If you’re new to chicken keeping, you might be confused about two products you have read about or seen on your feed store shelves: oyster shell and grit. While many use these two products interchangeably, each actually serves a very important, and very different, purpose for your chickens’ well-being.
Let’s start with grit. Chickens don’t have teeth to help them chew their food. Instead, everything they eat is stored in their crop, and then in their gizzard, where it is held until it can be ground up and partially digested before it moves to the chicken’s stomach. Chickens allowed to free range will continually pick up small stones and coarse dirt which will help to grind up the food in the gizzard.
If you can’t let your chickens out to roam and find their own grit, then you will need to provide commercial grit for them. When they are chicks, a special smaller
sized grit, such as Manna Pro Chick Grit, should be provided to them free-choice in a small dish inside the brooder. Adult chickens should also be provided access to grit in a separate dispenser or feeder. That way each can eat as much or as little as she needs.
The grit is expelled as the stones and pebbles get smaller and smaller and new ‘grit’ needs to be ingested. If the grit you provide is too small, the pieces will pass right through the chicken’s digestive system and be of no help in digestion, so offering the correct size for chicks, pullets or adult hens is important.
Now a bit about oyster shell. Crushed oyster shell, such as Manna Pro Oyster Shell, provides calcium to your flock. Chickens need even more calcium than is included in even top-quality chicken layer feed because they use so much calcium to form the shells on their eggs day after day. If a chicken doesn’t get enough calcium, she will start to leach the calcium from her bones in order to create egg shells. That can lead to weak, deformed or broken bones. Not providing your chickens enough calcium can also lead to soft-shelled eggs, which are exactly what they sound like: eggs with a soft shell or no shell.
Calcium is also what produces the contractions in the hen’s oviduct which pushes the eggs out. Chickens who don’t get enough calcium and lay soft shells are in great danger of suffering from becoming egg bound, which is a potentially fatal condition caused by an egg getting stuck in the oviduct. If the egg breaks inside the hen, the shell (if there is one) can puncture her intestine leading to peritonitis. An infection that can be fatal if not treated.
Calcium should always be provided free-choice like the grit. This allows each hen to eat as much or as little as she needs. Some chickens don’t absorb dietary calcium as well as others, so each has different supplemental calcium needs. In addition, feeding the calcium free-choice instead of mixing it into the feed will not only save you money because non-laying hens and roosters won’t eat any, you won’t be overfeeding those that don’t lay eggs and therefore don’t need additional calcium. Any excess calcium is stored in their bodies and can lead to kidney problems over time.
An alternative to purchasing commercial oyster shell is drying and crushing eggshells to feed back to your chickens Just be sure to only ever feed your own eggshells to your flock, and crush them into small enough pieces that they don’t look like eggs any longer. This could tempt your chickens to experiment and start eating their own eggs. As long as you crush the shells though, you shouldn’t have any problems.