Abstract: To study the effect of high zinc diet long-term exposure on growth performance and serum biochemical indexes, sixty “Duroc×Landrace×Yorkshire” crossbred weanling piglets (23 ±1 days of age) were randomly divided into 3 groups with 20 piglets each by weight and sex, fed with basal diet, basal diet plus 3000 mg/kg zinc (from ZnO), and basal diet plus 500 mg/kg zinc (from ZnMet), respectively. Blood samples in 10 piglets from each group were taken on 0，21，42，70 d after weaning for measuring serum biochemical indexes. The results showed that high zinc diets increased significantly (P<0.05 or P<0.01) absolute weigh(AW) and average daily gain(ADG) of weanling stress piglets on 0~42 d postweaning, and dreased significantly (P<0.05) the average daily gain on 42~70 postweaning. The serum AST and ALT levels were significantly (P<0.05 or P<0.01) higher in piglets of treating group than that in piglets of control group on 42~70 postweaning , and the serum TP and ALB levels were significantly (P<0.05 or P<0.01) lower. High zinc diets increased significantly (P<0.01) ALP levels of weanling stress piglets on 21~70 d postweaning. The results indicated that feeding high zinc diets can remarkably degrade weanling piglets stress on the earlier period, but high-zinc diet longterm exposure to weanling piglets caused poisoning response.

Key words: high zinc diets; long-term exposure; weanling piglets; growth performance; serum biochemical indexes