Dietary silica: sources, utilization and animal performance

Although silica (SiO2) is not considered an essential mineral for animals, increasing evidence suggests that it plays important roles in animal production, health and sustainability. However, its functions across species and production systems remain insufficiently consolidated. This review summarizes silica sources, and evaluates its effects on growth, health, reproduction and production performance in livestock, while identifying key knowledge gaps and future research needs. A comprehensive literature review was conducted on silica supplementation in non-ruminants (poultry and pigs) and ruminants and emerging applications, such as silica nanoparticles. Findings were synthesized with respect to bioavailability, physiological effects and production outcomes. Bioavailable forms of silica, particularly orthosilicic acid and diatomaceous earth, show the highest biological efficacy. In non-ruminants, silica supplementation may improve skeletal strength, immune function, oxidative stress resistance, gut microbiota, overall productivity and reproductive performance. In ruminants, silicate clays, such as zeolite and halloysite, may enhance rumen fermentation and milk yield, although excessive intake may impair fiber digestibility or increase the risk of urolithiasis. Silica nanoparticles show promise for improving bioavailability and enabling targeted nutrient delivery. Regulatory agencies, such as the US Food and Drug Administration and European Food Safety Authority, recognize silica as safe at dietary levels of 0.5–2%. However, research remains limited, particularly in ruminants and aquaculture. Overall, silica has potential as a biologically beneficial feed additive for improving animal health, productivity and feed efficiency, although its effects depend on chemical form, dose and species. Its application may contribute to more sustainable animal production by enhancing nutrient utilization efficiency and reducing ammonia emissions. Further research is needed to define species-specific requirements, clarify mechanisms of action and optimize silica delivery systems.