Take one of the most prolific feed, genetically modify it to withstand your patented chemicals, then get the FDA to approve planting it.

GM Alfalfa has been approved by the FDA meaning that within a decade most alfalfa will be some strain of their alfalfa, meaning most animals will contain some of that alfalfa.

Since Monsanto has successfully sued farmers for allowing their corn to become contaminated with pollen from Monsanto's GMO corn in the next field, perhaps people can successfully sue Monsanto every time they find GMO contaminated alfalfa in their own feed?