A study of the impact of population bottlenecks on the genetics and morphology of reindeer (Rangifer tarandus tarandus) on the island of South Georgia

Numerous studies have shown that population bottlenecks result in loss of genetic diversity and as a consequence of this, it is commonly inferred that there is a loss of evolutionary potential. It is rare that circumstances are such that there should be well documented details of the founder event, such as the size and date of the bottleneck, that there should be access to subsequent demographic information and to suitable samples from both the post-bottleneck and the source populations. It is even less common for this information to be available for two separate bottlenecks that occurred in parallel in a largely unmanaged population of large mammals. The importation by whalers of two separate groups of reindeer (Rangifer tarandus tarandus) onto the island of South Georgia in the early part of the twentieth century provided precisely those circumstances. There are accurate historical records of each founder events with details of dates and numbers of reindeer. The inaccessibility and geography of the island ensures that the South Georgia reindeer herds have been isolated from immigrants and separated from each other. The aim of this study was to test hypotheses about the impact of population bottlenecks on phenotype and genetic diversity and this was achieved by making genetic and morphometric comparisons of both post- bottleneck populations with the source population in Norway. Genetic diversity was primarily measured by allele numbers and heterozygosity based on data from thirteen microsatellite loci. Morphometric comparisons included measures of developmental stability, notably fluctuating asymmetry (FA), as well as phenotypic variation and body size. Each of the post-bottleneck populations showed significant genetic differentiation from the pre-bottleneck population and showed decreased levels of heterozygosity and allelic diversity. The data was used to validate commonly used 'bottleneck signatures' and considerable variability was found in the accurate detection of the known bottlenecks by the different detection methods. Both the post-bottleneck populations showed increased FA and morphometric variation compared to the pre-bottleneck population in some of the measured traits. Both post-bottleneck populations had smaller overall skull size than the pre-bottleneck population though it is discussed that this may be due as much to a plastic environmental response as to a consequence of the genetic bottleneck. Within each population the relationship between measures of genomic diversity and indirect measures of fitness were investigated on an individual basis. Although the results were of low significance, weak associations were found to support the hypotheses that developmental stability is correlated with measures of genomic diversity even at the level of the individual

Can farmers reliably perform neonatal lamb post mortems and what are the perceived obstacles to influencing lamb mortality?

Neonatal lamb mortality constitutes a significant economic cost and is an important welfare challenge. Despite compelling evidence for reduction strategies and cost benefits associated with them, there has been no documented reduction in mortality since the 1970’s. We aimed to evaluate whether a knowledge exchange solution could be used to define farm specific loss risks accurately. This was done by training farmers how to examine neonatal lambs post-mortem to record and interpret common causes of mortality by following a basic framework. We used participatory rural appraisal to assess some of the existing challenges to reducing lamb mortality. When considering outcomes for specific post mortem questions, there was 87.5% agreement between veterinary and farmer answers and 82.3% of farmer diagnoses (n = 96) agreed with the veterinary conclusions. When merged with farmer performed post-mortems, farm specific mortality pie-charts were developed to highlight the variation between flocks and the necessity for flock specific advice. Common challenges to reducing lamb loss included level of labour, skill set of labour, communication within teams and whether farmers generally considered post-mortems to be a valuable tool. We consider that farmer post-mortems of lambs could be a tool for the veterinary-farmer team, facilitating the communication of farm specific advice and empowering farmers to effect positive change

Dealing with maedi visna in UK sheep flocks

Background: Maedi visna (MV) is considered to be one of the ‘iceberg diseases’ of sheep; a group of infectious, production-limiting diseases which are endemic to the UK. Characterised by slow, progressive onset, these diseases lie undetected and can have a large impact on flock efficiency. This group of diseases also includes border disease, caseous lymphadenitis, ovine Johne’s disease and ovine pulmonary adenocarcinoma. The prevalence and effects of these diseases within different UK flock types remains unknown. Aim of the article: To highlight the increasing importance of MV within the national flock. Here, we discuss the production effects, diagnosis and control options for MV

Update on caseous lymphadenitis in sheep

Background: Caseous lymphadenitis (CLA), caused by the gram-positive bacteria Corynebacterium pseudotuberculosis, has been present in Great Britain since the 1980s and is now considered endemic. CLA is considered to be an iceberg disease; that is, it is a production-limiting disease, characterised by slow insidious onset, that has production-limiting effects in a larger proportion of the flock than is exhibiting clinical signs at any given point in time. Aim of the article: The disease has been previously reviewed in In Practice (Baird 2003). In this article we consider updates in our understanding of the pathology, risk factors for flocks and the challenges of initiating control where the cost of the disease is still relatively unquantified

Variable selection for inferential models with relatively high-dimensional data: Between method heterogeneity and covariate stability as adjuncts to robust selection

Variable selection in inferential modelling is problematic when the number of variables is large relative to the number of data points, especially when multicollinearity is present. A variety of techniques have been described to identify ‘important’ subsets of variables from within a large parameter space but these may produce different results which creates difficulties with inference and reproducibility. Our aim was evaluate the extent to which variable selection would change depending on statistical approach and whether triangulation across methods could enhance data interpretation. A real dataset containing 408 subjects, 337 explanatory variables and a normally distributed outcome was used. We show that with model hyperparameters optimised to minimise cross validation error, ten methods of automated variable selection produced markedly different results; different variables were selected and model sparsity varied greatly. Comparison between multiple methods provided valuable additional insights. Two variables that were consistently selected and stable across all methods accounted for the majority of the explainable variability; these were the most plausible important candidate variables. Further variables of importance were identified from evaluating selection stability across all methods. In conclusion, triangulation of results across methods, including use of covariate stability, can greatly enhance data interpretation and confidence in variable selection

Antimicrobial use practices and opinions of beef farmers in England and Wales

© British Veterinary Association. Background Limited research exists on antimicrobial use practices of beef farmers. This study aimed to investigate antimicrobial practices and perceptions of beef farmers in England and Wales, and identify drivers of higher antimicrobial use for treatment of bovine pneumonia. Methods A survey was sent out in 2017 to beef farmers in England and Wales who supply to two abattoirs. Descriptive statistics were used to summarise the data. A logistic regression model was built to determine factors associated with treating greater than 5 per cent of the predominant group in the herd with antimicrobials for pneumonia. Results There were a total of 171 useable responses. Most farmers reported using antimicrobials in less than 5 per cent of their herd for the treatment of common diseases. Most farmers (90 per cent) reported that they understood what antimicrobial resistance means, but only 55 per cent were aware of critically important antimicrobials and 9 per cent could name at least one critically important antimicrobial. Having a calf-rearing enterprise and not considering Johne's disease when buying in cattle were associated with using antimicrobials to treat pneumonia in greater than 5 per cent of the predominant group in the herd. Conclusion Self-reported antimicrobial use appears to be low in beef farms. However, some gaps in understanding aspects of antimicrobial stewardship by farmers were identified

Responsible use of antibiotics on sheep farms: application at farm level

There is currently global concern over rising levels of antibiotic resistance among commensal and pathogenic bacteria in human and animal populations. Unless urgent action is taken by the medical and veterinary professions, it is thought that we will enter a postantibiotic era in which bacterial diseases that were readily treatable with antibiotics will kill once again. Consequently, antibiotic use in both the human and animal health industries has come under intense scrutiny. Long-held ideas and accepted behavioural norms have rightly been challenged. Progress in the agricultural industries has developed apace with the establishment of the Responsible Use of Medicines in Agriculture Alliance Targets Task Force in December 2016 and Defra’s call for the implementation of sector-specific targets on the use of antibiotics. This article describes how veterinary surgeons and sheep farmers can work together to plan, prevent and protect against three specific disease management issues – infectious lameness, enzootic abortion of ewes and neonatal bacterial infections – by replacing, refining and reducing the use of antibiotics on farm, based on guidelines drawn up by the Sheep Veterinary Society

Understanding farmers' naturalistic decision making around prophylactic antibiotic use in lambs using a grounded theory and natural language processing approach

The routine use of antibiotics for prevention of disease in neonatal lambs has been highlighted as inappropriate, yet research suggests that many farmers in the UK still carry out this practice.The aim of the study was to understand farmers' naturalistic decision-making around prophylactic antibiotic use in lambs. Data from 431 posts by 133 different users of an online discussion forum were analysed quantitatively using natural language processing and qualitatively using a grounded theory approach. Results from the qualitative analysis identified five categories that influenced farmers risk perceptions around prophylactic antibiotic use in lambs: anticipated regret, negative emotions and experiential avoidance; economic considerations; farmer identity; perception of capability; and perception of social judgement. Natural language processing analysis of the posts by the study group were compared to posts on topics unrelated to antibiotic use by control groups from the same forum to understand the underlying style and tone within the text. Analytical thinking and authenticity scores were significantly lower in the study group compared to the control groups (P [less than] 0.01). Words relating to cognitive processes were significantly higher in the study group compared to the control groups (P [less than 0.01). Results of the qualitative and quantitative analysis were integrated to assess the fit of the data and enhance findings from either method alone.The key findings were the identification of reasons why farmers used antibiotics prophylactically in neonatal lambs. Farmers disassociated the use of oral antibiotics in neonatal lambs from other types of antibiotics within sheep farming. Farmers used the concept of luck and uniqueness to justify their prophylactic antibiotic use. This may explain farmers' low analytical thinking scores as this reflects a more personal style of thinking as farmers express their thoughts on antibiotic use on an individual basis. Farmers' felt that they did not have the capabilities to control neonatal disease without antibiotics during busy periods and this was exacerbated by external economic constraints. For farmers' who used antibiotics for therapeutic use, fear of social judgement was an important factor in their perceptions of risk around antibiotic use. The high frequency of negations and conjunctions suggested feelings of moral duty. As such, antibiotic use has developed into a symbol of their good farming identity which conflicted with the identity held by those who used antibiotics prophylactically. These results can be used to inform knowledge exchange around prophylactic antibiotic use in lambs to improve antibiotic stewardship in the sheep farming sector

To prescribe or not to prescribe? A factorial survey to explore veterinarians’ decision making when prescribing antimicrobials to sheep and beef farmers in the UK

Resistance to antimicrobials is one of the biggest challenges worldwide for public health. A key strategy for tackling this is ensuring judicious use of antimicrobials in human and veterinary medicine. Whilst there are many studies in human medicine investigating prescribing behaviour of doctors, there is limited work to understand what factors influence veterinarian prescribing behaviour. Veterinarians often prescribe antimicrobials to sheep and beef farmers in contexts other than at a clinical consultation, and decision-making behind this has not been explored. The aim of this study was to measure, for the first time, the influence of factors from social theories on veterinarians’ decision to prescribe antimicrobials to sheep and beef farmers without a clinical consultation, using a factorial survey approach. Respondents were presented with eight vignette scenarios, where a farmer asks for antimicrobials at the veterinary practice. Seven factors, identified from constructs of social theories, were included in the vignettes. Random intercept and random slope models were built to estimate the effects of the vignette factors and vet characteristics on the respondents’ willingness to prescribe ratings. A total of 306 surveys were completed. The vignette factors: case type, farmer relationship, other veterinarians in practice, time pressure, habit, willingness to pay, and confidence in the farmer, were significant in the decision to prescribe. Confidence in the farmer was the most influential vignette variable, and was included as a random slope effect. Respondent variables with significant influence on the decision to prescribe were agreeableness personality score, region of veterinary practice, and presence of a small animal department. These influential factors could be considered to target interventions in beef and sheep farm animal veterinary practice for improved antimicrobial stewardship

Increasing vet and sheep flock interactions in dairy practice

© 2019 BMJ Publishing Group Limited. Sheep medicine has traditionally been a low priority for cattle-dominated practice, as it is commonly thought that there is minimal financial opportunities in this sector. The perception has been that the vet's role regarding sheep is that of an emergency care provider and that farmers would be reluctant to pay for training and preventive advice. As such, this has inhibited investment in sheep services within farm animal practices that predominantly focus on dairy cattle, as these services are deemed less lucrative revenue streams for the business (Bellet and others 2015). In this article, we explore the challenges associated with delivering sheep preventive medicine within private veterinary practice, and look at how, by harnessing positive relationships with commercial flock owners, farm animal practices can develop this service