And what do you think is the name of each breed in Spanish in South America?
We have local criollo birds that we have been raising for the past two years. What this Ugandan fellow mentions are all things we have observed.
https://www.youtube.com/watch?v=UlLLtYozLOk
They really do take at least 6-8months before you can consider harvesting them. I wish someone would have told us that before we started. Since we kind of do a Salatin style tractor and let them loose free range during the day, they have good sanitation and always access to fresh grass and bugs. They have not had hardly any disease problems, however I think it's due to the way we raise them and not necessarily their genetics.
We want a good in-between bird. One extreme is the cornish cross factory-farmed bird that takes 1.5-2 months, but is extremely fragile, requires nearly perfect conditions and a really well-balanced feed. The other extreme are these criollo chickens that take 8 months to get big enough.
The cornish cross wouldn't work probably for these reasons: The ground is soggy in many places and they will have to sleep on the ground (not a problem for the criollos). We currently move tractors every other day and the birds only use the tractors for sleep or shelter from storms. We want the birds out in the silvopasture orchard (the landscape is an orchard) so they can catch bugs and supplement their nutrition with fallen/rotten fruit. Cornish cross seems too cumbersome to effectively catch bugs. Plus the topography is steep and irregular, so I'm not sure their legs would tolerate it.
Wants: Birds that are ready from hatch to harvest in 3-4 months (or faster). Able-bodied to deal with the topography and scavenge a large portion of their diet. Able to succeed on just whole-kernel corn and cooked beans as feed. The orchard is young, and fruit probably won't be a reliable source of food for at least another two years.