Dr. Chris Cahill reflects on his transformative role in revolutionizing stallion breeding practices at Gainesway, where he helped expand book sizes from the traditional 45 mares to as many as 65-78, dramatically increasing efficiency and profitability. Despite initial skepticism from the industry and insurers, Cahill’s meticulous data tracking and management innovations proved successful, enabling Gainesway to stand more stallions and breed at unprecedented rates. His experiences, including managing a crisis with contagious equine metritis, shaped his pragmatic, business-focused approach to breeding, emphasizing rigorous management and realistic expectations about stallion fertility and mare handling.
However, Cahill now voices concern that the current trend of excessively large book sizes—sometimes exceeding 200 mares—is unsustainable and detrimental to both stallions and the industry’s genetic health. He proposes a “semen cartel” among major farms to cap book sizes around 125 mares and limit registrations to about 100 live foals per stallion, encouraging better management and distribution of mares. This approach aims to reduce veterinary overuse, improve fertility rates, and preserve genetic diversity by discouraging overbreeding of less successful stallions. Cahill calls for industry-wide cooperation to reset breeding practices, warning that without such measures, the gene pool and economic viability of stallion operations will continue to suffer.
