The hay thing fake-triggered me. Manure is a combination of shit and things like wheat or barley straw, usually. So yeah, if the straw came from a plant that was GMO and sprayed with chemicals, you'd find those traces in the straw. It doesn't necessarily mean the cow actually ate it and shit it out. We wouldn't normally feed a cow something like wheat because that would be far too expensive and a waste of good wheat. Even some of the corn fed cows now are simply sent directly into a corn field to chow down on whatever they want from the entire plant still growing in the ground, and because the farmer wants to feed the cows for a low cost, that corn crop wouldn't be sprayed. It would actually be the shittiest feed corn you've ever seen. Of course, things are different all over the world. I'm in central Canada. There's such an abundance of natural grassy areas and they don't go to waste. It's those big city slickers and their lawn clippings that go straight into the garbage wasting the good cow food, even though everyone dumps chemicals on their lawns now. It's ridiculous.