Estimation of the heritability of lameness in standardbred trotters.

This research investigates the heritability of lameness in three-year-old standardbred trotters and finds some significant correlation. Two metrics were used to measure lameness, and estimated heritability ranged from 0.25 to 0.33, depending on the metric.

Study Overview

• The study was conducted on 265 randomly selected three-year-old standardbred trotters.
• The aim of the research was to estimate the heritability of lameness in these horses. Lameness can severely affect a horse’s quality of life, performance, and longevity.

Methodology

• Lameness in the horses was assessed on a fixed point scale from 0 to 5, with 0 indicating soundness and 5 indicating that the animal was not weightbearing.
• Two variables were used to describe the signs of lameness. The first, a continuous variable, was created from the sum of the initial lameness score and the lameness scores after separate flexion tests of the carpal, stifle/tarsal, and phalangeal joints. The second, a bivariate variable, was the ratio of lame/sound horses.

Results

• The mean heritability of the continuous variable was estimated to be 0.25, with a standard deviation of 0.21. This result was statistically significant with a determination coefficient of R2 = 0.14. This means that about 14% of the total variation in lameness could be accounted for by heritable factors.
• For the bivariate variable (lame/sound), the estimated heritability was higher at 0.33.
• The researchers used these estimates to calculate breeding values for the 16 sires included in their analysis. These values ranged from 72.2 to 130.5.
• The study did not find a significant influence of gender on the prevalence of lameness.

Implications

• This study suggests that there is a heritable component to lameness in standardbred trotters. Thus, breeding strategies could consider this trait to potentially reduce the prevalence of lameness in future generations.
• The absence of a gender effect on lameness prevalence means that both male and female horses should be equally considered when thinking about these breeding strategies.