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

Abstract

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.

Keywords: Salmonella; biosecurity; cattle; dairy herds; prevention; tools.

Figure 1

Overview of the elements of the new biosecurity assessment framework for S. Dublin introduction and establishment on dairy cattle farms (BAF-SD).

Figure 2

Flowchart of the 7-step process for performing on-farm observation and interview-based biosecurity scoring and data collection using the S. Dublin-targeted biosecurity assessment framework (BAF-SD) for dairy cattle farms.

Figure 3

Illustration of a farm overview. Logistics include routes of movement of livestock manure, internal routes of feed handling, and possible cattle movement tracks. Fourteen predetermined locations are marked on the map, including locations for farm entrance, pickup-delivery of youngstock, cows or animals for slaughter, calving facilities, sick pen, calf housing facilities, slurry tanks, storage of solid manure, a collection point for biogas, delivery of digested residues (biomass), storage of protein supplements and concentrates, storage of forage, washing facilities, and rendering collection points.