selection both reduce the genetic originality of breeds with historical introgression. The inclusion of migrant contribution and kinship at native alleles as additional constraints in optimum contribution selection showed great potential for conservation. Recovering the original genetic background is possible but requires many generations of selection and reduces the genetic progress in performance traits. Hence, constraining the migrant contribution at their current values can be recommended to avoid further reduction of genetic originality.

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