You can't store leftovers and it takes quite a bit of effort to smoke or salt meat for preservation. Even with those methods of preservation there will still be spoilage.
You'd eat the oldest poultry that aren't laying any more, the oldest or most aggressive males that are causing problems within the flocks and birds injured in ways that they won't recover from. [later addition] Though, it wouldn't surprise me if most poultry wouldn't be truly domesticated as we think of it today, but you'd keep fields and marshes specifically to attract migrating birds like geese and ducks and wait to hunt them after they've hatched out the next generation and gotten fat to get ready for their next migration.
Milk from livestock only requires a single breeding of the milked animal every 18 months for cows. Probably a bit less for smaller animals. So only the oldest, injured, or problematic animals would be culled.
You can't store leftovers and it takes quite a bit of effort to smoke or salt meat for preservation. Even with those methods of preservation there will still be spoilage.
You'd eat the oldest poultry that aren't laying any more, the oldest or most aggressive males that are causing problems within the flocks and birds injured in ways that they won't recover from. [later addition] Though, it wouldn't surprise me if most poultry wouldn't be truly domesticated as we think of it today, but you'd keep fields and marshes specifically to attract migrating birds like geese and ducks and wait to hunt them after they've hatched out the next generation and gotten fat to get ready for their next migration.
Milk from livestock only requires a single breeding of the milked animal every 18 months for cows. Probably a bit less for smaller animals. So only the oldest, injured, or problematic animals would be culled.