UCD Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Ireland.
UCD Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Ireland.
Prev Vet Med. 2020 Oct;183:105095. doi: 10.1016/j.prevetmed.2020.105095. Epub 2020 Aug 17.
Our aim was to examine, for the first time, the spatial and network characteristics of cattle movements between herds in the Republic of Ireland (ROI), to inform policy and research of relevance to the surveillance and management of disease in Irish cattle. We analysed movements in 2016 as discrete herd to herd pairings (degree), herd to herd pairings by date of move (contacts) and herd to herd pairings by date and individual animal (transfers), and looked at each of these as movements out of a herd (out degree, out contacts, out transfers) and into a herd (in degree, in contacts, in transfers). We found that the frequency distributions, by herd, of these six move types were all heavily right skewed but in the case of the 'out' data types more closely followed a log-normal than the scale free distribution often reported for livestock movement data. For each distinct herd to herd contact in a given direction, over 90 % occurred only once, whereas the maximum number of occurrences was 62. Herd-level Spearman rank correlations between inward moves (represented as in degree, in contacts, in transfers) and outward moves (out degree, out contacts, out transfers) were weak or even negative whereas correlations between different measures of outward moves or inward moves (e.g. out degree vs. out contacts, in transfers vs. in degree) were stronger. Correlations between these variables and the network measure betweenness varied between r = 0.513 and r = 0.587. Some herds took part in a relatively large number of movements whilst also retaining their cattle for long periods (> 100 days) between moves. In and out degree, contacts and transfers were mapped across Ireland on a 5 km grid, and additionally normalized per 1000 animals and per herd. We found considerable variation in the number of movements by county. Approximately half of transfers were conducted within a single county, but the number and distance of between county movements varied considerably by county of origin and county of destination, with the proportion of moves completed within a single county correlated with its size. Herds exchanging cattle via a market were generally further apart than when moves were made directly herd to herd. For contacts, the distances moved away from the herd were on average greater for origin herds in the west of ROI whereas distances moved to a herd were generally greater for destination herds in the centre-east and the north-west.
我们的目的是首次检验爱尔兰共和国（ROI）牛群之间的空间和网络特征，为爱尔兰牛群疾病监测和管理的相关政策和研究提供信息。我们分析了 2016 年的离散 herd to herd 配对（度）、按移动日期的 herd to herd 配对（接触）和按日期和个体动物的 herd to herd 配对（转移），并将每一个 herd 作为 herd to herd 的输出（出度、出接触、出转移）和 herd to herd 的输入（入度、入接触、入转移）进行了分析。我们发现，这六种移动类型的 herd 分布都严重右偏，但在“出”数据类型的情况下，更接近对数正态分布，而不是家畜移动数据中经常报告的无标度分布。在给定方向上，每一个独特的 herd to herd 接触中，超过 90%只发生一次，而发生的最大次数为 62 次。在 herd 水平上，内向移动（代表为入度、入接触、入转移）和外向移动（出度、出接触、出转移）之间的 Spearman 等级相关系数较弱，甚至为负，而外向移动或内向移动的不同度量之间的相关性（例如，出度与出接触，入转移与入度）较强。这些变量与网络测度 betweenness 的相关性在 r=0.513 到 r=0.587 之间变化。一些 herd 参与了大量的移动，同时在移动之间也保持了很长时间（超过 100 天）的牛群。在爱尔兰，以 5km 网格的形式对入度、出度、接触和转移进行了映射，并根据每 1000 头动物和每 herd 进行了归一化。我们发现各县之间的移动数量有很大差异。大约一半的转移是在一个单一的县内进行的，但在县与县之间的移动数量和距离因起源县和目的地县而异，完成的移动数量与该县的大小相关。通过市场交换牛群的 herd 通常比直接 herd to herd 的 herd 之间的距离更远。对于接触，起源 herd 来自 ROI 西部的 herd 离开 herd 的平均距离更大，而目的地 herd 到达的距离通常更大，中心-东部和西北部。
