EFFECTIVENESS OF A ZINC AMINO-ACID CHELATE AND ZINC-SULFATE IN RESTORING SERUM AND SOFT-TISSUE ZINC CONCENTRATIONS WHEN FED TO ZINC-DEPLETED PIGS

In a 36-d experiment, 32 pigs were depleted of Zn (24 d) using a soy-i solate (basal) diet (17 mg/kg of Zn) and then fed the basal diet (12 d ) supplemented with 45 mg/kg of Zn from ZnSO4 (purified zinc sulfate d ry powder, ZnSO4 . nH(2)O) or from a Zn amino acid chelate (ZnAAC) to study the effectiveness of these dietary Zn sources in restoring serum and soft tissue Zn concentrations. Concurrently, nondepleted pigs wer e pair-fed both Zn-supplemented diets (eight pigs per diet) throughout the experiment. Serum Zn concentrations and serum alkaline phosphatas e (ALP) activity of pigs fed the diets with no supplemental Zn were lo wer (P < .05) than those of nondepleted pigs after 7 and 14 d, respect ively. After 24 d, concentrations of Zn in liver, pancreas, kidney, br ain, and small intestine of Zn-depleted pigs were lower (P < .01) than those of nondepleted pigs. Except for decreased (P < .001) kidney Cu, soft tissue Cu and Fe concentrations were not affected by Zn status o r Zn source. From d 24 to 36 (Zn repletion), serum and tissue Zn conce ntrations and serum ALP activities increased (P < .05), but the respon se was similar for both Zn sources in Zn-depleted and nondepleted pigs . At d 30 and 36, kidney Cu was increased (P < .01) in Zn-depleted pig s fed 45 mg/kg of Zn as either ZnSO4 or ZnAAC. Furthermore, Fe concent ration was higher (P < .05) in intestinal segments of Zn-depleted and nondepleted pigs fed ZnAAC than in pigs fed ZnSO4. Accumulations of Cu in the kidney and Fe in the small intestine were affected by depletio n and repletion of Zn and by dietary Zn source, respectively. In concl usion, serum and soft tissue Zn concentrations were clearly affected b y Zn status; however, an effect of Zn source was not observed.