Production performance and tibia zinc content
were measured. There were no differences in production
performance between the different zinc sources when
fed to broilers until 21 d of age. Tibia zinc content was
increased linearly with the dietary zinc content up to
20 mg/kg zinc sulfate. The relative biological value of
organic zinc was 1.64 compared with zinc sulfate as a
reference zinc source (1.00), as indicated by the slope
ratio of the linear response curves for both zinc sources,
using tibia zinc content as a response parameter. In a
practical European broiler diet, the organic Availa-Zn
had a higher bioavailability than inorganic zinc sulfate.