Effects of a dietary supplementation with zinc oxide nanoparticles, compared to zinc oxide and zinc methionine, on performance, egg quality, and zinc status of laying hens

An experiment was conducted to investigate the effect of diets supplemented with different Zn sources on performance, egg quality, bone parameters, Zn status, superoxide dismutase (SOD) activity, and egg malondialdehyde (MDA) content in laying hens. A total of 192 laying hens at 52 wk of age, with the initial average body weight of 1.53 +/- 0.02 kg, were randomly assigned to 4 treatments with 4 replicate cages and 12 laying hens per cage. Dietary treatments included the corn-soybean meal based diet (without Zn supplementation), and basal diet supplemented with 80 mg Zn/kg diet from Zn oxide-nanoparticles (ZnO-NP), Zn oxide, and Zn-Met. The results showed that dietary Zn supplementation had no effect on feed intake, feed conversion ratio, live body weight, and egg loss. However, the greatest egg production and egg weight observed in ZnO-NP and Zn-Met treatments respectively (P < 0.05). Laying hens fed diets supplemented with ZnO-NP and Zn-Met had a greater egg mass compared to other treatments (P < 0.05). Overall, Zn supplementation increased egg shell weight and Haugh unit (P < 0.05). Dietary ZnO-NP supplementation increased egg shell thickness and egg shell strength, as compared to control (P < 0.05). The bone breaking strength and ash weight was greater in ZnO-NP and Zn-Met treatments, respectively (P < 0.05). The Zn deposition in tibia, liver, pancreas, and egg was greater in laying hens fed ZnO-NP and Zn-Met (P < 0.01). Plasma Zn status was not influenced by treatments. In treatments supplemented with ZnO-NP and Zn-Met, the SOD in the liver and pancreas were greater than the other treatments (P < 0.01). The MDA content in egg was reduced in treatments supplemented with Zn (P < 0.01). In conclusion, this study has shown that supplementation of a diet with ZnO-NP be a suitable source of zinc for laying hens.