Kaler J, Green L E
Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK.
BMC Vet Res. 2008 Oct 14;4:41. doi: 10.1186/1746-6148-4-41.
Epidemiological studies have used farmer estimates of the prevalence of lameness in their flocks. This assumes that farmers can identify lame sheep. Eight movie clips of sheep with locomotion from sound to moderately lame were used to investigate the ability of farmers and sheep specialists to recognise lame sheep. Each participant was asked to complete a form and indicate, for each movie clip, whether they thought the sheep was lame and whether they would catch it if it was the only lame sheep or if 2 - 5, 6 - 10 or > 10 sheep were equally lame. The farmers' responses were compared with their estimates of flock lameness prevalence and the interval between observing a lame sheep and catching it.
178 farmers and 54 sheep specialists participated. Participants could identify even mildly lame sheep but made a separate decision on whether to catch them. This decision was dependent on the severity of lameness and the number of sheep lame in a group. Those who said they would catch the first lame sheep in a group were significantly more likely to catch mildly lame sheep (farmer-reported median prevalence of lameness 5% (IQR: 2%-6%)). In contrast, farmers who waited for several sheep to be lame indicated that they would only catch more severely lame sheep (farmer reported median flock lameness 11% (IQR: 9%-15%)). Approximately 15% of farmers did not catch individual lame sheep (farmer reported median flock lameness 15% (IQR: 10%-15%)). The flock prevalence of lameness increased as time to treatment increased and time to treatment was positively correlated with only catching more severely lame sheep.
If movie-clips are similar to the flock situation, farmers and specialists can recognise even mildly lame sheep but vary in their management from prompt treatment of the first lame sheep in a group to no individual sheep treatments. The former practices would be appropriate to minimise transmission of footrot, a common, infectious cause of lameness and so reduce its incidence. The analysis also suggests that farmers estimate lameness prevalence relatively accurately because farmers who treated the first mildly lame sheep in a group also reported the lowest prevalence of lameness in their flock.
流行病学研究采用农民对其羊群中跛足患病率的估计。这假定农民能够识别跛足绵羊。使用八个从健康到中度跛足的绵羊运动视频片段，来调查农民和绵羊专家识别跛足绵羊的能力。要求每位参与者填写一份表格，并针对每个视频片段指出他们是否认为绵羊跛足，以及如果这是唯一的跛足绵羊，或者如果有2 - 5只、6 - 10只或超过10只绵羊同样跛足，他们是否会捕捉它。将农民的回答与其对羊群跛足患病率的估计以及观察到跛足绵羊与捕捉它之间的时间间隔进行比较。
178名农民和54名绵羊专家参与了研究。参与者能够识别即使是轻度跛足的绵羊，但对于是否捕捉它们会做出不同的决定。这个决定取决于跛足的严重程度以及一群中跛足绵羊的数量。那些表示会捕捉一群中第一只跛足绵羊的人，显著更有可能捕捉轻度跛足的绵羊（农民报告的跛足患病率中位数为5%（四分位间距：2% - 6%））。相比之下，等待几只绵羊跛足的农民表示他们只会捕捉更严重跛足的绵羊（农民报告的羊群跛足中位数为11%（四分位间距：9% - 15%））。大约15%的农民不会捕捉个体跛足绵羊（农民报告的羊群跛足中位数为15%（四分位间距：10% - 15%））。随着治疗时间的增加，羊群跛足患病率上升，并且治疗时间与只捕捉更严重跛足绵羊呈正相关。
如果视频片段与羊群情况相似，农民和专家能够识别即使是轻度跛足的绵羊，但在管理方式上有所不同，从及时治疗一群中的第一只跛足绵羊到不进行个体绵羊治疗。前一种做法对于将腐蹄病（一种常见的、导致跛足的传染性病因）的传播降至最低并因此降低其发病率是合适的。分析还表明，农民对跛足患病率的估计相对准确，因为在一群中治疗第一只轻度跛足绵羊的农民，其报告的羊群跛足患病率也最低。
