What are the requirements for fattening cattle?

Regardless of what you're feeding them, the general rule of thumb for fattening cattle is that you must have feed that is high quality (as in high in protein and energy), ad libitum access to loose salt-mineral and water, and good herd health management, especially for those cattle being finished on grain.

Grain-fed cattle can be fattened until they are around 18 to 20 months of age, but grass-fed cattle must be fattened until they are at least 24 months of age, but no more than 30 months.