Sodium Retention in Large Herbivores: Physiological Insights and Zoogeochemical Consequences

作者：Andrew J. Abraham, Ethan S. Duvall, Christopher E. Doughty, Barbara Riond, Sylvia Ortmann, Melissa Terranova, Elizabeth le Roux, Marcus Clauß · 发表于：Journal of Experimental Zoology Part A Ecological and Integrative Physiology · 年份：2025 · DOI：10.1002/jez.2924 · 被引用次数：4 · 研究领域：Wildlife Ecology and Conservation、Animal Behavior and Welfare Studies、Effects of Environmental Stressors on Livestock

The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excretion by urine occurred approximately twice as fast as excretion by feces, yet both were shorter than indigestible particle markers. These differences correspond to rapid absorption of Na in the upper gastrointestinal tract and transport by blood to the kidneys (urine Na excretion) or resecretion of Na into the lower intestinal tract (fecal Na excretion). Interestingly, for cows, we found a second peak of Na excretion in urine and feces > 96 h after dosage. This result may indicate that surplus Na can be rapidly absorbed and stored in specific body cells (e.g., skin), from which it is later released. Using a propagule dispersal model, we found that the distance of cattle- and horse-driven nutrient dispersal by urine was 31% and 36% less than the fecal pathway and 60% and 41% less than the particle marker pathway, which is commonly used to estimate nutrient dispersal. Future physiological an...