The Best Shell Grit For Chickens and How To Use It

Chickens don’t have teeth, but they do have a gizzard. Chickens need access to grit at all times, it’s an important part of their diet and overall health. Now when I say "grit", there are two types of grit. Soluble, such as shell grit or crushed oyster shell both offer a slow-release of calcium, whereas insoluble grit such as tiny rocks, pebbles and sand aids digestion.

How to use shell grit
I'm a big fan of "free choice feeding". This means that I don't mix shell grit into my chickens' feed, but rather, allow then to self-serve and choose when they need supplementing.

The easiest way to supply shell grit to your hens is to put it in a small 200ml plastic or ceramic bird-cage feeder, hooked to the side of their coop or run, at the same height as their back. This will stop it from getting dirty. Smaller amounts changed or refilled more frequently works best. Chickens like their shell grit clean and sparking. "Girls like diamonds and your hens are no different!" says Australasian Poultry Magazine's Megg Miller. "Keep it clean. Replace or add a little water and stir if it's losing its lustre".

What is shell grit exactly?
Shell grit is literally tiny whole and broken up sea shells. It's 100% real and natural, and can be found on the shores of lakes and coastlines across Australia.

Shell grit varies in look and texture, depending on where it's sourced. It can be very fine, consistent and almost white, all the way to being very coarse mixed shells. Most of the shell grit in Australia that's perfect for poultry comes from the pristine shores of South Australia, and is a combination of both. It's graded and sifted by size. The medium grade is perfect for laying hens and pullets, as well as ducks.

The coarse texture is great for Geese and Muscovy ducks and the fine textured shell grit is more appropriate for small birds. 

Why is shell grit so important for chickens? 
It helps them digest food and is a great source of slow-release calcium; critical for bone health and strong egg shells. When chickens don't get enough calcium from their diet, they draw it from reserves in their bones. 

What sized shell grit should I be buying for chickens?
Medium sized shell grit is what you should be buying if you're in Australia. The finer the shell grit the faster and more easily it is absorbed, however, what we want is for the hen to still be accessing and digesting the shell grit when she's retired for the evening to the perch. Medium shell grit takes longer to get through the upper digestive tract, which allows for a slower release of calcium around the clock. This means your hen is taking less out of the calcium bone bank when creating an egg shell. 

What is the difference between Shell Grit and Oyster Shell?
Ground up oyster shell and shell grit are both soluble grits, and have the same function in regards to poultry. Oyster shell tends to be more common in the US and the UK, whereas shell grit seems to be more common and accessible in Australia. So essentially it depends where you're getting your information from! 

Do you really need to offer insoluble or hard grit to your hens?
Fowl that free range will naturally find and peck at tiny rocks, pebbles and large grains of sand. These are insoluble grit and aid digestion by assisting the grinding of food in the gizzard. 

I know many people who do not offer their hens insoluble grit, including some free range farms. Until a couple of years ago I thought I was covering the use of hard grit by using shell grit. Two birds, one stone! However, when I asked two of Australia’s best Old English Game breeders for their thoughts on grit, both were quick to correct me and emphasise the importance of insoluble grit. “When you think of size (of grit), think road scrapings, fine gravel…” was one breeder’s tip. Given that these two men have very hardy, quite disease resistant flocks, I’ve taken on their advice.

Do I need to feed shell grit to chicks and growers? 
No. Chicks and growers up to 16 weeks benefit from insoluble grit (coarse sand, tiny (tiny!) rocks and stones etc, but not calcium-releasing grit such as shell grit. Offering small amounts of whole wheat grains from day 10 can also assist the activation of the digestive tract. Calcium requirements of pullets increases dramatically when they commence laying... they've got to put a shell on that egg!

Do I need to feed shell grit to roosters? 
Roosters will still peck at shell grit, but their requirements are far less. This is why I prefer to offer shell grit as "free choice" instead of mixing into feed; this allows them to supplement as required. 

Why not just feed hens a calcium supplement?
Whilst the calcium-magnesium balance is applicable to dogs, cats and livestock; it is calcium and phosphorus that are the important elements to balance in poultry. Excess calcium in poultry can inhibit phosphorus, as well as lead to kidney damage, soft bones and, according to Damerow (1994) a susceptibility to parasites. 

Slow-release calcium is what your hens want. So stick to a balanced diet supplemented with shell grit or oyster shell. 

Where to buy shell grit in Australia
Below is my Australian medium shell grit, perfect for laying pullets and hens: 

Shell grit for chickens Australia 

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