Abstract: [Objective] Differences in Mn metabolic utilization between organic and inorganic Mn sources or among organic Mn sources for broilers were detect. [Method] Broilers on 22 day-old were randomly allotted to one of five treatments and injected with 0.9% NaCl solution (Control), or the 0.9% NaCl solution dissolved with Mn sulfate, or organic Mn source with weak, moderate, or strong chelation stength for 20 days. [Result] On d 10 and 20 after injection, chicks injected with Mn containing solution had a significantly higher metatarsal bone ash Mn content, heart Mn content, heart MnSOD activity, and MnSOD mRNA level than those in control group (P < 0.03), but the indices except MnSOD mRNA level could not consistently detect the differences among Mn sources. Chicks injected with solution containing organic Mn sources with moderate chelation strength had higher heart MnSOD mRNA level than those injected with Mn sulfate (P < 0.01) and organic Mn sources with strong chelation strength (P<0.09), and chicks injected with solution containing organic Mn sources with weak chelation strength had higher heart MnSOD mRNA level than those injected with Mn sulfate (P < 0.06). [Conclusion] The results indicated that intravenously injected Mn could significantly affect heart MnSOD gene expression trancriptionally, and this functional index could more rapidly, sensitively and consistently detect the difference among Mn sources than other indices. Intravenously injected Mn from the organic Mn source with moderate and weak chelation strength was utilized and functioned in the sensitive target tissue of broilers more effectively than Mn from Mn sulfate, and the organic Mn source with the strong complex strength would be not good for tissue utilization.