Abstract: Experiments were conducted to evaluate the effects of lactic acid on the performance, intestinal E.coli and lactobacillus of piglets. 144 Duroc×Landrace×Yorkshire piglets were divided into 3 groups randomly, the control(basal diet), basal+3 g·kg-1 lactic acidifier and basal+6 g·kg-1 lactic acidifier. The growth performance, the number of E. coli and lactobacillus in ileum, caecal and colon contents, the number of lactobacillus adhere to ileum and colon mucosa were determined. The results showed that the average daily weight gain of piglets increased with lactic acidifier supplement; after 14 d, the number of E. coli in ileum, caecal and colon contents decreased; the number of lactobacillus in ileum, caecal and colon contents increased with the lactic acid supplement; the number of lactobacillus adhered to the ileum and colon mucosa increased with the lactic acid supplement. The results suggested the addition of lactic acidifier decreased the intestinal harmful bacteria, increased the probiotics and promoted the growth performance of piglets．

Key words: lactic acid, acidifier, piglet, intestinal microflora