Summary

# Editorial Summary: NAD+ and Sirtuin Activation in Equine Reproduction Decades of selective breeding for athletic performance have inadvertently compromised reproductive efficiency in horses, with mares now entering breeding programmes later in life when oocyte quality has declined. Pollard Charley-Lea's 2024 review synthesises emerging research on nicotinamide adenine dinucleotide (NAD+) and its role in activating Sirtuin proteins, which regulate cellular stress responses and energy metabolism during oocyte maturation and early embryo development—processes particularly vulnerable to age-related decline. NAD+ levels naturally decrease with age, and preliminary evidence suggests that NAD+-elevating interventions (including dietary supplementation and pharmacological agents) may restore Sirtuin function and improve oocyte competence and embryonic viability in mares. Unlike cattle breeding, equine reproduction research remains severely limited by the practical and ethical constraints of mare studies, making in vitro models increasingly valuable for understanding these mechanisms. For breeding programmes seeking to optimise fertility in older mares or maximise embryo production through assisted reproductive technologies, understanding NAD+ metabolism offers a potentially tractable target—though the evidence base remains preliminary and requires rigorous clinical validation before routine application.

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Key Findings

• •Selective breeding for athletic performance has reduced reproductive capability in horses
• •Mare age represents a major barrier to equine reproduction, exacerbated by delayed breeding after racing careers
• •NAD+ and Sirtuin activation show emerging promise in improving oocyte maturation and embryo development
• •NAD+-elevating agents may enhance both in vivo and in vitro equine breeding and embryo production programs

Conditions Studied

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