Abstract: Seventy-two crossbreed weaned piglets of 35 days were selected and divided into eight groups at random, third in each group with third replications. Each group received one treatment randomly. The eight treatments include two controls and six special treatments. The results showed that ①adding high copper and citric-acid in the basic diet can increase daily gain, ratio of diet gain to dry matter, and decrease the incidence of diarrhea compared to the two controls groups. ②adding copper and citric-acid can help the metabolization and absorption of high copper, and result a good ecological effects. ③Generally, it is no obvious effects on the blood and biochemical indicators by adding various high copper and citric-acid, and the value of different indicators changes in a normal ranges. ④The interaction between high copper and citric-acid exists, the combination of 150 mg/kg high copper and 1.5% citricacid has the best effect on the performance traits of weaning piglets. 

Key words: weaning piglets; copper above nutrient requirement level; citric-acid; performance trait; blood and biochemical indicator