Considering appropriate replication in the design of animal social network studies

© 2019, The Author(s). Social network analysis has increasingly been considered a useful tool to interpret the complexity of animal social relationships. However, group composition can affect the contact structure of the network resulting in variation between networks. Replication in contact network studies is rarely done but enables determination of possible variation in response across networks. Here we explore the importance of between-group variability in social behaviour and the impact of replication on hypothesis testing. We use an exemplar study of social contact data collected from six replicated networks of cattle before and after the application of a social disturbance treatment. In this replicated study, subtle but consistent changes in animal contact patterns were detected after the application of a social disturbance treatment. We then quantify both within- and between-group variation in this study and explore the importance of varying the number of replicates and the number of individuals within each network, on the precision of the differences in treatment effects for the contact behaviour of the resident cattle. The analysis demonstrates that reducing the number of networks observed in the study would reduce the probability of detecting treatment differences for social behaviours even if the total number of animals was kept the same

Agricultural, socioeconomic and environmental variables as risks for human verotoxigenic Escherichia coli (VTEC) infection in Finland

<p>Abstract</p> <p>Background</p> <p>Verotoxigenic <it>E. coli </it>(VTEC) is the cause of severe gastrointestinal infection especially among infants. Between 10 and 20 cases are reported annually to the National Infectious Disease Register (NIDR) in Finland. The aim of this study was to identify explanatory variables for VTEC infections reported to the NIDR in Finland between 1997 and 2006. We applied a hurdle model, applicable for a dataset with an excess of zeros.</p> <p>Methods</p> <p>We enrolled 131 domestically acquired primary cases of VTEC between 1997 and 2006 from routine surveillance data. The isolated strains were characterized by virulence type, serogroup, phage type and pulsed-field gel electrophoresis. By applying a two-part Bayesian hurdle model to infectious disease surveillance data, we were able to create a model in which the covariates were associated with the probability for occurrence of the cases in the logistic regression part and the magnitude of covariate changes in the Poisson regression part if cases do occur. The model also included spatial correlations between neighbouring municipalities.</p> <p>Results</p> <p>The average annual incidence rate was 4.8 cases per million inhabitants based on the cases as reported to the NIDR. Of the 131 cases, 74 VTEC O157 and 58 non-O157 strains were isolated (one person had dual infections). The number of bulls per human population and the proportion of the population with a higher education were associated with an increased occurrence and incidence of human VTEC infections in 70 (17%) of 416 of Finnish municipalities. In addition, the proportion of fresh water per area, the proportion of cultivated land per area and the proportion of low income households with children were associated with increased incidence of VTEC infections.</p> <p>Conclusions</p> <p>With hurdle models we were able to distinguish between risk factors for the occurrence of the disease and the incidence of the disease for data characterised by an excess of zeros. The density of bulls and the proportion of the population with higher education were significant both for occurrence and incidence, while the proportion of fresh water, cultivated land, and the proportion of low income households with children were significant for the incidence of the disease.</p

Using the World Wide Web to develop key professional skills in veterinary undergraduates

This paper outlines the pedagogical and practical reasons for developing two interactive online pathology modules for use by third-year undergraduates in veterinary medicine at the University of Glasgow: namely, to further students' understanding of general and systems pathology, as well as their acquisition of key professional skills, and to provide access to a core-elective system of education and to subsequent employment and lifelong learning

A descriptive study of 'kangaroo gait' in sheep in northern Britain

Two questionnaires were undertaken to obtain improved knowledge of the signalment, incidence and risk factors of the condition termed 'kangaroo gait' (KG; a forelimb locomotor disorder of adult female sheep). The first survey was mailed to 221 veterinary surgeons in practices in northern Britain which provided veterinary care for sheep, and the second was mailed to 438 sheep-flock owners and managers located in the Scottish Borders, who were recruited via their veterinary surgeons. Responses of 84.7 and 30.7% were achieved, respectively. In total, 29.7% of veterinary practices and 24.1% of flock owners and managers had identified one or more cases of KG in their practice area or flocks since the first case was reported in 1976. Almost all respondents indicated that adult females were affected-usually during lactation (and less commonly during late gestation). KG was more common among commercial crossbreeds and less common among sheep grazing hill pasture (than sheep grazing upland or lowland pasture). Cases usually occurred between March and June while sheep were at grass, although it was unclear whether the temporal pattern was associated with grazing or lambing patterns. Stocking densities were significantly higher among affected flocks than among non-affected flocks. The annual number of individuals and flocks identified as being affected had increased since the condition first was identified. Most cases of locomotor disorders resembling KG were not reported to veterinary surgeons. (C) 2003 Elsevier B.V. All rights reserved