Via Tyler Cowen, here's a totally totally surprising article from the Seattle Times.
I never in a thousand lifetimes would have expected anyone in the US to make money by exporting timothy hay, but they do, it seems. The hay on our farm was a mix: timothy, orchard grass, assorted vegetation. It was not great hay, to say the least. Apparently this outfit in Washington has great land and can make great timothy hay, hay which looks great, because that seems to be the major criterion for the Japanese who are the leading importers.
The secret is the hay is fed to racehorses (originally here in the US, now in several countries). So the hay is not important for its nutritional value, it's important for its looks, so the trainer can assure the owner that the horse is only eating the very best, the best because it's greenest. Given the uncertainty involved in racing, it's like the superstitions ballplayers have, something which gives emotional reassurance to all concerned.