Effects of integrated genetic evaluations for Icelandic horses on predictive ability, accuracy and selection bias.

This research examines the effect of integrating competition traits and test status into the genetic assessment of Icelandic horses. The study indicates that integrating these aspects could enhance the accuracy of genetic evaluations and slightly alter the ranking of sires. However, comprehensive parameters regarding test status and its interconnectedness with other traits require further analysis for future inclusion in genetic evaluations.

Research Methodology and Data

• The researchers used breeding field test data from 19,954 records obtained from horses evaluated in 11 countries from 1994 to 2008.
• They also incorporated competition data from 44,160 records involving 7,687 horses that took part in competitions in Iceland and Sweden from 1998 to 2008. Test status was determined by the presence of horses born in Iceland at breeding field tests and/or in competition.

Findings

• Minimal differences were observed between various genetic evaluation models concerning estimation bias and predictive ability.
• There were shallow correlations calculated between breeding values for combined indexes of conformation, riding ability, and total score across different models.
• Most of the traits showed higher accuracy when competition traits and/or test status were added to the evaluation model.
• The ranking of sires differed when new traits were incorporated into the genetic evaluation model.

Conclusion and Future Implications

• The study concluded that competition traits should be integrated into the genetic evaluation to improve accuracy.
• However, further analyses are needed on the relationship between test status and other traits before including the test status in the genetic evaluation process.