Estimates of heritability for ossification of the cartilages of the front feet in the Finnhorse.

This research article discusses estimates of the genetic influence (“heritability”) on the ossification (bone formation) of cartilages in the front feet of the Finnhorse breed of horses, and how different ossification parameters are genetically correlated.

Study Objective and Method

• The aim of this research was to estimate heritability for the ossification parameters of cartilages in the front feet of the Finnhorse and also to calculate the genetic correlations between different ossification parameters.
• Data from 964 Finnhorses (age ≥ 2 years; made up of 345 females and 619 males) was analyzed. This included dorsopalmar radiographs of front feet and pedigree information up to four generations.
• Scales from 0-5 were used to grade ossification at the base and the total, with separate ossification centers being observed and noted separately. The researchers controlled for sex-age impacts and used a ‘random animal’ effect model.
• Variance and covariance components were estimated with the Restricted Maximum Likelihood (REML) method assuming an animal model.

Study Findings

• The study found that females had more ossification than males, and this difference increased with age. Additionally, the ossification in medial cartilages progressed noticeably with age in females but not in males. However, increase in ossification was seen in lateral cartilages in both sexes over time. Separate centres of ossification were an incidental finding.
• The estimates of heritability for ossification varied slightly between individual cartilages and between the front feet. For total ossification, the heritability estimates ranged from 0.31 (right lateral) to 0.50 (left medial), and the estimates were slightly higher for ossification at the base of the cartilages.
• Notably, high genetic correlations were found for total ossification between the medial and lateral cartilages within the foot, as well as between parallel ossification parameters between the right and left foot.

Conclusion and Implications

• The study successfully provided heritability estimates which were relatively high. It was concluded that both cartilages, as well as the front feet of Finnhorses, share a similar genetic predisposition to ossify.
• This valuable information can be used in future research assessing other factors contributing to the ossification process. The results can also play a critical role in planning and modifying breeding programmes for this breed of horses, potentially preventing adverse health outcomes related to over-ossification.