At the time the decision to eradicate was announced there were more than 400 properties on regulatory controls.
MPI said in a statement the number would fluctuate as it continued to trace animal movements and test properties with links to infected properties but farmers could take heart that this number had halved over the last few months.
"It shows that we are catching up to the disease and that the regulatory controls are working as intended to contain at-risk stock on infected properties."
All infected farms, and farms suspected of having Mycoplasma bovis have a Restricted Place Notice in place.
This prohibits all unauthorised movements of farm stock and other risk goods on to and off the property. This minimises the chance of the disease spreading from the property.
Any movement of cattle requires a permit from MPI.
Transport vehicles must follow a cleaning and disinfection process when they leave a restricted place.
A Notice of Direction aims to prevent further spread and doesn't restrict movement of stock or goods on to the farm.
Fifty-one properties have had their infected status removed.
MPI Mycoplasma bovis director Geoff Gwyn said recently the latest evidence was that things were looking positive for eradication.
"However, I know that a number of people are still doing the hard yards and this news may be of little consolation to them.
"We remain committed to ensuring our farmers and their families are at the centre of all our efforts as we continue to work towards eradication of M. bovis."
"Since the decision was announced to try for phased eradication, we have been working with a number of properties who are potentially at risk of being infected with M. bovis, the vast majority of which are tested and found to not have the disease. For those that do have the disease on their property, you are taking a big hit for the industry and I assure you, it does not go unnoticed or unappreciated."