Check out my FAQ suggestions on the organic garden forum:

Cattle Feed Suggestions

My uses of Cattle Feeds:
1. Compost Nitrogen Activator to make the compost pile hotter.
2. Soil amendment. Great for use under mulches for extra NPK.

3. Compost tea ingredient. Great nitrogen source for teas. Similar to alfalfa teas.

4. Great cheap cover crop seed source and fertilizer. I plan to sprinkle a lot of cattle feed on top of compost in my fall/winter cover crop beds to make the extra wheat and oat seeds
sprout with my other green manure seeds.

5. Attracts lots of beneficial soil organisms and birds. The birds fight pestsy bugs. The microbes help digest the organic matter in the soil, thus producing more available soluble nutrients for plants.

6. The molasses in sweet feeds is beneficial to breed beneficial microbes in the soil and in compost teas. Soil and compost microbes love carbon for energy (simple sugars contain lots of carbon).

7. The corn meal in cattle feeds is a great natural fungicide.

If you want some real bargans find a farmer to buy direct from at harvest. Oats, wheat, and corn are usually under $3.00 per bushel. Soybeans are around $5.00 per bushel. Ryegrass hay, the sudex hybrids, and oat hay are priced somewhere around $25.00 for a 1000 to 1500 pound roll. Often last years old half rotten hay can be gotten for just hauling it away. When corn is chopped for silage you could get a truck load from picking up the spillage. In fact there is often a lot of spillage of all types of crops at any transfer point from combine to truck.

You don't know any farmers? Ask your local county agent for likely prospects.