I would pass on feeding it to my cows... Due to the love of my horses - I do not chance having moldy hay around! However, many (and I do mean MANY) around here would put it to use. I would put it on Craigslist with mention of the mold and let the cow people decide for themselves. What seems like horrid hay to horse people, might be fine for cow hay. Many vets in this area say "They're cows, it won't matter". On another note, I would avoid burning them. Round bales of hay (and square bales stacked) can burn/smolder and even relight for weeks (even after the fire dept has soaked the place)! I am thinking we use to use lime on them and they would erode away fairly quickly. Good luck with which ever route you choose.
I burn our moldy hay and turn it into the compost (the ashes make super-compost). If that isnt an option, you can plant thinga like gourds and pumpkins directly into the bales and they grow 99% of the time. Use it for landscaping? Till it into your garden?