This is from the help pages. I cannot remember who wrote it. Some people just tilt the bird backwards, and massage the crop twice a day. Then be sure to give him some yogurt. Please remember that hanging upside down is not good for long periods. They cannot breathe properly, and roosters are more susceptible to suffocating. Don't worry overly about it. I am just putting a bug in your head to get it done in a timely manner.
[Sour Crop] is a common problem with hens, especially if they are allowed to graze on grass when they are first released. These birds are not used to eating such natural foods, so they tend not to know how to do it properly. Long strands of grass in the crops of such birds often are unable to pass through the digestive system, [so they] bind in the crop and ferment.
A quick method of telling whether a chicken has Sour Crop or not is to gently squeeze it and sniff the air that’s expelled from its mouth. If the bird has Sour Crop then the air will smell awful, if not… well, I don’t suppose a chicken smells very nice anyway, but apparently la différence d’odeur is marked. (Of course, sniffing chickens is also one of the eight sure-fire ways of being marked down as a loony, but we’ll put that aside for the moment.)
Fear not, help is at hand (If you were a chicken)
Luckily for you my mother has a cure for Sour Crop. First she grabs you (this isn’t hard because you’re just lying there burping), then she sticks a tube down your throat, and pours a mixture of yogurt and olive oil into you.
That done, she takes hold of your feet, hangs you upside down, and massages your stomach and crop until lots of green and white muck comes pouring out of you.
Finally she flips you the right way up, pats you on the head, and puts you down. You ruffle your feathers, squawk a bit, ruffle your feathers some more, and then walk off in as dignified a manner as you can muster.
It’s a tough life, being a chicken.
