Thanks! He is in solitary confinement right now, to try to get him to eat more.
Priscilla, one of my two Brama hens, was attacked by a raccoon. She fought back and survived. She has lacerations along one side that required (many) stitches and a dressing. She was put under anesthesia for the surgery. Her beak was terribly damaged in the attack. She is unable to eat on her own. She was noticibly in shock for the first couple of days, as well. Her vet attempted to make a prosthesis for her lower beak using superglue and wire for alignment. It has now been 2 weeks since the attack. Prissy is being kept in an "infirmary" cage inside our house and fed via syringe and tube to her crop. I feed her at least 3-times daily, about 50 ml per feeding of a homognized gruel made of scrambled egg and chicken feed with electrolites. Approximately 50% of the mix is water to enable flow through the syringe, but also to assure that she is well hydrated. Priscilla is vigorous, poops normally and, although I think she did have a fever, appears normal now. She gets pain med and antibiotic daily, powdered and mixed with the food. The prosthesis fell off 2-days ago, suggesting to me that her lower beak part is growing. The upper visibly is growing.
For your rooster, definitely you should be feeding him as I described for Priscilla. It really takes two people do do the feeding. We swaddle her in a towel to constrain wing movement, and provide a leg or arm for her to perch upon. Then, I hold her head and insert the feeding tube. Be oh, so gentle! And go S L O W. I use water soluble personal lubricant on the feed-tube. Your boy does need isolation, and a relatively warm, comfortable surrounding for several weeks, at least. Hold him, talk to him, stroke his feathers, change bedding (we use puppy pads) regularly -- like, daily! And keep his mouth clean.
In my case, I thought Priscilla was IN the coop when I closed it up for the night. Big mistake! I screwed up, and Prissy always likes to roost outside the coop. So, I'm doing all that I can for her, and she seems to be thriving. In the mornings when I open her cage, she walks to the kitchen for feeding. Chickens DO have intelligence and can be trained. She doesn't LIKE the tube, but she tolerates it pretty well. Her weight has stabilized and even increased a little.
Some of you know I'm writing stories about our flock. This encounter will be another one. "Mrs. Doolittle and the brave little chicken."