Understanding a Chicken's Digestive System & Crop Function

Chickens are active creatures, always pecking at something they've found on the ground and chasing flies and other insects around a yard. They can be extremely funny to watch and at times can even achieve some acrobatics reminiscent of few ballerinas. However, hens, cockerels and other poultry are also prone to certain illnesses which if left untreated can become serious health issues for the birds.

Chickens like other birds have very different digestive tracts to that of a human and just like people, they can suffer digestive issues which can make chickens very poorly, sometimes it can even prove fatal.

Chickens scratch around in the ground and when they find something they like, they take in their beaks ready to be swallowed. This food then makes its way down the esophagus to the bird's crop where it's not only stored but rendered moist too. A chicken's crop has a specific function which is to sort food out like a holding tank.

When the food is ready and sorted out in the crop, it passes into one of the two stomachs that a chicken has. The food either goes into the proventriculus or the gizzard. The “easy” to digest food goes to the proventriculus where it's broken down by hydrochloric acid as well as digestive enzymes. Food that's harder to digest and which needs to be “mechanically” broken down passes to the gizzard to be processed - this is where muscular contractions combined with some small stones (grit) are needed to process any food that's ingested.

Three Crop Problems to Look Out For

After the food has been fully processed it then passes into the bird's small intestines where it still gets processed through the rest of the digestive tract. Occasionally, something happens in a bird's crop which causes a real problem for the chicken to digest their food – sometimes it is so bad, the bird can't digest any food at all. There are three common problems that occur in the crop which are as follows:

• Impacted crop
• Sour crop
• Pendulous crop

There are certain signs to look out for should a chicken be suffering with a crop problem which include the following:

• Weight loss
• Lethargy
• Difficulty turning their head side to side
• They prefer to be on their own

Impacted Crop Explained

A chicken's crop is found in the middle of the bird's upper chest. When the crop is full, it should feel nice and firm to the touch, and a healthy crop should be around the size of a plum when full. Chickens go to bed with nice full, firm crops and by the morning, they should be empty. An impacted crop will stay firm and can get as large as a tennis ball and a little tender.

What Causes an Impacted Crop?

There are a few reasons why a chicken may suffer from an impacted crop and these are listed below:

• The chicken has eaten long grass, straw or hay
• Chickens will eat foreign objects and this includes plastic, rubber bands and metal which may cause an impaction
• A fungal or bacterial infection
• The chicken may have eaten a big or tough piece of food
• The chicken may be suffering from a pendulous crop (see below)

​​The Best Treatment for an Impacted Crop

You need to make sure the crop is empty first thing in the morning before the chicken has a chance to eat anything. If you find the crop feels firm, tender and as large as a tennis ball, the chances are it's impacted. The first thing to do is isolate the chicken into a large cage – a dog cage is perfect.

The only treatment is to try and empty the crop by gently massaging it with your fingers just as if you were kneading dough when making bread. If you're lucky, this might be enough to get things moving but you may need to do this a few times a day over a couple of days always being as gentle as you can.

You can feed you chicken but you should only offer them a little soft bread that 's been soaked in olive oil but you need to take the crusts off. The oil will act as lubricant which should help to empty the crop. You need to make sure the chicken has access to plenty of grit and to avoid feeding any treats which includes seeds, fruit or vegetables until their crop is working properly again. This is because these are the hardest things for them to digest. Clean water should be given to the sickly hen at all times.

If after a few days, there is no improvement then you would need to contact your vet and seek advice from them. The one thing you should avoid doing is trying to make the chicken “sick up” anything in their crops as this could quite easily kill them. The reason is that any fluid may get into their lungs and ultimately this will suffocate the bird. If the cause of the impaction is a fungal infection, your vet will advise on treatment and medication.

Sour Crop Explained

When the crop takes too long to empty, this can result in a condition known as sour crop. Food sitting in the crop will start to ferment and this causes a yeast infection (fungal) to develop. When a chicken is suffering with a sour crop it will have what can only be described as a “boggy” feel to the crop which will be large but not firm to the touch as with an impacted crop. You may even hear a gurgling noise when you gently move the crop around. The chicken's breath will smell quite fermented and “yeasty”, not a pleasant aroma at all, and the crop will be quite tender to the touch.

What Causes Sour Crop?

There are several reasons why a chicken may suffer from sour crop and these are listed below:

• Crop not emptying correctly
• Impacted crop could be partial or complete
• Recent use of antibiotics which can cause a secondary infection
• Fungal infection
• Worms may be slowing down the rate of digestion

The Best Treatment for an Impacted Crop

It can be quite hard to treat sour crop without the correct veterinary medicine. Chickens with the condition usually need to be given a week's course of some kind of prescribed anti-fungal medicine. But you would need to find out what the underlying cause of the condition is in order to treat it correctly. This means making sure your chickens are regularly wormed and always checking their crops on a regular basis too. Feeding your chickens probiotics will also help avoid the problem – plain yoghurt is particularly useful.

Pendulous Crop Explained

Just occasionally, muscles in a chicken's crop get damaged and this could be due to having suffered an impacted crop or from eating very “heavy” food. If this happens, the crop when full dangles down towards the ground and may even sway from side to side. You need to make sure the crop is emptying overnight or it might lead to the bird suffering from an impacted crop making the problem even worse.

How to Treat a Pendulous Crop

The best way to cope with a pendulous crop is to just allow the bird to drink water for a period of 24 hours and no food whatsoever so the crop gets to rest. After this you should give the chicken some regular feed always making sure there is plenty of grit available to them. You need to avoid giving the bird any treats like seeds, fruits or vegetables until the crop is working properly again. If you find the crop is not emptying overnight, then you seek the advice of your vet.

Tips on How To Keep a Crop Healthy

• Make sure chickens have access to grit at all times
• Avoid feeding chicken large hard to digest food
• Add apple cider vinegar (1 tablespoon per gallon) to their water supply
• Avoid using metal water containers that may rust
• Feed your flock plain yogurt with live and active cultures to help promote the good gut bacteria
• Add probiotics to feed
• Avoid feeding chickens sugary human food
• Inspect chickens crops regularly
• Keep grasses short where the chickens free range (2 inches max)
• If your chickens like to eat straw and hay, avoid giving it to them