The improved absorption of Zn that was observed for Zn(HMTBa)2 compared with ZnSO4 resulted in increased
ATTD of Zn in the pigs fed corn–SBM diets.These results are consistent with data by Burkett et al.2009), who also reported a greater ATTD for Zn chelated with small peptides compared with ZnO and ZnSO4. A possible reason for this observation is that Zn(HMTBa)2 is more stable in the upper gastrointestinal tract, which may minimize the formation of the complex between Zn and phytic acid and allow Zn(HMTBa)2 to be delivered to the absorptive cells in the jejunum and ileum and, therefore, increase Zn absorption (Leeson and Summers,2001; Yi et al., 2007; Richards et al., 2010). The observation that no differences were observed in the absorption and ATTD of Zn between Zn(HMTBa)2 and ZnSO4 if
pigs were fed the low-phytate corn grits diets further indicates that it may be the phytate in the corn–SBM diet
that results in the reduced absorption of Zn from ZnSO4.