The effect of gilt flow management during acclimation on <em>Mycoplasma hyopneumoniae</em> detection

The objective of this study was to characterize the Mycoplasma hyopneumoniae (M. hyopneumoniae) detection and seroconversion patterns in recently acclimated gilts to be introduced to endemically infected farms using different types of replacement management. Three gilt developing units (GDUs) belonging to sow farms were included in this investigation: two farms managed gilts in continuous flow, and one farm managed gilts all-in/all-out. Two replicates of 35 gilts each were selected per GDU and sampled approximately every 60 days for a total of four or five samplings, per replicate and per GDU. Detection of M. hyopneumoniae was evaluated by PCR, while antibodies were measured using a commercial ELISA assay. Also, M. hyopneumoniae genetic variability was evaluated using Multiple-Locus Variable number tandem repeat Analysis. Detection of M. hyopneumoniae was similar across GDUs. Although a significant proportion of gilts was detected positive for M. hyopneumoniae after acclimation, an average of 30.3 % of gilts was negative at any point during the study. Detection of M. hyopneumoniae antibodies was similar among GDUs regardless of flow type or vaccination protocol. The genetic variability analysis revealed a limited number of M. hyopneumoniae types within each GDU. Results of this study showed a similar pattern of M. hyopneumoniae detection by PCR and seroconversion by ELISA among GDUs, regardless of the type of flow management strategies applied to gilts.

本研究的目的是描述在采用不同类型的后备母猪管理方式下，即将引入地方流行性感染猪场的新适应后备母猪中猪肺炎支原体（M. hyopneumoniae）的检测情况和血清转化模式。本研究纳入了属于母猪场的三个后备母猪培育单元（GDUs）：两个猪场采用连续流动方式管理后备母猪，一个猪场采用全进全出方式管理。从每个培育单元中选取两组，每组35头后备母猪，大约每60天采样一次，每个培育单元每组共采样4次或5次。通过聚合酶链反应（PCR）评估猪肺炎支原体的检测情况，同时使用商业酶联免疫吸附测定（ELISA）检测抗体。此外，使用多位点可变数目串联重复序列分析评估猪肺炎支原体的基因变异性。不同培育单元之间猪肺炎支原体的检测情况相似。尽管在适应后有相当比例的后备母猪被检测出猪肺炎支原体呈阳性，但在研究期间的任何时间点，平均有30.3%的后备母猪呈阴性。不同培育单元之间猪肺炎支原体抗体的检测情况相似，与流动类型或疫苗接种方案无关。基因变异性分析显示每个培育单元内猪肺炎支原体的类型数量有限。本研究结果表明，不同培育单元之间通过PCR检测猪肺炎支原体以及通过ELISA检测血清转化的模式相似，与应用于后备母猪的流动管理策略类型无关。