Serum and Placental Trace Element Levels, Major Uterine Pathogens, and Reproductive Performance in Simmental Cows During the Early Postpartum Period

This study investigated the associations among serum and placental trace element concentrations, major uterine pathogens isolated from lochia, and reproductive performance during the early postpartum period in cows. Placental samples collected immediately after parturition and blood and lochia samples obtained on days 0, 2, 4, 6, 8, and 10 postpartum from 36 Simmental cows. The primary uterine pathogens identified were Trueperella pyogenes, Escherichia coli, Fusobacterium necrophorum, and Prevotella melaninogenica. Cows with pathogen isolation on consecutive sampling days were classified as infected (IC), whereas cows with no pathogen isolation were classified as non-infected (NIC). Serum Mn, Se, Fe, and Cu concentrations were higher in NIC (P < 0.05, P < 0.01) than those in IC. However, serum Zn level was higher in IC than NIC. No significant group differences were detected in placental element contents. These findings indicate that alterations in trace element status may influence uterine defense mechanisms and subsequently shape postpartum reproductive performance. Regular monitoring of trace element profiles could therefore support the early detection of imbalances and enable timely interventions to reduce uterine infection risk. Future integrative studies evaluating mineral dynamics across serum, placenta, and lochia alongside microbial colonization may improve understanding of postpartum uterine infections and guide herd-level reproductive management strategies to enhance reproductive performance.