Yes, we did keep a calf in our front yard this summer.  And yes, I did let her out to graze in the neighborhood.  Which worked out better than you might guess.  She had no interest in the road, as nothing green grows there.  If she wandered too far or got scared, she came running back home.  Yes, it was a bit cavalier, letting her go like that.  But she did well, taught me plenty about cow-nature, and it was a temporary and enriching event for everyone on the road.  Who doesn't want to live where the cows come home?  "The kai come heem" as it were.