Bad weeds

Ruby has been out on pasture for the last week (off and on for a couple months) and has been loving it.  I love seeing her on pasture rather than in a big pen, and her calf has the best time running around.  The only thing is - whatever weed is out in that pasture that she's eating, it's making her milk taste horrible!  It goes straight to the dogs.  I don't know if it is only a weed that is just now up and growing strong or what, but she has to live back in the pen.  If she were a beef cow this obviously wouldn't be an issue, but since her milk is a family staple we will bring her in.  Like the "don't-eat-that" sheriff of pasture land, I'm bringing her in lol.  I can only hope that once the grasses/weeds mature she can go back out without spoiling the milk.   She stayed in for the first time this morning, and mooed at me when she realized I was leaving her there.  Talk about feeling like a heel!