Abstract: 【Objective】 This experiment was conducted to determine the required level of zinc in goose feed. The effects of different levels of dietary zinc on immunity, antioxidant capacity and metallothionein (MT-I) mRNA gene expression to 5-15-week-old Qing-Nong-Hui geese were evaluated. 【Method】 Three hundred and sixty 29-day-old Qing-Nong-Hui geese were randomly selected and divided into six treatment groups with six replicates for each group, and each replicate contained ten geese (5♂+5♀). The content of added dietary zinc in each group was 27.46 (GroupⅠ, control), 77.46 (GroupⅡ), 127.46 (Group Ⅲ), 177.46 (Group Ⅳ), 227.46 (Group Ⅴ), and 277.46 (Group Ⅵ) mg·kg^-1, respectively. The geese were fed for 11 weeks. 【Result】The results were as follows: Index of thymus, spleen and bursa of fabricius showed an increase and downward trend with the effect of zinc level in feed. The thymus index obtained the highest (P＜0.05) level when the added zinc in feed was 127.46 mg·kg^-1, while the spleen index and the fabricius bursa index reached the highest level (P＜0.05) when the added zinc in feed was 77.46 mg·kg^-1. The index of immune organs decreased as long as the dietary zinc in feed was out of the range of 77.46-127.46 mg·kg^-1. The antibody titer reached the highest (P＜0.05) after the geese were immunized by goose paramyxovirus vaccine for 14 days when the zinc level in feed was 157.41 mg·kg^-1. The activity level of total antioxidant capacity (T-AOC) for the goose serum and liver reached the highest (P＜0.01) when the zinc level in feed was 153.84 mg·kg^-1. The activity level of both catalase (CAT) and glutathione peroxidase (GSH-Px) for the serum and liver of goose was the highest (P＜0.01) when the zinc level in feed was 148.33 mg·kg^-1. The activity level of superoxide dismutase (CuZn-SOD) was the highest (P＜0.01) in the goose’s serum and liver when the zinc level in feed was 148.33 mg·kg^-1. On the other hand, when the zinc level in feed was 177.46 mg·kg^-1, the malonaldehyde (MDA) in the serum and liver had the lowest level (P＜0.05); With the increase of the zinc level in feed, the expression quantity of MT-I mRNA was significantly increased (P＜0.05). And when the zinc level in the feed was 177.46 mg·kg^-1, the expression quantity of MT-I mRNA of liver was the highest. It was highly significant that the expression quantity of MT-I mRNA in goose liver was positively correlated with the activity level of T-AOC (r= 0.94, P＜0.01) and CuZn-SOD (r= 0.97, P＜0.01). The MT-I mRNA expression level in goose liver was also positively correlated with the activity level of CAT (r=0.85, P＜0.05), GSH-Px (r=0.89, P＜0.05), and negatively correlated with MDA (r=-0.70, P＞0.05). The expression level of MT-I mRNA in goose liver was significantly positively correlated with activity levels of T-AOC (r=0.99, P＜0.01), CAT (r=0.92, P＜0.01) and CuZn-SOD (r=0.94, P＜0.01) in serum. It was also positively correlated with GSH-Px (r=0.81, P＞0.05) and negatively correlated with MDA (r=-0.39, P＞0.05).【Conclusion】 Appropriate additional level of dietary zinc promoted the immune organs development and antioxidant capacity of goose. Dietary zinc also intervened the MT-I mRNA expression level, which was closely related with the body’s antioxidant capacity. Feed zinc levels in the 77-150 mg·kg^-1 range can keep the body in high immunity and antioxidant capacity level of the 5-15 weeks old geese.

Key words: zinc, geese, immune, antioxidant capacity, MT-I mRNA gene, correlation analysis