Effect of zinc supplementation on bovine luteal function: In vivo and in vitro findings

Zinc (Zn) is an essential trace element for cellular processes such as oxidative stress regulation. Research on the relationship between Zn and the corpus luteum (CL) is limited, showing contradictory findings. Zinc supplementation before artificial insemination (AI) increases bovine CL size and progesterone (P₄) levels. In mice, in vitro experiments suggest that Zn may reduce P₄ production. This study aimed to evaluate the role of Zn in bovine luteal cell function by assessing 1) the effect of parenteral Zn supplementation (400 mg) 7 days after AI on CL size and plasma P₄ levels in vivo, and 2) the impact of Zn supplementation (0, 0.8 and 1.2 μg/ml) on P₄ production, reactive oxygen species (ROS) levels and luteal cell viability in vitro. In vivo, Zn supplementation increased CL size but reduced plasma P₄ levels. In vitro, 0.8 μg/ml Zn decreased P₄ synthesis and ROS levels while enhancing cell viability, whereas 1.2 μg/ml Zn had no significant effect compared to the control. These findings indicate that Zn modulates luteal function in a dose-dependent manner, reducing oxidative stress while impairing P₄ production. Further studies are needed to optimize Zn supplementation strategies during assisted reproductive technologies and clarify Zn mechanisms of action.