Implementation of Optimum Contributions selection in endangered local breeds: the case of the Menorca Horse population.

The research article discusses the implementation of Optimal Contribution selection to improve the dressage performance of a small breed of horse, the Menorca Horse, while limiting inbreeding. The study indicates that it’s possible to achieve satisfactory genetic gain without significantly increasing inbreeding, using pedigree and molecular coancestry information.

Research Methodology & Scope

• The focus of the research is primarily on the Menorca Horse population, a small breed where maintaining genetic diversity is critically important.
• As dressage performance is crucial to the economic profitability of this breed, the researchers seek to improve this trait while restraining the rate of inbreeding (∆F).
• The researchers include horses between 3 and 20 years in the breeding pool for their experiment.
• This study employs Best Linear Unbiased Prediction or BLUP – a method for the estimation of random effects in a mixed linear model – to calculate estimated breeding values for dressage.

Findings

• The research revealed it is feasible to prevent sharp increases in inbreeding while achieving desirable levels of genetic gain in the Menorca Horse population, suggesting the breed is suitable for Optimal Contribution selection.
• A 1% increase in inbreeding (∆F) would result in a maximum 2% fall in genetic gain, which is an acceptable trade-off.
• Both pedigree and molecular coancestry were utilized to calculate relationships among potential breeding horses. It was found that using molecularly derived information could lead to a broader range of solutions to maximize genetic gain as compared to using pedigree coancestry. The increase in genetic gain was 1-4% higher for the same levels of inbreeding with the use of molecular data.

Significance and Implications

• The results of this study are significant as they provide evidence that careful management can lead to improved performance traits in small horse populations, such as the Menorca Horse breed, while controlling inbreeding.
• By using molecular coancestry information as a basis for breeding selection, geneticists and breed managers could optimize both the response to selection and the levels of variability and inbreeding.
• This research has implications for the conservation and improvement of other small, local breeds, suggesting that with mindful breeding strategies, it is possible to achieve genetic gains while preserving genetic diversity.