Selenium review sharpens focus on antioxidant support in livestock

CURRENT BRIEF VERSION: A new review in Animals pulls together the current evidence on selenium’s role in the antioxidant systems of cattle, pigs, sheep, and goats, arguing that the trace mineral remains central to immune function, reproduction, stress resilience, and productivity during periods of high metabolic demand. The paper highlights selenium’s biological role through selenoproteins such as glutathione peroxidases and thioredoxin reductases, and it emphasizes that both deficiency and oversupplementation carry consequences. In the U.S., selenium use in complete feed for cattle, swine, and sheep is regulated at levels not to exceed 0.3 ppm, underscoring how narrow the margin can be between nutritional support and excess. (law.cornell.edu)

Why it matters: For veterinary professionals, the review is a useful reminder that selenium status still deserves attention in herd health planning, especially in transition dairy cattle, fast-growing pigs, and young small ruminants in low-selenium regions. Selenium deficiency is classically linked with white muscle disease in ruminants and can contribute to disorders such as mulberry heart disease in pigs, while newer literature continues to connect selenium nutrition with oxidative stress, immune response, and reproductive performance. That reproductive angle is showing up beyond traditional feed supplementation: a recent poultry study found that adding selenium methionine to rooster semen extender improved motility, viability, membrane integrity, and apoptotic markers during short-term liquid storage, with the best results at the lowest tested dose, reinforcing that selenium’s effects can be source- and dose-dependent rather than simply “more is better.” The review also points to a practical challenge vets know well: response depends on species, production stage, selenium source, background diet, and geography, so blanket supplementation strategies can miss the mark. (merckvetmanual.com)

What to watch: Expect more discussion around source selection, targeted supplementation, and how veterinarians can balance antioxidant support with regulatory limits and toxicity risk. Emerging work on dose-responsive effects in reproductive tissues and biologic preservation may further push selenium conversations toward precision use rather than routine escalation. (law.cornell.edu)