Thanks for the video reference. I had already watched one where they inserted several hens into the rooster's cage one after another. Interesting. Reminds me of the Taiwanese method of producing "mule ducks".
I will attach part of an article from Feathersite. It is quite detailed on the care and feeding of Green Junglefowl. This particular piece caught my eye: "The subadult junglefowl have special problems associated with their dietary requirements and growth stages. Too much crude protein will curl the toes and legs." I lived in Laos for many years and a friend of mine is a fighting cock fancier. These roosters are the Indian Game or Thai Game type. He told me that the young birds would have leg problems if you fed them on commercial chick starter and grower. He fed them a diet rich in broken rice. Not a lot of protein. I secretly scoffed at this (a foreigner always knows better) until I acquired a couple of young game chicks. We fed them the same as the bantams and others and sure enough, when they were getting pretty big, one of them got very weak in the legs and spent a lot of time sitting down. He could walk, but very unsteadily. We fed him a less rich diet - more paddy rice and broken rice, and he got over the leg weakness after a few months. He was the larger of the young roosters when the leg weakness occurred. He was also the purer-looking gamecock.
I have worked in the US for a large Broiler Breeder and all the breeders had problems with their male lines . The male lines had leg problems. What was the main genetic input into their male lines...? The Thai or Indian Game. The solution was to breed for better legs and to restrict their diet during the growing period. I don't know what the diet composition was as I only managed the farm and the feed was sent to us. I imagine the formulas could be located from feed companies.
I will look for a good photo of the Thai Game cocks. The good ones have a single throat lappet like a Green Junglefowl, tight feathering like the GJF, long legs, pea combs, etc.. It is a strong type. Crossing to a regular local hen will still result in young that look strongly gamecock. Strong linkage among their genes, which appear to be generally dominant. I have always felt that these gamecocks must have a different origin than the RJF-descended birds. Just too different and a strong heredity unit.
I think there is a very good chance that these Thai Game chickens are carrying a lot of Green Junglefowl genes. I would use these hens with a Green Junglefowl cock to see if there would be more chance of fertility in the F1 hens and in the general hybrid stock.
I think it might provide an advantage if you used these hens with a GJF cock.
Worth a try.
I can't figure out how to attach photos or documents, but if you go to: Google - 'Thai Game Chickens photos' - you will find lots of pictures - most of which are copyrighted.
