Genetics of performance in the horse

Area of Science:

• Equine Science
• Animal Genetics
• Performance Trait Analysis

Background:

• Estimating genetic differences in horses requires understanding performance measures, environmental influences, and heritability.
• Heritability provides insight into the proportion of phenotypic variation attributable to additive genetic effects.

Purpose of the Study:

• To summarize published heritability estimates for various equine performance traits.
• To provide a basis for understanding the genetic components of different performance measures in horses.

Main Methods:

• Literature review and synthesis of published heritability estimates.
• Categorization of heritability estimates by performance discipline and breed (Thoroughbred, trotter, pacer).

Main Results:

• Heritability estimates for pulling and cutting ability were 0.25 and 0.04.
• Jumping, 3-day event, and dressage performance showed heritability estimates of 0.18, 0.19, and 0.17.
• Thoroughbred traits like performance rates (0.55) and log of earnings (0.49) had higher heritability than earnings (0.09).
• Trotter traits like log of earnings (0.41) and best time (0.25) showed moderate heritability.

Conclusions:

• Heritability estimates for horse performance traits are diverse, ranging from low to moderate.
• The effectiveness of genetic selection depends on the specific performance trait targeted for improvement.
• These estimates are vital for informed breeding decisions and predicting response to selection.