It's posted to whomever all generally.

Far as I know, grazing fields are not usually fertilized at all. If anything, they are sown with oats, clover, chick peas, whatever types of high nitrogen replacing grasses, and the cattle drop their dung in an ongoing cycle. Fertilizers are used on farmland, not pasture. Manure from cattle kept in feed lots as opposed to open range grazing is another matter altogether, hard to say what they are fed. Far as genetically modified oats or grasses I really am not sure.

Monsanto is a big problem, I think a lot of farmers and ranchers are aware of it though. There is some concern not just about GMO species polluting the strains of natural species but actually having the ability to kill them off altogether, acting like a herbicide.