Trace Minerals as Immune Nutritional Adjuvants in Beef Cattle: Metabolic Pathways, Nutritional Immunity and Administration Strategies

Trace minerals are essential cofactors for antioxidant enzymes and immune signaling, yet their status is frequently compromised during stress (weaning, feedlot arrival) due to pre-existing dietary deficiencies, transient reductions in nutrient intake, and acute-phase inflammatory redistribution, increasing bovine respiratory disease (BRD) risk. This critical narrative review integrates the metabolic and immunological pathways of these minerals, highlighting the host’s “nutritional immunity” during acute-phase responses. It contrasts continuous, intake-dependent oral supplementation with rapid, transient injectable routes. Furthermore, it evaluates injectable chemical forms: ethylenediaminetetraacetic acid (EDTA) chelates, upon which most evidence rests, versus gluconates, clarifying that any metabolic advantages of the latter remain strictly hypothetical in the absence of direct comparative cattle trials. While injectables rapidly elevate systemic mineral concentrations, inferences drawn from the synthesized body of evidence indicate that productive and health benefits are inconsistent, primarily favoring high-risk or deficient cattle. Rather than an experimentally validated protocol, the authors propose a theoretical decision model that positions injectable mineral as a targeted “preload” before or during immunological challenges, while oral supplementation serves as the indispensable baseline to maintain reserves. To refine this theoretical approach, further research is needed to address critical knowledge gaps, particularly through efficacy trials that simultaneously evaluate baseline mineral status, immune response, disease incidence, and production performance across different injectable formulations.