The effect of different dietary zinc sources on mineral deposition and antioxidant indices in rabbit tissues

The purpose of this study was to compare the effect of dietary zinc from inorganic and organic sources on the concentration of Zn, Cu, Mn and Fe in plasma, tissues and faeces of rabbits. Simultaneously, the activities of total superoxide dismutase (SOD), specific Cu/Zn SOD, glutathione peroxidase (GPx), lipid peroxidation and total antioxidant capacity (TAC) in liver and kidney were also determined. Ninety-six 49-day-old broiler rabbits were allocated to 4 dietary treatments, each replicated 6 times with 4 animals per replicate. For the subsequent 6 wk, the rabbits were fed an identical basal diet (BD) supplemented with an equivalent dose of Zn (100 mg/kg) from different sources. Group 1 (control) received the unsupplemented BD, while the BD for groups 2, 3 and 4 was supplemented with Zn from Zn sulphate, Zn chelate of glycine hydrate (Zn-Gly) and Zn chelate of protein hydrolysate (Zn-Pro), respectively. The intake of dietary Zn sulphate resulted in an increase in Zn plasma concentration (1.85 vs. 1.48 mg/L; P<0.05) compared to the control group. Feeding the diets enriched with Zn increased the deposition of Zn in the liver (P<0.05), irrespective of the Zn source. The addition of Zn-Pro resulted in significantly higher Cu uptake in liver (P<0.05) than in the control and Zn sulphate group (56.0 vs. 35.0 and 36.7 mg/kg dry matter (DM), respectively). Neither Mn nor Fe concentration in plasma and tissues were affected by dietary Zn supplementation, with the exception of Fe deposition in muscle, which was significantly decreased (P<0.05) in rabbits supplemented with inorganic Zn sulphate compared to control and Zn-Gly group (9.8 vs. 13.3 and 12.2 mg/kg DM, respectively). Intake of organic Zn-Gly significantly increased the activities of total SOD (43.9 vs. 35.9 U/mg protein; P<0.05) and Cu/Zn SOD (31.1 vs. 23.8 U/mg protein; P<0.01) as well as TAC (37.8 vs. 31.2 μmol/g protein; P