With the benefits on absorption rate, growth, immunity and environment, iron amino acid chelate has been paid more attention in animal nutrition. Studies showed that chelated or proteinated sources of Fe have 125-185% relative availability compared with ferrous sulfate. The better bioavailability of iron amino acid chelate is maybe mainly due to its highly efficient absorption, but its absorption mechanism is still not clear. Iron glycine chelate (Fe-Gly) could be more easily absorbed compared with o...