Fertility Decline in Breeding Stallions
This retrospective study examined the etiological factors contributing to fertility decline in breeding stallions and assessed reproductive outcomes following treatment, with the goal of informing improved breeding management strategies.
Study Design:
- 43 stallions, ages 9–25 years, referred to clinic between 2016–2023
- Cases classified into etiological groups: age-related decline (n=1), testicular/epididymal issues (n=5), infections (n=4), endocrine dysfunction (n=1), semen quality issues (n=3), poor management/nutrition (n=16), environmental/seasonal factors (n=7), trauma or injury (n=3), psychological factors (n=3)
- Data sourced from breeding records and veterinary evaluations; statistically analyzed
Key Findings:
- Reproductive mismanagement was the leading cause of fertility decline at 48%, including anabolic steroid use
- Pathology of reproductive organs (infectious and non-infectious) accounted for 25%
- Behavioral factors contributed 20%
- Endocrine disorders represented 7% (all p<0.05)
- Significant correlations identified between suboptimal management practices and declining fertility rates
- Nutritional deficits and seasonal variation were confirmed as additional influencing factors
Conclusions:
- The majority of stallion fertility decline is attributable to preventable management failures rather than primary pathological conditions
- Enhanced breeding management protocols, routine health monitoring, and avoidance of anabolic steroid use are identified as the most impactful corrective strategies
- A deeper understanding of stallion reproductive physiology is essential for optimizing long-term breeding career outcomes
(Farnia H, Bencharif D, Bruyas JF. 2025. Unveiling fertility decline in stallions: causes and outcomes. JEVS 145:105281 – Presented in Association with and by Permission of the International Society for Equine Reproduction)
