Ideal large flightless birds for domesticated cattle

(Just a note about this question being a duplicate. Some of the points people raised on a basis to close the question were fair and some... weren't. I can close questions now, wheeeeeeeeeeeeeeee that sort of thing. I'm not sure why I haven't reposted it already but as four of the five people who voted to close it a while ago voted to reopen it of which I didn't cause I'm an idiot, I just voted to reopen now, which is where that one comes from I'd think it's reasonable to repost this)

So, just to be clear, when I mean "giant birds", I mean the families that presently consist of giant flightless birds (think moas, emus, ostriches, etc.) - the ones that came up with roughly similar body plans due to convergent evolution.

Given that we're using a large flightless bird (at least the ones which have existed), which one would be ideal to domesticate, using genetic engineering/selective breeding, with the goal of creating cattle? For now, we're just going to ignore whether this is a good idea or not, and beyond what motives a group or individual would have for doing such a thing.

To recap, ideal large flightless birds domesticated* for cattle purposes,

  • (Mild) Genetic engineering is a viable solution to make it feasible (if that wasn't clear before, eg modern knowledge and capabilities with regards to technology(genetic engineering technology and capabilities)
  • Presume any extinct birds are "resurrected" in identical to near-identical genetic forms, and then mild genetic engineering is applied from there. Any form of large flightless bird would be allowed regardless if they're currently extinct or not
  • Are raising them for meat and eggs
  • Doesn't matter if they're extinct or not(currently)
  • Were going to pretend I had remedied that some people had domesticated Ostriches AND Emus, and restate the question as any potentially large flightless birds which would be better suited for cattle roles
  • Edit:Would be preferably adapted for most climates, though a specific one is passable, as it can probably be artificially created and tended, and they're going to be fed, so not being able to forage doesn't really matter.
  • We are not on earth, so any environment in which a large flightless bird would be ideal with regards to raising them as cattle is available, and if there are multiple that fine, it's not a problem at all. It is Bird(s) now not Bird as it seems unlikely that there would be one sole bird ideal for cattle better at cattle-ing than every other large flightless bird.
  • Note: Genetic engineering isn't magic. It takes a large amount of time and energy to make minor changes to an organism. You can't use an animal as a template and make it from scratch, doing such a thing would probably take at least 20 years. Consuingly you can't really use it to make the "ideal" animal with goal X in mind, just make animal Y slightly better at doing X.
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    $\begingroup$ Edit the original question so that it is reopened. Reposting it won't allow you to go around the policies $\endgroup$ – L.Dutch May 13 at 6:16
  • $\begingroup$ Please also consider: It's hard to suggest one bird over another without knowing more about the world. Why birds? How established is your civilisation (colony ship, future-city, tribal groups, shipwreck)? How much water/predation/food is available? The moa or dodo come to mind for variety, or "just use chickens" for something we know is herdable. $\endgroup$ – Anon May 13 at 6:16