Avoid substituting corn as more than 50 percent of the ration. Higher protein feeds, such as soybean hulls, corn gluten feed or commercial mixtures, often improve forage utilization and consumption. Corn usually doesn't add enough protein to low-quality hay, so you need a supplemental source of protein. Other grains , such as milo, oats, barley or wheat, will require some processing. By-product feeds may include soybean hulls, whole cottonseed, corn gluten feeds, wheat midds or others.
Broiler litter is another possibility if it's available.
Just remember a few things about by-product feeds. By-product feeds are often high in moisture. This makes transporting them expensive and may make them unstable for storage. Always calculate the value of feeds on a dry-matter basis. Carefully evaluate the nutrient composition of the by-product feed.