dont be an idiot, your point wasnt proven because that implies that milk production would accept non-maximum milk production.
first of all, the cow needs to have calved once to get the juices flowing, so to speak, so theres a must have pregnancy. it will then produce milk for about 300 days, though steadily declining in volume, more so if it isn't impregnanted again, then kinda be dry for 2 months, at which point, if everything went well, the cow calves once more to get the juices flowing once more. that happens like 2 - 4 times, at which point the cow is considered spent. and thusly retired and killed.
most of the male calves too. and a bunch of the female ones, depending on how many are needed to keep the endless cycle going.
not sure what you think the wild is, because for cows, its like, meadows. they function very well on their own on those. granted, they do appreciate like a wooden hut against wind and rain, but they can deal without those.
only thing that makes the breed for maximum milk production cows unsuited for wild life is the fact that they produce so much milk, they need to be milked constantly to keep their udders from literally bursting.