# Injectable Mineral Supplementation During the Transition Period Reduces Uterine Disease and Hypocalcemia and Enhances Humoral Immunity in Holstein Dairy Cows

## TL;DR

Injecting minerals in cows around calving improves uterine health, reduces low calcium, and boosts immunity, potentially enhancing dairy cow welfare.

## Contribution

This study demonstrates that injectable mineral supplementation during the transition period improves immune and uterine health in dairy cows.

## Key findings

- Injectable mineral supplementation reduced hypocalcemia and metritis in Holstein cows.
- Supplemented cows showed improved uterine health and immune status without affecting energy metabolism disorders.
- The benefits were more pronounced in immune competence and oxidative regulation rather than energy balance.

## Abstract

The period around calving is one of the most challenging stages in the life of a dairy cow. Supporting cows during this transition may improve their health and overall performance. This study evaluated whether repeated injections of essential minerals during the transition period could improve health, immune status, and productivity in Holstein cows. The supplementation was associated with improved indicators of uterine health and calcium status, although it had limited effects on classical energy metabolism markers (e.g., NEFA, BHB) or disorders such as mastitis or ketosis. These findings suggest that injectable mineral supplementation may be a useful management strategy to improve health during the transition period, potentially reducing disease risk and supporting animal welfare in dairy herds.

The transition period in dairy cows is marked by metabolic, oxidative, and immune challenges that increase susceptibility to periparturient diseases. Injectable mineral supplementation (IMS) has been proposed to support immunometabolic adaptation by enhancing antioxidant capacity and immune function, with consistent associations with improved health outcomes but variable effects on production. Therefore, this study evaluated the effects of repeated intramuscular multi-mineral supplementation during the transition period on health, metabolic stress, immune status, and productive performance in Holstein cows. Supplementation was associated with lower odds of subclinical hypocalcemia on day 4 postpartum in primiparous cows (p = 0.02) and overall for persistent subclinical hypocalcemia (p = 0.03). Multiparous cows (p = 0.04) and the overall population (p = 0.01) showed consistent effects on metritis following IMS. Supplemented cows had improved metabolic and uterine health indicators without affecting energy metabolism-related disorders. Although no differences were detected for major postpartum health disorders, its main benefits may involve immune competence, oxidative regulation, and physiological resilience rather than energy balance.