The Difference between Shell Grit and Oyster Shell for your Poultry Health

Unfortunately, a lot of people think that grit and oyster shells are the same things. They are not.  Your hens require both oyster shell and grit. Without it, serious health issues can arise, such as Sour Crop and Brittle Bones.

So now we know that our ladies need oyster shells and grit as additives to their diet, but why do they need them?

Oyster shell is exactly what it says; crushed oyster shell.  It is  high in calcium which is what our ladies need.

Oyster shell is also known as soluble grit. This is because it dissolves in the hen’s gut and is absorbed by the body and stored for later use in making shells or strengthening bones.  Even though we are told that a layer feed is complete and that the hens do not need anything other than the feed, it may not contain enough calcium for your hens.

Did you know that an egg is between 94-97% calcium carbonate? That’s an awful lot of calcium!  As with people, chickens are individual creatures so the needs of one hen may not be the same as her neighbors.

Some require more calcium as they are prolific layers, thers – not so much. Yet others may have a shell gland defect that requires more calcium than normal.

The best practice is to leave out a bowl of each item.  This way the hens can help themselves when they feel they need one or both items. Some people sprinkle oyster shells into the feed; this is not a good idea.  Too much calcium can lead to problems with the kidneys which can be deadly. Let the hens self-regulate, they will do what’s necessary for them.

It’s also best to let the hen self-regulate her grit intake. As we mentioned, a little grit can go a long way so the hen will be able to ‘top up’ when she needs it.

Grit and Oyster Shells Nutritional Value

Oyster shell has calcium which is a necessity for the hens. Not only does it ensure a good hardshell on the eggs, but it also ensures that the hen has strong and healthy bones.  A hen that has a very low calcium level can suffer from broken bones; most noticeably in the feet and legs from jumping up or down to perches.

Grit has no nutritional value in and of itself but without it, the bird would not be able to process food properly. The grit helps to unlock all the nutrients in the food by grinding it down to a thick paste.

Sour crop can be caused by insufficient grit in the gizzard. When a chicken eats, the food goes down into the crop for storage and later digestion.

When Oyster Shells and Grit Aren’t Necessary

Only laying hens require oyster shells; chicks, the older chickens, and roosters do not require any oyster shell added to their diet.

In fact, too much calcium can be detrimental to a hens’ health, so it is best to offer up an oyster shell in a separate container. Those hens that need it will take it, the others will not.

You can also feed eggshells back to the hens for extra calcium. I usually ‘cook’ my used eggshells in the oven for about 30 minutes after I’m done baking. I turn the oven off and set the shells on a tray.  This not only makes them easier to crush but will destroy any bacteria present.  Make sure you crush the shell well enough that they aren’t recognizable as eggs otherwise those smart hens might get some ideas and start eating eggs!

Chicken Grit: All You Need To Know - Why Do Chickens Need Grit? 

Chickens don’t have the means to grind or masticate their food since they don’t have teeth so they need something to reduce the food particle size to a manageable form.  The grit, after ingestion, travels down into the gizzard where it will stay for quite a while until it is worn down sufficiently to pass through the bird without causing harm.  Once it settles there, it goes to work helping the muscular gizzard to grind down the food into a nutritious paste from which the gut absorbs all the nutrients and water before eliminating the waste.

Without grit, the food would not be rendered into a useable form for the bird.  In fact, insufficient grit can cause things like impactations because the gut cannot deal with lumps of food – it just isn’t set up that way.

In general, the chickens’ digestive system is highly efficient, but without grit, it will come to a halt.  You should always provide free-choice grit for your birds; this means they should always have access to grit.

HANDY TIP: Oyster shell can also be used in the garden for many uses including protecting your precious seedlings from snails and slugs!

Shell grit and oyster shell provides the calcium that is used to make eggshells. Without a sufficient intake, hens are more likely to lay thin-shelled or soft-shelled eggs, and become prone to internal egg breakages and becoming egg bound. Calcium is also used in many other processes inside the hen’s body. It functions in association with a smaller amount of phosphorus, and these can only be utilised in the presence of vitamin D3. Protein is also required to facilitate the process. This is why a balanced diet is a must for chooks.

Where there is a shortfall in dietary calcium, hens must call on reserves in their medullary bones, in the sternum, pelvis and legs. Over time this can lead to the skeleton being compromised and stress fractures can occur. Avoid this by supplying fine or medium grade shell grit. The grit is retained in the glandular stomach where it is dissolved into the blood stream and utilised to make the eggshell.   

Don’t quit on grit!

Let the chooks help themselves to shell grit rather than mixing it in with food. This allows them to access it at the right time for optimal absorption to make the shell. Most hens prefer to peck away at it in the mid afternoon, ready for the 18-hour shell formation process that occurs overnight. A constant supply also means hens laying at different rates can choose the exact amounts they need.

Bottom line is your laying hens require free access to shellgrit for strong and healthy egg laying.  We offer three grades of shellgrit - fine and medium grade shellgrit in a handy 5kg bag or 20kg bag, along with our budget mixed shellgrit in 5kg and 20kg.  Shellgrit should be offered in a separate feeder to your layer pellets or grain mix and needs to remain clean and free of debris.