Are you able to see how they keep the birds, particularly in terms of nutrition and housing? Based upon what I can see on the internet, they are kept under much more tightly managed conditions even during the juvenile stage. Opinions on their keep in the US are not consistent. They mature slow, like my strain of American Games. They are also smart in some ways, and not smart in other ways. They take cold better than I thought, but are not as frugal with feed when temperatures drop. They are slow, but have good endurance. Selection on them has been intense to promote the odd posture and feathering which has multiple loci involved as grades into American Games are obvious even after four generations.
(Sorry for the late reply)
I believe the type of housing you are talking about are khuda as shown in this Youtube video:
There are many breeds of Aseels in Pakistan and many types of blood line within those breeds each blood line is different, for example with in mianwali Aseel breed you will find many blood lines some blood lines will be tall height and some blood lines will be small hight, and some blood lines will be fast and will have low endurance While some blood lines will be slow but have high endurance and some blood lines will be fast and have high endurance(mine have never fought and will never fight so I am not sure about them but I can tell you my bigger Aseel roosters are slower but a lot more braver than my smaller Aseel roosters).
The feed given to Aseels in Pakistan in summer is Pearl millet(Bajra) which is soaked in water for some time and then washed and given to birds, some times but not often in summer little quantities of other types of grains and poultry feed are mixed with Pearl millet to complete the birds/Aseels nutritional requirements, they are also given diffident Types of vegetables and fruit.
Aseels in the winter are given a mixture of different grains and poultry feed/pellets ( some of the grains are pearl millet, corn, red rice, small white rice, chickpeas, lentils, wheat, oats)(they are also given 13 and 14 number chicken feed not hundred percent sure).
(I am just a hobbyist and not an expert so take my information with a grain of salt)
(sorry for grammatical and spelling mistakes)