so force feeding your rooster, hold him in you lap facing away and get something solid but easy to digest, scrambled or boiled egg sometimes soaked dog bickies are good, kind of wedge him under your left arm and have a blob of food ready in right, prize the beak open with the right hand and push food to back of beak(if you have to use two ppl, i to hold and prize the other to insert food., not down imto the breathing apperatus but as far back as you can. the baytril should start to kick in between 1 and 2 days. if you absolutley have to it is possible to crop feed a chicken, using a big maybe 20cc syringe giving him 5 ml at a time. and a crop feeding attachment(from most vets of pet supply stores) or a softish plastic pipe attached very securely to the end of same syringe, have a look for crop feeders on the internet, you should also find some good quality intsructions.. (crop feeding can be very usefull but the consequences of getting it wrong are immediate aspiration / death. but a chicken is a pretty big bird and if you feel confident after reading instructions give it a try, once again a preservative free dog biscuit soaked in warm water and blended to the thickest consistency that will flow through syringe.
roosters are strange creatures, whilst they can be very strong a lot of it is bluff, as well as being very injured, after nearly being eaten he is also depressed, keep on treating, if he doesnt give up, he will come round and either way you will have done the best you can.