When beef are contract by lot, it is for a date, a certain number of animals, and a target weight. If a farm contracts 200 animals, it isn't those individually, it can be 200 random animals on that date.

Farms are penalized for animals outside the weight range, so contracts can be filled by sorting animals for the right weight. Because the animals aren't individually marketed, it can be hard to keep track of what contracts are filled and what contracts still need to be made.