The gullet is a bird's esophagus, which begins at the back of the throat and leads to the crop. The crop holds the food waiting for digestion. After your bird has eaten, you can feel the crop below the throat in the breast. For a chicken, the crop is usually about the size of a golf ball. It should feel firm and round when it's full.
If your bird acts listless, has a full, hard crop, is not defecating, and refuses to eat, it may have an impacted crop or gullet. This condition can be serious, leading to infection, starvation and death if the blockage is not removed. Feel the crop right before your bird goes to sleep for the night. It should feel pretty full, since most poultry will fill up and digest during the night. Remove your chicken's food source and check the crop first thing in the morning before feeding. You shouldn't be able to feel the empty crop. If your chicken's crop is still full and hard, it's likely that food is not moving into the digestive tract.
Emptying an Impacted Crop
Gently massage the crop with your fingers. Massaging the crop can help loosen the food and help it move down the digestive tract. Olive oil can help move things along as well. Use a few teaspoons in an eye dropper and carefully insert it about an inch or two down the bird's throat. Enlist a friend to help, as you don't want to push the oil into the chicken's lungs if she struggles. Massage the crop to distribute the oil, and wait until the next morning to see if the crop empties. If it's still very hard or your chicken is very listless or losing weight, a veterinarian can surgically remove the contents. Offer water only until the surgery is done. Chickens can live about a week without food.
This condition can develop when food remains in the crop or gullet for more than 24 hours due to a blockage. After that amount of time has passed, the food begins to ferment and go rancid. Your bird may have a large, squishy feeling crop with a bonus of bad breath. You might be able to smell it just by holding your chicken, but if you open her beak and take a sniff; you'll know right away. Use the same remedies as used for an impacted crop: massage and some oil. You can also try to turn your chicken upside down and rub the crop in the direction of the mouth to get her to vomit up the contents. This second remedy is best performed under the supervision of a veterinarian to help prevent the contents from entering the lungs.
Preventing Digestive Disorders
Long blades of cut grass or tough fibers tend to form a mass in the gullet and crop that can cause a blockage. When chickens graze on grass they take small, measured bites. Keep living areas free of foreign objects that your birds could eat, such as plastic, string or rubber bands. Provide lots of fresh water. Adding unfiltered apple cider vinegar to their water will lower the pH in the crop and help prevent bacteria growth. A weekly treat of plain yogurt promotes the growth of beneficial bacteria in the digestive system. Most crop impactions occur due to overeating quickly after being deprived of food. If you have any concerns about your chicken's health, consult your veterinarian.