Scollo Annalisa, Fasso Mattia, Nebbia Patrizia, Mazzoni Claudio, Cossettini Claudia
Department of Veterinary Sciences, University of Torino, Torino, Italy.
Swivet Research sas, Reggio Emilia, Italy.
Front Vet Sci. 2022 Mar 17;9:814862. doi: 10.3389/fvets.2022.814862. eCollection 2022.
Oedema disease (ED) caused by Shiga-toxin-producing in pigs is a serious life-threatening disease, particularly among weaned piglets. When a preventive protocol is adopted in a specific farm, interpretation of effectiveness is often complicated in field conditions due to natural or "common cause" variation. For this reason, in this study a Statistical process control (SPC) approach was used to retrospectively evaluate the application of an ED preventive protocol (lower protein diet, fiber, vaccination at 5 days of age) in an infected commercial piglets' weaning site. The analysis was established over a 9-years period ( = 75 consecutive batches; 1,800 weaners per batch) using mortality for each batch as the key parameter of health and production; the statistics and the control limits (mean ± 3-fold sd; UCL, upper control limit; LCL, lower control limit) were based on data from the first 28 batches (Period 1) before the onset of the first ED clinical signs. The charts allowed the detection of defined out of control batches (i.e., with mortality out of the intervention limits) from batch 29 ongoing, exploring a Period 2 (unstable production and ED clinical signs; 36 batches) and a Period 3 (application of the ED preventive protocol; 11 batches). Mortality evaluation using SPC revealed a production system defined under-control (mean moving range bar = 1,34%; UCL = 4,37%; LCL = 0%) during Period 1. During Period 2, charts lost the state of statistical control, as showed by several signals of special cause variation due to the ED outbreak. Period 3 was characterized again by a state of statistical control, where no signals of special cause variation was showed. In conclusion, the retrospective application of SPC charts in the present study was able to confirm the efficacy of an ED preventive protocol in reducing mortality in a piglets' weaning site. SPC charting is suggested as an useful tool to provide insights into relationships between health, managerial, and welfare decision and some selected iceberg parameters in livestock.
猪水肿病（ED）是由产志贺毒素的大肠杆菌引起的一种严重的、危及生命的疾病，尤其是在断奶仔猪中。当在特定猪场采用预防方案时，由于自然或“常见原因”变异，在现场条件下对有效性的解释往往很复杂。因此，在本研究中，采用统计过程控制（SPC）方法回顾性评估一种ED预防方案（低蛋白日粮、纤维、5日龄时接种疫苗）在一个受感染的商业仔猪断奶场的应用情况。分析基于9年期间（=75个连续批次；每批1800头断奶仔猪）的数据，将每批的死亡率作为健康和生产的关键参数；统计数据和控制限（均值±3倍标准差；UCL，上控制限；LCL，下控制限）基于第一批ED临床症状出现前的前28批（第1阶段）的数据。这些图表能够检测出从第29批开始的明确失控批次（即死亡率超出干预限值），研究了第2阶段（生产不稳定和出现ED临床症状；36批）和第3阶段（应用ED预防方案；11批）。使用SPC进行的死亡率评估显示，在第1阶段生产系统处于受控状态（平均移动极差bar = 1.34%；UCL = 4.37%；LCL = 0%）。在第2阶段，图表失去了统计控制状态，如ED爆发导致的几个特殊原因变异信号所示。第3阶段再次以统计控制状态为特征，未显示特殊原因变异信号。总之，本研究中SPC图表的回顾性应用能够证实一种ED预防方案在降低仔猪断奶场死亡率方面的有效性。建议将SPC图表作为一种有用的工具，以深入了解健康、管理和福利决策与家畜中一些选定的冰山参数之间的关系。
