Beneficial effects of tetrabasic zinc chloride for weanling piglets and the bioavailability of zinc in tetrabasic form relative to ZnO

An experiment was conducted to compare the efficacy of two Zn sources, zinc oxide (ZnO) and tetrabasic zinc chloride (TBZC) in the diet at pharmacological doses to promote growth of the weanling piglet for 28 days. One hundred and eighty weanling piglets averaged 7.5 kg of body weight (BW) were assigned to six dietary treatments. The six dietary treatments were as following: no supplementation of Zn (control); supplemental Zn at 2250 mg/kg diet from ZnO; supplemental Zn at 3000 mg/kg diet from ZnO; supplemental Zn at 1500 mg/kg diet from TBZC; supplemental Zn at 2250 mg/kg diet from TBZC; and supplemental Zn at 3000 mg/kg diet from TBZC. The results showed that average daily growth (ADG) and average daily feed intake (ADFI) responded quadratically as the dietary supplementation of TBZC or ZnO increased. Feed conversion efficiency responded quadratically in the case of TBZC. Feeding pharmacological Zn from ZnO or TBZC improved growth performance of weanling piglet for the first 4 weeks after weanling. Feeding supplemental Zn from two Zn sources increased plasma and tissue (liver, kidney, and metacarpal) Zn concentrations linearly (P<0.01). Based on plasma Zn concentrations at week 2 or 4 of the experiment, and liver, kidney, metacarpal Zn concentrations at week 4 of the experiment, relative bioavailability (RBV) of Zn in TBZC was 159%, 125%, and 128%, 123%, 122%, respectively, compared to ZnO.