Impact of health disorders and culling reasons on functional and biological longevity in Warmblood breeding stallions.

This research paper investigates the effects of health conditions and reasons for retiring (culling) on the service length (functional longevity) and lifespan (biological longevity) of breeding stallions. The researchers used data from 455 warmblood stallions in Germany from 1975 to 2010. Different factors such as infectious diseases had variable impacts on the horses’ functional longevity. The stallions’ specific traits, performance, and stud fees also influenced their longevity.

Methodology of the Research

• The researchers collected complete breeding data from 455 warmblood stallions that served between 1975 and 2010 at the Marbach State Stud in Germany.
• They conducted a semi-parametric survival analysis to examine the stallions’ functional and biological longevity. The analysis took into account competing risks to create hazard ratios (HRs) which measure the risk of event occurrence (like termination of functional life in this study).

Key Findings

• The average lifespan (18.0 years) of the examined stallions was twice as long as their average service period (9.0 years).
• Both the lifespan and the service period significantly increased over the three decades spanning from the 1970s to the 1990s.
• Infections and dissatisfaction with performance had the highest hazard ratios, which means they were the leading causes for ending a stallion’s service (functional life).
• On the other hand, disorders of the cardiovascular system had the lowest hazard ratio, making them the least likely cause for termination of service.
• Factors relating to demand for stallions (like coat color and performance in dressage and show-jumping) had a significant impact on functional longevity but not on biological longevity.
• Higher stud fees were associated with lower hazard ratios, indicating that they contributed to greater functional and biological longevity.

Implications

• This research provides vital insights into the factors influencing the service length and lifespan of warmblood breeding stallions.
• The findings could help in improving breeding programs by identifying areas to focus on for enhancing the functional and biological longevity of the stallions, which could consequently enhance their welfare.
• Understanding the influence of factors such as genetic merit, performance, and stud fees could guide decision-making in both breeding and purchasing stallions.