Rust on oats

About 7-10 days ago just as my spring oats were starting to head out I started seeing some rust on the lower leaves. In a weeks time the rust spread very quick and a large majority of the leaves were covered and some of the lower leaves have already turned brown and died. Today was the first chance I had to cut the oats for hay and there was a orange cloud of the rust coming off them as they were being cut and the haybine is orange. What I'm wondering is how the leaves with the rust will affect the feed quality of the hay?

I have never dealt with rust to this extreme before.....certain parts of the field was worse than others but pretty much the whole field was affected. It was amazing how fast it spread on the plants.

Rust on oats