A total of 180 crossbred pigs (Duroc × Landrace × Large White; BW = 47.1 ± 4.8 kg) were used to investigate the effects of totally replacing inorganic trace minerals (ITMs) by organically bound trace minerals (OTMs) on growth performance, tissue mineral status, liver antioxidant enzyme activities, and fecal mineral excretion in grower-finisher pigs. A randomized complete block design with three treatments and six replicates (n = 10 pigs per pen) was used in this 69-day, 2-phase feeding trial. Experimental treatments were as follows: (1) a basal diet without trace mineral supplementation, (2) basal + ITMs (Fe, Mn, and Zn from sulfates, Cu oxychloride, and sodium selenite providing commercially recommended levels in China at 125, 22.5, 117.5, 30, and 0.3 mg/kg, respectively), and 3) basal + OTMs (Fe, Mn, Zn, and Cu from Bioplex and Se as Sel-Plex (Alltech Inc., Nicholasville, KY) providing levels identical to ITMs). No significant differences (P > 0.05) were observed in ADG, ADFI, or G:F among the treatments during the entire grower-finisher period. Supplementation with minerals, regardless of source, increased (P < 0.05) the Fe, Cu, and Se levels in the plasma; Fe and Zn levels in the liver; and Se levels in heart. Furthermore, compared with ITM group, the concentration of Zn and Se in the liver and heart, and Se in plasma and longissimus muscle were greater (P < 0.05) in OTM group. Hepatic Cu/Zn-SOD and ALP activities were increased (P < 0.05) when either ITMs or OTMs were supplemented. Pigs supplemented with OTMs displayed greater activities of Cu/Zn-SOD, ALP, and GSH-Px in the liver compared to pigs supplemented with ITMs. Dietary mineral supplementation to pig diets greatly increased (P < 0.05) fecal mineral (Fe, Mn, Zn, Cu, and Se) excretion in both grower and finisher phases. Fecal concentrations of Zn, Cu, and Se excretion were lower (P < 0.05) with OTMs supplementation than that in pigs fed diets containing ITMs. These results indicate that use of organic trace minerals, as well as no trace mineral supplementation, did not influence pig growth performance. Totally replacing ITMs by equivalent levels of OTMs could improve hepatic Cu/Zn-SOD, ALP, and GSH-Px activities and reduce fecal Mn, Cu, and Se excretion for grower-finisher pigs when supplemented at commercially recommended levels.

The study was conducted to investigate whether high-dose zinc methionine (Zn-Met) affected the safety of laying hens, including laying performance, hematological parameters, serum chemical parameters, organ index, and histopathology. A total of 540 20-week-old Hy-Line White laying hens was randomly allocated to 6 groups with 6 replicates of 15 birds each. Birds were fed diets supplemented with 0 (control), 70, 140, 350, 700, or 1,400 mg Zn/kg diet as Zn-Met. The experiment lasted for 8 wk after a 2-week acclimation period. Results showed that dietary supplementation with 70 or 140 mg Zn/kg diet as Zn-Met significantly increased average daily egg mass (ADEM), laying rate (LR), and feed conversion ratio (FCR) (P < 0.05) and lowered broken and soft-shelled egg ratio (BSER) (P < 0.05) in comparison with the control group; no significant differences were detected among hens fed with 0, 350, or 700 mg Zn/kg as Zn-Met (P > 0.05); hens administered 1,400 mg Zn/kg showed a significant increase in BSER and remarkable decreases in ADEM, LR, and FCR (P < 0.001). There were no significant differences among hens receiving 0, 70, 140, 350, or 700 mg Zn/kg as Zn-Met in serum chemical parameters (P > 0.05); supplementation with 1,400 mg Zn/kg as Zn-Met remarkably elevated the concentrations of serum total bilirubin (TBILI), glucose (GLU), uric acid (UA), and creatinine (CRE) (P < 0.001), and enhanced activities of serum glutamic oxalacetic transaminase (GOP) and alkaline phosphatase (AKP) (P < 0.001) compared with the control group. No significant histopathological changes were found in hens administered 0, 70, 140, 350, or 700 mg Zn/kg as Zn-Met, while significant histological lesions were observed in the heart, liver, lung, and kidney tissues of hens receiving 1,400 mg Zn/kg as Zn-Met. No significant differences were detected in hematological parameters or organ index (P > 0.05). In conclusion, a nominal Zn concentration of 700 mg/kg as Zn-Met is considered to be no-observed-adverse-effect level following daily administration to hens for 56 days.

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