Application of multiblock modelling to identify key drivers for antimicrobial use in pig production in four European countries.

Antimicrobial use in pig farming is influenced by a range of risk factors, including herd characteristics, biosecurity level, farm performance, occurrence of clinical signs and vaccination scheme, as well as farmers' attitudes and habits towards antimicrobial use. So far, the effect of these risk factors has been explored separately. Using an innovative method called multiblock partial least-squares regression, this study aimed to investigate, in a sample of 207 farrow-to-finish farms from Belgium, France, Germany and Sweden, the relative importance of the six above mentioned categories or 'blocks' of risk factors for antimicrobial use in pig production. Four country separate models were developed; they showed that all six blocks provided useful contribution to explaining antimicrobial use in at least one country. The occurrence of clinical signs, especially of respiratory and nervous diseases in fatteners, was one of the largest contributing blocks in all four countries, whereas the effect of the other blocks differed between countries. In terms of risk management, it suggests that a holistic and country-specific mitigation strategy is likely to be more effective. However, further research is needed to validate our findings in larger and more representative samples, as well as in other countries.