Description and typology of dairy sheep farm management profiles in Sardinia

Abstract

In the current decade, the major risk factors that play a role in bluetongue disease development have been studied, with many of these studies being carried out in order to help understand the spread of the disease. Although these studies have focused on environmental factors and territory features, establishing their role in bluetongue outbreak probability, little attention has been given to the analysis of the characteristics of farms at a micro-level. The main objective of this study was to identify farm management and groups with similar hygiene practice habits, i.e. “farm management”, providing a micro-scale characterization that has not been studied in detail earlier. A total of 5547 Biosecurity Habits questionnaire, based on examining the respect of all suggested practices against bluetongue, was completed by specialized veterinarians or agronomists, each involving a Sardinian sheep farm. Since the biosecurity items were dichotomous, multiple correspondence analysis was performed to summarize a set of categorical variables into a small number of orthogonal variables called principal components, and provide graphical displays. As the first two dimensions of multiple correspondence analysis accounted for more than 50% of the variability between farms, these were retained for the analysis. The first dimension generally defined the good/poor farm management, where good management was particularly associated with large farms. The second dimension was able to explain differences in hygiene conditions. Finally, the association of these gradients with bluetongue was assessed using logistic regression. There was a significant association (p < 0.0001) between the first dimension and the probability of bluetongue at the farm level, showing an important role in generally improving the management to prevent the disease spread. The high hygiene conditions (dimension 2) reveal a strong association (p < 0.0001) in preventing bluetongue, with approximately 1.5 times less probability of disease development as compared to farms with low hygiene and cleaning. This innovative micro-analysis could be an important support for future strategic programs against this vector-borne disease, which to date affects our region.