Many farmers, particularly those who feed large herds, have moved to balers which produce much larger bales, maximizing the amount of hay which is protected from the elements. Large bales come in two types, round and square. "Large Square" bales, which can weigh up to 1,000 kilograms (2,200 lb), can be stacked and are easier to transport on trucks. Round bales, which typically weigh 300 to 400 kilograms (660–880 lb), are more moisture-resistant, and pack the hay more densely (especially at the center). Round bales are quickly fed with the use of mechanized equipment.
The ratio of volume to surface area makes it possible for many dry-area farmers to leave large bales outside until they are consumed. Wet-area farmers and those in climates with heavy snowfall either stack round bales under a shed or tarp, but have also developed a light but durable plastic wrap that partially encloses bales left outside. The wrap repels moisture, but leaves the ends of the bale exposed so that the hay itself can "breathe" and does not begin to ferment. However, when possible to store round bales under a shed, they last longer and less hay is lost to rot and moisture.