One person tube feeding.

[Shadrach]

If you can figure out tube feeding or get a friend to hold the chicken while you tube feed it is much safer not syringing properly right into the birds mouth means you could actually get it down their windpipe and aspirate the bird. They could die... so if doing this way only do very very small amount at a time let the bird swallow or if you are confident in your chicken anatomy knowledge and ability to get is syringed far back enough over the windpipe hope. I don’t feel confident enough to do that so I have chosen to tube feed

As I mentioned earlier, the syrigne supplied with Metacam proved to be ideal for pureed food. It's thin enough and long enough to slide past the windpipe.