Young Blonde Girl In The Hay With The Orange Scarf

Large bales
Many farmers, particularly those who feed large herds, have moved to balers which produce much larger bales, maximizing the amount hay which is protected from the elements. Large bales come in two types, round and square. "Large Square" bales, which can weigh up to 1000 kg (2,200 lb), can be stacked and are easier to transport on trucks. Round bales, which are typically weigh 300–400 kg (700–900 lb), are more moisture-resistant, and pack the hay more densely (especially at the center). Round bales are quickly fed with the use mechanized equipment.
The ratio 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 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.
For animals that eat silage, a bale wrapper may be used to seal a round bale completely and trigger the fermentation process. It is a technique used as a money-saving process by producers who do not have access to a silo, and for producing silage that is transported to other locations. However, a silo is still a preferred method for making silage. In very damp climates, it is a legitimate alternative to drying hay completely and when processed properly, the natural fermentation process prevents mold and rot. Round bale silage is also sometimes called "haylage," and is seen more commonly in Europe than in either the USA or Australia. However, hay stored in this fashion must remain completely sealed in plastic, as any holes or tears can stop the preservation properties fermentation and lead to spoilage.