Why do Chickens need Grit and Oyster Shell?

In order to digest their food correctly, chickens require fine (insoluble or ‘flint’) grit. Of course, chickens don’t have teeth (remember the saying “as rare as hen’s teeth?) so they use this grit to grind down their food.

A diagram of the digestive system of a chicken shows the path food takes. Inside the proventriculus, food is mixed with acids and digestive enzymes. Grit accumulates in the gizzard, which with a strong muscular action, grinds the food down. So to digest their food correctly, chickens need insoluble grit.

If your hens are allowed to free-range then it is likely that they already get enough grit in their diet however, this is not always the case because it depends on the type of ground they are kept on. It is cheap enough to buy so it’s easy to provide some in a hopper like the one shown here, just to make sure they are getting enough.

Soluble Grit

Oystershell-GritSoluble grit (the most common being Oyster shell grit) often gets confused with flint or insoluble grit.

Soluble grit is digested by the hen and contains calcium, most of which is used to form strong egg shells. The majority of an egg-shell is made up of calcium carbonate and a constant supply of oyster shell grit ensures they have sufficient calcium in their bodies.

If sufficient calcium isn’t available, hens can lay soft or poor quality shelled eggs.

grit-hopperGrits can be mixed together, or provided in separate containers. A container that keeps the grit away from the floor to stop them kicking muck into it is ideal. The container shown here is galvanised and is topped up every couple of months, supplying a flock of 20 hens that are able to free range. It is fastened to the inside of the hen-house so that it is kept dry during wet, windy weather.

If you’re on a budget, you can make a grit hopper out of a plastic flower-pot. Bury half of it in the ground and peg it down with a piece of stiff wire through the holes in the bottom. Top it up with grit. When it rains, it will be able to drain freely through the holes.

As an alternative to oyster shell grit, baked crushed egg shells can also be used since they are mainly calcium carbonate too. Hopefully you will have a good supply of egg shells!

Chicken feed containing grit

Some feeds include a mixture of grit and oyster shell in them for example, The Smallholder Range – Super Mixed Corn or BOCM Layers pellets found in the UK.

Remember this when pricing up your feed –  although bags of feed containing grit appear cheaper, grit is of course heavier and cheaper than layers feed so it’s not a fair comparison.

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Tim Daniels

Tim is the founder of the poultrykeeper website and lives in Herefordshire, UK. He keeps Cream Legbar chickens, Silver Sebright bantams and hybrid layers for eggs, Abacot Ranger ducks, Brecon Buff geese and some quail.

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