Abstract: In order to study the helminth infection intensity of large-scale pig farms in Jiangsu province,937 fecal samples were collected randomly from 12 large-scale pig farms in Xuzhou,Taizhou,Suqian,Yancheng,Yangzhou and Nantong.The samples were examined by centrifugalization,saturated sodium chloride floatation method and saturated magnesium sulfate floatation method.The results showed that parasite infection was found in all 12 farms.The detection rate of worm eggs in fecal samples was 7.6%.Two farms in Xuzhou had the highest infection rate (20.7%),while two farms in Taizhou had the lowest infection rate (1.7%).The infection rates of pig farms in Suqian,Yancheng,Yangzhou and Nantong were 6.5%,8.2%,5.4% and 5.4%,respectively.The infection species of helminth which were identificated successfully included Ascaris suum,Trichuris trichinella,Metastrongylus apri,Oesophagostomum and Strongyloides stercoralis.The infection rates of Ascaris lumbricoides and Oesophagostomum were 5.2% and 3.6%,respectively.At the same time,the mixed infection of Ascaris lumbricoides and Trichuris trichinella,Ascaris lumbricoides and Oesophagostomum,Ascaris lumbricoides and Metastrongylus apri.were found in pig farms of Xuzhou,Suqian,Yancheng,Yangzhou and Nantong.The infection rates of intestinal parasites in pregnant sows and lactating sows were significantly higher than the rates of other production stages.The infection rate of piglets was the lowest.The eggs of Trematoda,Cestoidea and Archiacanthocephala were not detected.The results showed that nematode infections were common in large-scale pig farms in Jiangsu province.Ascaris lumbricoides,Trichuris trichinella and Oesophagostomum were the most highly infected species.Regular insecticidal treatment was helpful for the prevention and control of nematode diseases in large-scale pig farms.This study provided a scientific basis for the prevention and control of parasitic diseases in large-scale pig farms at present.

Key words: pig; helminth infection; large-scale pig farms