Big bales of hay wrapped in plastic make baleage. Wrapping the bales of hay in plastic protects them from mold and rot. The hay has to be baled when moisture levels are just right and the plastic must completely seal the bale. There can be no holes. A hole the size of a quarter can cause a large area of rotting.
Baling high-moisture forage allows us to harvest earlier and avoid damaging storms when dry hay crops are typically down and it improves our yields in later cuttings. An advantage of baleage is getting hay harvested early before seed heads set, when nutrient content is highest.
Livestock benefit from improved feed quality, making more gains or milk.