To my understanding there is still a border control for milk protein coming into the country.
After the TPP is signed, over a number of years that border control on protein supplements will disappear. That is an open door for processors in Canada to use components elsewhere in the world and get higher yields from Canadian milk. That will mean they either have to grow the market to that level of higher yielding cultured products, or they will have to reduce the amount of milk received from Canadian farms.
I think that is the dangerous part of the TPP. In a few years we will have the door wide open for milk components to be imported without any tariffs. That's the danger there.