Hay cubes provide the next best fodder if baled hay is not available. Greedy eaters have been known to choke on cubes but soaking the cubes in water for 30 minutes to soften them can eliminate this danger. Be careful in hot weather that soaked cubes do not start to ferment.
Historically straw the (stems and leaves of grain plants such as oats, barely, or rye) was used as fodder, but this is no longer recommended. There is little nutritional value and straw can contain fungus dangerous to horses.
Wheat bran is a traditional supplement and rice bran is now available, but both can cause mineral imbalances if fed in large quantities.
Lawn clippings are dangerous. They can contain toxins from lawn chemicals, toxic weeds, and can ferment quickly in hot weather causing gastric distress, inflammation in the horse’s hooves, and even death.
Beet pulp is the left over pulp of sugar beets. It's mixed with molasses and formed into pellets that can be fed dry, or soaked in water to make a mash. Supplementing a horse's diet with beet pulp will reduce the amount of hay consumed, but it is not a replacement.