Abstract: In order to provide evidence for precise prevention and control of Porcine proliferative enteropathy， the prevalence of Lawson Intracellularis in large?scale pig farms under the background of antibiotic?free feed and restricting the use of antibiotics in pig breeding industry was investigated. In this study，nested PCR and indirectELISA were used to detect fecal and serum samples from different pig farms. Under the background of antibiotic?free feed，nested PCR detection was conducted on 695 fecal samples collected from different pig farms. the overall infection rate was 23.88%. The infection rates of nursery pigs，finishing pigs and boars were 16.56%，29.58% and 24.63%，respectively. The results of the follow?up survey of the pig herds with antibiotic?free feed and under the background of restricting the use of antibiotics in pig breeding industry were as follows：the infection rate of nursery pigs at 30，44，58 and 72 days of age was 16.67%，20.00%，50.00% and 70.00%，respectively. The infection rate of gilts ranged from 44.44% to 66.67%. As for the ELISA test results，the positive rate of lawsonia intracellularis was 42.6% in 338 serum samples and the positive rate of Lawsonia Intracellularis range from 10% to 75.90% in pig farms from different provinces. The aboved results showed that the prevalence of Lawsonia Intracellulare in large?scale pig farms in China were at a high level at present. The highest infection rates of nursery pigs and gilts were 70% and 66.67% respectively. The infection rate of nursery pigs increased significantly with the increase of age. Therefore，it is necessary to pay more attention to the prevention and control of porcine proliferative enteropathy in large?scale pig farms under the background of antibiotic?free feed.

Key words: Pigs； Lawsonia Intracellularis； Nested PCR； ELISA； Epidemiology

摘要： 为掌握在饲料禁抗和养殖端限抗背景下规模化猪场胞内劳森菌的流行情况，为猪 增生性肠炎的精准防控提供依据。该研究运用巢式PCR和间接ELISA方法对饲料禁抗后不同 来源的粪便样品和血清样品进行检测。饲料禁抗背景下，对采自不同猪场695 份粪样的巢式 PCR检测显示，猪群胞内劳森菌的总体感染率为23.88%，保育猪、肥育猪和种猪感染率分别为 16.56%、29.58%和24.63%。对饲料禁抗和饲养期间限抗猪群的跟踪调查结果为，保育猪在30、 44、58、72日龄的感染率分别是16.67%、20.00%、50.00%和70.00%；后备母猪的感染率44.44%— 66.67%。对 338 份不同猪场送检血清样品的 ELISA 检测显示，胞内劳森菌的抗体阳性率为 42.6%，不同猪场的阳性率10%—75.90%。上述结果表明，现阶段我国规模化猪场胞内劳森菌 PCR检测阳性率和ELISA检测的阳性率均处于较高水平。饲料禁抗以及饲养期间限抗的保育 猪和后备母猪群跟踪调查的最高感染率分别达70%和66.67%，保育猪随着饲养日龄的增加感 染率呈明显地升高趋势。因此，在饲料禁抗背景下，规模化猪场应更加重视猪增生性肠炎的 防控。

关键词: 猪；胞内劳森菌； 巢式PCR； ELISA； 流行病学