I often read comments from people indicating some confusion in understanding the difference between chicken grit and oyster shell. Oyster shell and grit are two different products that accomplish two different things, and they are NOT interchangeable. Let’s take a look at the two products and their purposes.
Grit
Chickens don’t have teeth! When a chicken eats, they pick through food with their beaks, decide what looks good, and swallow it. Sometimes they swallow so quickly, I wonder if they even know what their food tastes like! As food travels through a chicken’s mouth, it is mixed with saliva and some digestive juices to start the digestion process. The food travels down the esophagus to a food storage compartment called the crop. You might notice a lump at the base of your chicken’s throat after they have eaten. This is normal. The crop can stretch to accommodate a good amount of food. Food can be stored in the crop for up to 12 hours. It appears that this is a survival mechanism for chickens. Since chickens are prey animals, this allows them to gobble up a lot of food, store it and digest it later.
Food is slowly released from the crop and it travels to the gizzard. The gizzard is the organ where food is actually broken down. The chicken consumes small pieces of rock and sand, called grit, which sit in the gizzard. These small pieces of rock work like grinding stones, and they along with digestive juices and the muscular action of the gizzard cause food to be broken down into usable particles. The ground up food then passes on through the small intestines where nutrients are absorbed into the body. As grit is worn down, it will be expelled and the chicken will need to consume more grit. A chicken who is not provided with sufficient grit can suffer from nutritional deficiencies and even intestinal blockages. Impacted crops and intestinal blockages may require veterinary intervention, so prevention is the key.
If your chickens are able to free-range or have access to a yard and dirt, they can pretty much take care of finding grit for themselves. For birds that are caged or don’t have access to small bits of rock and pebbles, grit needs to be provided for them. Again, grit is just ground up or small pieces of rock. Prepackaged grit is available at most animal feed stores and is fairly inexpensive, or you can prepare your own. If preparing your own, inspect the dirt to make sure there are plenty of small rock particles.
For young chicks, their starter feed is ground small enough that they don’t need grit. However, once you start supplementing their starter feed with treats, oats, herbs, or fresh produce, it’s time to begin giving them grit. They do make a chick grit that is specially formulated for small gizzards. Chicks under 10 weeks of age should be given the smaller chick grit.
Providing grit is easy. It should be available at all times. It is simple enough to keep a container filled with grit inside the coop. It is insoluble so it won’t dissolve or melt. I’m lucky in that my chicken run is dirt and contains lots of small pieces of grit. I do, however, introduce my chicks to fresh produce and chopped up oats, so I make sure that I provide them with grit. I believe they instinctively know that it’s something they need.
Oyster Shell
Oyster shell is simply a form of calcium carbonate, a chemical compound that chickens require to form strong eggshells. A calcium deficiency in a chicken’s diet will likely result in soft or thin shelled eggs and the possibility of rickets or even osteoporosis. If your hens are of laying age and your flock consists of only hens, then it’s fairly easy to make sure they are getting adequate calcium in their diet. Just feed them a quality, brand name layer feed which contains calcium. Be sure to read the labels and don’t just assume a layer feed has calcium. You can also offer free-choice calcium carbonate in the form of oyster shell, limestone or recycled egg shells.
If you have a mixed flock as I do, it becomes a little more challenging. Too much calcium for young birds and roosters can cause health problems such as kidney disease. It can also have ill effects on non-laying ducks and geese. In this case, you can feed your birds a good mixed flock feed or meat-bird feed that does not contain calcium. and provide a free-choice calcium supplement. This way the birds will only consume the calcium that they need. Laying hens seem to instinctively know when they need calcium. If you offer some form of calcium carbonate free-choice, your hens will eat what they need and the birds that don’t need it won’t be forced to eat it in their feed.
You would be surprised at what other foods are a good source of calcium. The sage herb offers 33mg of calcium. One cup of dried sunflower seeds in the hull contains 35mg of calcium. One cup of red wheat has 56mg of calcium and 24 grams of protein, white wheat contains 57mg of calcium and 18 grams of protein. So wheat is a good source for both protein and calcium.
Calcium carbonate is the most common form of calcium found in nature, making up limestone, coral reefs and seashells. An egg shell is made up of calcium carbonate and small amounts of protein. The kicker here…a 1/2 teaspoon of crushed eggshell offers 1,000-1,500mg of calcium‼ I guess that’s another way our chickens give back! I used to just throw all my eggshells in the compost bucket, but not anymore! I wash the eggshells inside and out, set them on paper towels to dry, then crush and serve! It’s that simple. And they are free!
The important thing to remember here is that calcium carbonate is water soluble, it dissolves, and can not act as a grinding agent in the gizzard. Even though oyster shell may look similar to grit, it is not the same and is not able to perform the same job that chicken grit performs. Chicken grit and oyster shell are two different products, have different purposes and are not interchangeable. Chickens need both in their diets to maintain good health, strong egg shells!
