Semi-Quantitative Biosecurity Assessment Framework Targeting Prevention of the Introduction and Establishment of Salmonella Dublin in Dairy Cattle Herds

Simple Summary: The importance of implementing protective measures is related to herd size because of potentially more external contact and the ability of each animal to get in contact with more animals. Therefore, with an increasing number of animals in cattle herds, biosecurity is becoming increasingly essential. In particular, cattle-adapted diseases, such as Salmonella Dublin, can survive in the environment for an extended period after it has been excreted in the faeces of infectious animals. Therefore, indirect spread mechanisms, such as the movement of bacteria by contaminated equipment from farm to farm with the risk of contaminating the cow environment and food before oral intake by other animals, become more important. Additionally, the ability to survive in the environment can enhance the risk of the bacteria becoming established as an infection within the herd if improper management procedures compromise hygiene. In this study, we designed an approach and a tool based on existing knowledge, which could be used in further research studies to evaluate the risk of some dairy herds becoming infected compared with others. 'The assessment can be performed through observation of farms (similar to 1 h) and interviews with the farmers (similar to 1 h). This can help reduce the spread of harmful bacteria in dairy cattle production. An increasing average herd size and complexity in farm structures call for a higher level of biosecurity. It can reduce the risk of introducing and establishing pathogens with multiple-pathway and indirect spread mechanisms, such as Salmonella Dublin, a pathogen with an increasing occurrence in dairy cattle farms across different countries and continents. Therefore, this study aimed to use existing knowledge to develop a framework with a supporting tool allowing for a time-efficient, yet comprehensive, assessment of biosecurity measures that can help prevent the introduction and establishment of S. Dublin in dairy herds. Based on the literature review, a seven-step biosecurity assessment framework was developed and evaluated in collaboration with biosecurity experts. The resulting framework includes a weighted semi-quantitative assessment method with a scoring guide in an electronic supporting tool for 12 biosecurity sections assessed through on-farm observations and farmer interviews. The framework and tool provide a novel approach to comprehensively assess the overall (mainly external) on-farm biosecurity level by a trained biosecurity assessor. They can be used for systematic data collection in epidemiological studies on risk factors for the introduction and establishment of S. Dublin in dairy farms. Preliminary interrater reliability testing indicated moderate reliability between assessors with varying biosecurity skills.