This study aimed to investigate the effects of various organic sources of zinc at different levels on growth performance, physiological indices, antioxidant status, immunity, and mineral metabolism in broiler chickens. A total of 1,400 one-day-old male chicks were used in a completely randomized design with 10 experimental treatments, each arranged in 5 replicate pens with 28 birds per pen. The treatments included a control diet containing zinc sulfate (ZnSO₄); zinc–methionine supplementation at levels of 40, 80, and 120 mg/kg diet (Zn-Met40, Zn-Met80, and Zn-Met120); zinc–glycine supplementation at similar levels (Zn-Gly40, Zn-Gly80, and Zn-Gly120); and advanced zinc chelate supplementation at corresponding levels (Zn-ACT40, Zn-ACT80, and Zn-ACT120). The results showed that the Zn-ACT80, Zn-ACT120, and Zn-Met80 treatments significantly increased body weight gain, improved feed conversion ratio, and increased performance index compared with the control and Zn-Gly40 treatments (P < 0.05). The Zn-ACT80, Zn-ACT120, Zn-Met80, and Zn-Met120 treatments significantly increased the activity of antioxidant enzymes, including superoxide dismutase and catalase, and increased total serum antioxidant capacity (P < 0.05). Improvements in nutrient absorption and ileal digestion of crude protein were also observed in these treatments. The Zn-ACT80 and Zn-Met120 treatments further increased zinc concentrations in the bone and pancreas and decreased zinc excretion through feces (P < 0.05), indicating higher bioavailability than Zn-Gly at comparable levels. An increase in the number of goblet cells and an improvement in the absorptive surface of the intestinal villi were also reported in the Zn-ACT80 and Zn-Met80 treatments (P < 0.05). From an economic point of view, Zn-ACT80 achieved effectiveness equivalent to, or greater than, that of Zn-ACT120 in many indices. In conclusion, the findings showed that the advanced zinc chelate was comparable to zinc–methionine in terms of bioavailability and effectiveness in improving the performance and health of broilers, and both supplements were superior to zinc–glycine, suggesting the use of advanced zinc chelate as a new and effective source of zinc in poultry diets.
