Nano zinc supplementation in broiler nutrition: current evidence, mechanisms of action, and future perspectives.

Zinc is an essential trace mineral involved in numerous biological processes, including growth, antioxidant defense, immune function, and intestinal integrity in broiler chickens. Optimizing its bioavailability remains an important objective in modern poultry nutrition. Nanotechnology has emerged as a promising strategy to enhance zinc bioavailability while potentially reducing dietary inclusion levels and environmental zinc excretion. Current evidence suggests that nano zinc supplementation may enhance antioxidant capacity, modulate immune responses, support intestinal health, and improve productive performance under specific experimental conditions. Several studies further indicate reduced zinc excretion compared with conventional zinc sources, suggesting potential environmental benefits through lower mineral losses. Furthermore, nano zinc has been proposed as part of nutritional strategies aiming to reduce reliance on antimicrobial use by improving gut health and host resilience. However, direct evidence supporting nano zinc as an alternative to antibiotics under commercial production conditions remains limited. Nano zinc supplementation has also been associated with improvements in intestinal morphology, microbial composition, and barrier function, although the underlying molecular mechanisms remain to be fully elucidated. Despite these promising findings, important knowledge gaps remain regarding optimal particle characteristics, dosage, long-term safety, tissue accumulation, and regulatory acceptance. This review summarizes the current evidence on the biological functions and applications of nano zinc in broiler nutrition, discusses the proposed mechanisms of action, critically evaluates the available literature, and highlights priorities for future research.