Sustainable dairy cows?

There was a point where we kept hearing how non-sustainable dairy cows were. 

Sure, they can be. . .like everything and anything. . . if mismanaged, misbred, misused.

This came from non-dairy animal folks, to be sure, but I still assume that misinformation might circulate out there among those that do not know better.

Our dairy cow is 100% Jersey: 25% full size / 75% Miniature. She is about 45'' tall. Not very small, at all. . .but a great homestead, traditional Jersey size. Smaller than what folks generally see now, yes.

She hasn't needed wormed since we've owned her. Needs nothing but air, sunshine and grass. . .by and large

. . .and she gives us 12 lbs of milk on once a day milking like clock work. . .no fuss, no muss. Check out that amazing body condition, too. . .FOR A DAIRY COW.

If that isn't sustainable, call me Fred 

I'd call her About the most useful creature on earth.