The issues that we are trying to deal with are relatively new, within the last five years, so I have a hard time believing that it is actually a mineral deficiency. It seems more likely to me that it is a disease problem than a mineral deficiency. We went for enough years without any mineral at all and didn't have any of the problems we are seeing now. I know that it isn't a cumulative thing where it just took some time for the deficiencies to show up because there have been several generations of cows come and go that received at best, infrequent supplementation.
As to whether or not the vet sells it, I don't know, what difference does that make? Should I be suspicious of someone telling me I need a mineral supplement if they also sell mineral?