This research investigated how different types of magnesium supplements affect the rumen health and milk production of dairy cows. The findings have potential economic impacts that benefit farmers and the environment.

Rumen homeostasis maintains a stable environment essential for ruminant health, metabolism, and microbial fermentation. Symbiotic anaerobic microbes ferment feed, supplying >70% of energy as volatile fatty acids (VFAs) and up to 90% of amino acid needs via microbial protein (Newbold et al., 2020). Key factors include stable pH (optimal ≥6.2; normal 5.5–6.2), motility, and balanced microbiota. Magnesium is critical: it serves as a cofactor in microbial energy metabolism, supports cellulolytic bacteria, and aids efficient digestion. In adult ruminants, the rumen is the main Mg absorption site, requiring consistent dietary supply since bone reserves are poorly mobilizable. Magnesium also supports parathyroid hormone function to regulate calcium and prevent milk fever. Supplemental Mg sources buffer fermentation acids, helping sustain optimal pH and prevent sub-acute ruminal acidosis (SARA; pH ≤5.8 for ≥3 h) (Nocek et al., 1997), which impairs microbial activity, feed intake, health, and performance. This study evaluates different supplemental Mg sources as buffering agents to maintain rumen homeostasis, mitigate SARA, and improve dairy cow performance.