What age is a sheep culled for its meat?

A sheep can be culled from the flock at any age. Generally culling means that the sheep is being removed from the breeding herd because of age, something wrong in the genetics, too closely related to other animals in the herd or illness, not necessarily strictly for being killed for meat. Culls can become someone else's pets!

Lamb that is grown specifically for meat are processed before one year of age.

Sheep older than one year are processed as mutton.