Long before the days of large dairy herds, people were making very large wheels of cheese, weighing 40, 50, 80, 100, and up to 220 pounds. Larger wheels not only simplified the cheese-making process (it's easier to make one large wheel than several small wheels), but also served as a way to efficiently preserve large quantities of milk in the form of cheese that could be stored for several years.
The milk for these large cheeses has to be available within a short period of time, usually 24 hours before cheese making begins. Clearly, a lot of animals are needed to produce milk for these wheels, so early dairy farmers began pooling the milk from different herds to make these cheeses.
But other, smaller cheeses have also benefited from regionally pooled milk. Morbier, a French cheese from the lower Jura region, is made in two parts. One part is morning milk, from which raw-milk curds are formed into hoops and covered with a layer of vegetable ash. The second part is evening milk, from which raw-milk curds are put on top of the vegetable ash, the entire wheel is salted and drained, and then it is aged in caves where it develops a natural, briny rind, lending it a hint of delightful piquancy. With multiple herds to draw from, many wheels of Morbier can be made at the same time.
Pooled-milk cheeses are quite famous. They are made in huge sizes, so that all of us may enjoy them. Gruyere normally weighs about 85 pounds, Emmental weighs close to 220 pounds, and Parmigiano-Reggiano weighs between 70 and 80 pounds.