It is very important to evaluate the effectiveness of those methods, like vaccine or probiotics and this should be done first under an experimental challenge study, which needs to challenge the pigs with the bacteria and then see how they respond to infection in pigs vaccinated as opposed to those not vaccinated as opposed to those not received it and it's very important to have an infection model.
When I'm talking about the infection model that means that there are different parameters that will have impact on pig response to the infection.One of them is, for example, the age of the pig.
The genetics of the pig is another parameter, how much bacteria we should give to the pigs to induce diseases in them. These are main parameters that we need to optimise an infection model first and then use that infection model to evaluate intervention.
Dr. Farzan says it's important that the infection model deliver enough of the infectious agent to trigger a disease response but not enough to kill the pig.
Source : Farmscape.ca