Greenpeace action against genetically engineered animal feed with a transparent cow at maize field. Activists are holding signs that read "Campina don't feed cows with GMO's". Dairy companies Campina and Muller are known for using dairy from farmers who feed their cows with genetically engineered fodder. Greenpeace demands that these two of Europe's largest dairy companies stop buying their milk from farmers who grow genetically engineered maize to avoid potential contamination of the food chain.