This isn't an easy task. We're advised to take civil action against the trespassers. First, the producer must be willing to take the case to court. They'll need to deal with all kinds of emotions. They'll need to find evidence to determine who among the 15 protesters brought in the disease. Will the entire group pay for the damage?
The family in question lost tens of thousands of dollars in a few weeks because deaths occurred as soon as the trespassers entered the farm. At the time of the break-in, the animals were expecting to be fed, but they weren't fed. The mothers got up, lay down again, got up again, and then crushed their young. Who will pay for this? The next step is to show evidence in court. These farmers currently have no defence options backed by legislation. They must defend themselves, and that's very difficult.