Here's some info that's probably already been posted on here a hundred times but I can't seem to find....
LINK:
http://club.omlet.co.uk/forum/viewtopic.php?f=41&t=5334&p=143934
Before you can decide if your hen is unwell because of a crop problem you need to know what a normal crop should be like.
Hens only have a small gizzard (stomach) for grinding up their food which is quite a long process for them as they have no teeth to chew it up first. The food eaten during the day is stored in their crop which will gradually become distended. They can eat so much they become quite bosomy in a singular sort of way. During the night they will gradually grind the food up in their gizzard and their crop will become deflated by morning. If the hen has a lump on her chest in the morning feel it to try to determine what the problem may be.
Blocked or Impacted Crop
If the lump is hard, then it is called impacted or blocked crop. This can happen when they have eaten long, tough, fibrous grass, or something similar, and it has got into a tangled mass that is too large to pass further down.
Some Omleteers recommend giving the hen live white maggots (the fishermans type) to eat. These may then eat their way thought the blockage. A more standard treatment for a blocked crop is adding a lubricant and massaging the crop to try to help break up the blockage the contents so it can pass out of the chickens crop and on down into the digestive system. Do not try to make your chicken sick as the hard lump will be too big for the hen to regurgitate !
Olive oil is good option as a first aid measure, but do not to use it for more than a day or two, as it may overload the chickens liver. Another option is liquid paraffin (from chemists or vets) which, does not go through the liver passes out with the droppings.
Use 2-3ml of oil or liquid paraffin twice a day, and massage the crop quite firmly for a few minutes afterwards. Use a syringe to give the lubricant, being careful to put it past the hole at the back of the chickens tongue. This hole leads to the lungs and if anything other than air gets down there this can be dangerous. You may need to use a syringe with a narrow tube attached.
Avoid letting the chicken eat anything which might add to the impaction. Feed soft, highly nutritious food. If this treatment does not reducing the size of the lump, or has not resolved the situation after a week, or the chickens health is deteriorating in any other way, the only other option is to consult your vet.
Sour crop
If the crop is very soft and feels like a water filled balloon, then this is called a sour crop. This is caused by a fungal infection and all the extra liquid is the bodys reaction to the fungus. In this case the crop contents will smell awful, so another way to confirm this is the problem is to smell the chickens breath, which can be done at anytime of the day. A bad smell points to sour crop. Sometimes a hen my regurgitate some of the contents of the crop.
You can get rid of some of the fluid by making the chicken sick. If you do this you need to be very careful so the chicken doesnt choke as the fluid comes back. You should hold her upside down away from you, head downwards, and gently pushing with your hand from the bottom of the crop upwards towards the chickens head. Do several small attempts, rather than one big one.
Then feed you hen live, bio yogurt. Most chickens, given the chance, will eat this directly. If she will not eat it give a teaspoon or two (5-10 ml) by syringe daily. And feed soft nutritious food. If this treatment does not help after a few days, or if the chickens health is deteriorating in any other way, a vet will prescribe an anti-fungal medicine. If sour crop is left undetected or untreated long term there can be irreversible damage to the lining of the crop.
Putting Apple Cider Vinegar in the drinking water and garlic in their feed are very good for the digestion and can help to prevent problems.
(MY COMMENT: Garlic makes the eggs taste funny!)