Manganese Gluconate as a Safe Trace Element Supplement Enhances Immune Function and Resistance to Staphylococcus aureus Infection in Broilers.

Manganese is an essential trace element with known immunomodulatory properties, yet the effects of organic manganese supplementation on disease resistance in poultry remain poorly understood. This study evaluated the safety and immunoprotective efficacy of orally administered manganese gluconate in yellow-feathered broilers. A total of 120 seven-day-old broilers were randomly allocated to four groups and orally administered either vehicle control or manganese gluconate at 1, 5, or 10 mg/kg body weight for 14 consecutive days. No adverse health responses were observed across all treatment groups, confirming the safety of manganese gluconate within this dosage range. At the optimal dosage, manganese gluconate significantly promoted splenic lymphocyte proliferation (CCK-8 assay), upregulated the expression of key cytokines (IL-2, IL-4, IL-10, TNF-α), improved serum antioxidant status (T-AOC, T-SOD, GSH-PX, MDA), enhanced specific anti-S. aureus IgG production, and strengthened peritoneal macrophage-mediated phagocytosis of S. aureus. Following intraperitoneal challenge with S. aureus Newman strain (1 × 10¹⁰ CFU/bird), manganese gluconate effectively reduced bacterial colonization in the liver, spleen, and kidney, and improved the survival rate of infected broilers. These findings demonstrate that manganese gluconate is a safe and effective nutritional supplement that enhances immune function and increases resistance to bacterial infection in broiler production.