Grit for Chickens: When in Doubt, Put it Out

Oyster Shells for Chickens Provide a Key Nutritional Supplement for Egg Layers


By Tiffany Towne – It’s hard to make an argument against using grit for chickens, along with oyster shell supplements. They’re both fairly inexpensive and a little lasts a long time. But from a nutritional viewpoint, the stakes are much higher. These two supplements (yes, they are two very different things) are essential for healthy birds and maximum egg production.

It’s always a good time to review what to feed chickens and why you should make grit and oyster shell supplements available free choice — in separate feeders — all the time. According to Twain Lockhart, a poultry consultant for Nutrena brands, “It’s better for birds to have continual access to grit and oyster shell and not need them, than to need them and not have them.” Here’s why.

Grit for Chickens and the Gizzard

From beaks to vents, chickens have one of the most efficient digestive systems in the animal kingdom. Very little of what they eat goes to waste, despite the fact that they have no teeth. Instead, they swallow tiny rocks that end up in their muscular gizzard. Food that mixes with these pebbles is ground up as the gizzard contracts, breaking food particles into tiny specks the bird can digest. Lack of grit can lead to digestive blockages, poor feed conversion, discomfort, and even death.

Who Needs Grit?

Generally, hens exclusively eating commercial feed (think caged production operations) don’t need grit because the feed quickly dissolves in their digestive tract. But as soon as chickens get other types of feed, they need grit to break it down so the gut can absorb it. Grit is essential for any bird consuming large particle-sized feed (grains, grass, weeds, etc.). The same goes for birds that are confined to a coop and given any scratch, grain or kitchen scraps.

Biggest Myth of Grit for Chickens

Many people think free-range birds don’t need grit. False. Grit should be available even to free-range chickens if there is any chance they can’t find natural grit materials in their surroundings. (For example, areas with clay soils, lack of small gravel particles, heavy snow cover or grass pastures.)

How Much Grit for Chickens

It’s best to give birds free access to grit. They’ll take what they need for proper digestion. Feed stores sell insoluble grit for this purpose. NatureWise poultry feed now offers 7-pound bags of both oyster shell and grit, which is enough to last a small flock all year. The grit is a mix of two particle sizes, so it works for smaller birds and standard breeds.

When to Start Grit for Chickens

Start chicks on grit once they leave the brooder and are introduced to outside forage and feed sources that are not solely a pellet or crumble (grass, greens, bugs) and/or once you start feeding scratch or any grains.

Lay on the Calcium

Laying hens require much more calcium (three to four times) in their diet to support laying and to create eggs with hard shells. Feeding layer feed will keep laying hens healthy and productive. But extra calcium is essential to help prevent thin eggshells, birds that eat their own eggs, and prolapse. Eggshells consist primarily of calcium carbonate, the same material found in oyster shells. Likewise, calcium supplements are typically ground-up oyster shells or natural calcium stones. These dissolve in the hens’ digestive tract and add calcium to their diet.

Who Needs Oyster Shell and When?

All laying hens should have access to a separate container full of crushed oyster shells. Begin feeding free choice when pullets come out of the brooder.

Biggest Oyster Shell for Chickens Myth

Like the grit myth, many people think feeding a high-quality layer feed means an oyster shell supplement isn’t needed. False – even the elevated amount of calcium in most layer feeds might not meet the daily requirements for all hens at all times.


How Much Oyster Shell

Give birds free access to oyster shell and they’ll take what they need, based on age, diet, breed, stage of production, etc. Older hens, for instance, need more calcium than younger hens. Hens on pasture obtain some amount of calcium naturally, but illness in the form of sick chicken symptoms may cause a calcium imbalance. In warm weather, when all chickens eat less, the calcium in a hen’s ration may not be enough to meet her needs. On the other hand, a hen that eats extra ration in an attempt to replenish calcium gets fat and becomes a poor layer. The solution is simple. Put the ground oyster shell in a small dish or sprinkle it on the coop floor for hens to discover and eat. If you are feeding a layer-specific feed along with oyster shell as a source of supplemental calcium, you should be covered, assuming all birds have access and can get their full requirements of feed and oyster shell.

One Final Myth Debunked

Despite all the information available, there’s still some confusion that grit for chickens and oyster shell for chickens are the same thing, and you don’t need both. Not so! Oyster shell is soluble in the digestive tract. It dissolves after a period of time and the calcium is taken up. Grit is insoluble and will stay in the crop (a pouch in the esophagus used to store food temporarily before moving it to the stomach) and help with digestion without dissolving. Remember, when it comes to grit and oyster shell, if you’re wondering how much should I feed my chickens, the general rule is: when in doubt, put both out.

Originally published in 2013 and regularly vetted for accuracy.

  • First L.

    I thought grit went into the gizzard, not the crop, as stated in the last paragraph.
    I’ve never cleaned a crop but I’ve cleaned a lot of gizzards and the gizzards had lots of sand, gravel etc. in them.

  • Catherene C.

    When I first got my original chickens July 2015, they came with some feed, oyster shell and grit in partially empty bags. I fed them what was there until gone. They were housed 80% of the time in coop until the garden was done. I changed the feed from the store brand to Purina layena and since it was already fortified with calcium, I omitted buying oyster shell. With my new chicks each year since, I never have bought chick grit or adult grit. As soon as the chicks no longer needed a brooder, they were placed in a dirt floor transition coop. My older chickens and ducks prior had dirt floor coops with free access to a completely enclosed pens with dirt. Now all my chickens and ducks are housed in a wood floor coop with free access to a large fenced area. They’ve eaten all the grass so there’s only dirt left so they can scratch and peck at their leisure. Plus they are fully free ranged as my time allows (never done unless I’m home) and they have have access to the old barn (used to store mowing equipment and gardening tools) with dirt floor which gives them a nice dryer area to scratch and peck or take a dust bath. Inside barn looks like little bombs went off from all their digging. I’ve only lost one chicken, a hen, to an impacted crop and that was 2 years ago out of over 100 chickens and 12 ducks. She also had a bad wing injury caused by an aggressive rooster. None of the neighbors with chickens use grit but some do feed egg shells as a source of calcium.


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