Abstract: An experiment was carried out with a total of 378 22-day-old Arbor Acres commercial male broilers to investigate the effects of intravenously injected Zn source and absorbility level on growth performance and tissue Zn concentration. On 22 d, birds were randomly assigned by bodyweight to one of 9 treatments (Seven pen replicates of six chicks each) in a completely randomized design involving a 4×3 factorial arrangement of treatments. The four Zn sources were Zn sulfate, Zn-AAC with the weak chelation strength, Zn-Pro B with the moderate chelation strength and Zn-Pro A with strong chelation strength, respectively. The three intravenously injected Zn absorbility levels were 0%, 6% and 12%, respectively. All four injected Zn sources shared a control group injected with 0.9% NaCl solution. The birds were injected for 12 days. The results showed that injected Zn source significantly affected (P<0.10) the tibia ash Zn on 6 d after injection. There were no differences (P>0.10) among Zn sources in growth performance during 1 to 6 and 7 to 12 d after injection, pancreas Zn on d 6 after injection, pancreas Zn, and tibia ash Zn on d 12 after injection. Injected Zn absorbility level affected (P<0.10) ADG during d 1 to 6 d, pancreas Zn and tibia ash Zn on d 6 and 12 after injection. No differences were observed (P>0.10) among Zn absorbility level in ADFI during 1 to 6 d or ADFI, ADG and FI during 7 to 12 d after injection. All of the above indices were not affected (P>0.10) by the interaction between Zn source and absorbility level. Chicks injected with solution containing organic Zn source with strong chelation strength had lower (P<0.10) tibia ash Zn concentration than those injected with solution containing organic Zn source with moderate or weak chelation strength, and showed the tendency to be lower (P>0.10) compared with those injected with solution containing inorganic zinc sulfate. The control group had lower (P<0.10) ADG level than the group injected with 6% Zn absorbility solution, and had higher (P<0.10) FI than the group injected with 6% or 12% Zn absorbility solution. There were no differences (P>0.10) among other groups in ADG and FI. Pancreas Zn content and tibia ash Zn content on d 6 and 12 after injection increased linearly (P<0.10) as intravenously injected Zn absorbility level increased. The results indicated that the tibia ash Zn concentration on d 6 after injection was more sensitive for detection of the differences among zinc sources in biological availability. The Zn source with strong chelation strength was the least available for the utilization of tissue in broilers.

Key words: intravenous injection; growth performance; pancreas Zn; tibia ash Zn; broiler