Crop Stasis

Crop stasis is a condition which occurs when the chicken's crop doesn't empty at a normal rate. It is a clinical sign of a disease, rather than a disease itself.

The crop is a round-shaped out-pocketing of the chicken's esophagus. It is located at the base of the neck (it may be easier to locate when it's contents are full, which is most likely to occur at the end of the day). The crop acts like a temporary storage pouch for food, and is where the initial stages of digestion occurs in chickens.

Normally, when chickens ingest food, it should only remain in the crop temporarily, before moving through to the proventriculus (referred to as the glandular stomach, where digestion primarily begins), and from there through to the rest of the gastrointestinal tract. The movement of the food through the digestive system is referred to as gastrointestinal motility, and is controlled by highly coordinated waves of contractions.

Any disruption in the gastric motility, or obstruction of the intestinal tract will eventually cause food to back up into the crop. If the food remains in the crop, it will start to decompose and cause sour crop.

There are several reasons why chickens develop crop stasis, which include:

• Crop impaction: May be caused by eating tough, fibrous vegetation (such as that from grass clippings), long pieces of string or baling twine, or certain potted plants.
• Decreased or impaired gastrointestinal motility : May occur during really high environmental temperatures, when a chicken goes a long time without feed and then eats too much too quickly when feed is available again, Marek’s disease, or heavy metal poisoning.
• Gastrointestinal (GI) Obstruction: GI impactions can occur from ingestion of fibrous plant material (such as long pasture grasses), compacted feed, miscellaneous ingesta (tortilla pieces, baling twine, soft plastics, wood shavings, etc.), tumors, or by high loads of intestinal parasites.