“饲料禁抗”后规模猪场猪传染性胸膜肺炎的血清学调查和分析

Serological Investigation and Analysis of Porcine Contagious Pleuropneumonia in Large-scale Pig Farms after the Ban on Antibiotic Feed Additives

为了解“饲料禁抗”后规模猪场中猪传染性胸膜肺炎放线杆菌(APP)的流行情况,本试验于2021―2023年在16个未免疫疫苗的APP阳性规模猪场采集不同生产阶段猪群的2286份血清样本,应用间接ELISA进行抗体检测。结果显示:(1)16个规模猪场血清样本的APP抗体总阳性率为61.2%(1399/2286),高于文献报道的“饲料禁抗”前猪群阳性率(20%~53%);(2)在不同生产阶段的猪群中,母猪APP抗体阳性率最高(92.4%,545/590),其次为哺乳期仔猪(87.6%,227/259),而后从高到低依次是育肥后期、保育期和育肥中期猪群,APP抗体阳性率分别为63.6%(361/568)、43.7%(129/295)和35.3%(122/346),育肥早期猪群的APP抗体阳性率最低,为6.6%(15/228);(3)初产母猪的APP抗体阳性率(73.8%)明显低于其他胎次母猪(96.3%~97.4%);(4)猪只的APP母源抗体随着日龄的增长而下降,基本在90日龄时降到最低,此后猪群因APP感染而导致APP抗体水平和阳性率均开始缓慢上升,到肥猪出栏前仍一直上升。结果表明,饲养密度增加和推迟肥猪出栏是导致规模猪场APP感染大幅上升的重要因素。

To investigate the prevalence of Actinobacillus pleuropneumoniae(APP)in large-scale pig farms following the background of"Ban on antibiotic feed additives",this study collected 2286 serum samples from different production stages of pig herds in 16 APP-positive large-scale farms that had not been vaccinated against APP between 2021 and 2023.Indirect ELISA was used for antibody detection.The results showed that:(1)The overall APP antibody positivity rate in serum samples from the 16 large-scale farms was 61.2%(1399/2286),higher than the pre-ban positivity rate reported in the literature(20%-53%);(2)Among different production stages,sows had the highest APP antibody positivity rate(92.4%,545/590),followed by nursing piglets(87.6%,227/259).The rates from highest to lowest in other stages were late fattening pigs,nursery pigs,and mid-fattening pigs,with positivity rates of 63.6%(361/568),43.7%(129/295),and 35.3%(122/346)respectively.Early fattening pigs had the lowest APP antibody positivity rate at 6.6%(15/228);(3)The APP antibody positivity rate of gilts(73.8%)was significantly lower than that of multiparous sows(96.3%-97.4%);(4)The maternal APP antibodies in piglets declined with age,reaching their lowest point around 90 days of age.Thereafter,the antibody levels and positivity rates began to rise slowly due to APP infection,continuing to increase until the pigs were slaughtered.The results indicate that increased stocking density and delayed slaughter of fattening pigs are significant factors contributing to the rise in APP infections in large-scale pig farms.