The Science Of Feeding Grit To Poultry

Hi and welcome!
If you are going to raise your hens to be egg layers, then it is important you give them the right granite grit at the right time in their development. Chick grit from 1 thru 3 weeks old. "teenage " size grit from 4 thru 7 weeks old. Adult sized grit from 8 weeks and older. The right grit at the right time will not help them grow faster. It will help them develop a larger and better functioning gizzard. I have been studying this all week. Now the gizzard is vital to proper digestion of the feed. What this means to you is that when the hens reach laying age, their better quality gizzards will cause them to digest their feed better. This will increase your egg yield up to 20%. It also means your hens will eat slightly less feed per dozen eggs than hens raised without grit. Fascinating, huh? I thought so.
Not every grit will do There are a bunch out there. Grit has 2 functions. It helps grind the feed and it helps deliver calcium to the hen. So with a plethora of different grits wth different composititons out there, what should we choose for best effects. You wouldn't believe the large number of scientific studies done on that topic! But after all is said and done, the best combination once the hen starts laying is adult sized granite grit and also crushed oyster shells. The grit is for the grinding, the oyster shell is for the calcium. OS helps a little in the grinding but gets worn down too quickly by the acids in the chickens gizzard to use oyster shell for grinding alone. The granite has sharp edges which stay sharp a lot longer.
Now if you are raising broilers on all mash only you don't need to worry about grit. It will make a small difference but not enough to worry about. Except..doncha just love it when someone writes that?...except... if you are going to finish your broilers by adding whole grain to their diets. If you do that then you should also add adult sized granite grit to their diet at the same time. That way they will put on more weight in the same time during finishing than if you fed the mash and whole grains without any granite grit.
Did you know that if you put a hollow iron tube capable of supporting between 435 and 520 lbs. in the gizzard of a turkey, the gizzard will completely flatten it? That's the kind of force in that large bird. The gizzard of a chicken contracts about every 19-20 seconds.
I use Gran-I-Grit for my poultry. It is made by North Carolina Granite Company ( website). Comes out of the world's largest open air granite quarry. They have been making it since 1935. They make all three sizes. I get mine at Agway. About 10.00 for 50 lbs. . Learn more here:
https://www.backyardchickens.com/products/gran-i-grit-insoluable-crushed-granite
Best,
Karen and the Light Sussex
in western PA, USA

Quote: ...One might argue that the better they digest their food, the faster they grow.

Good on you for sharing the info though.

Best wishes.

chooks4life said:

...One might argue that the better they digest their food, the faster they grow.

Good on you for sharing the info though.

Best wishes.

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What I learned: There is a science to feeding grit. It is more than just supplying stones to birds to help grind their feed because they don't have teeth.

Many people have studied growth rate and grit. To some degree the studies bear this out. However, the difference of rate of growth was so small as not to make feeding grit financially feasible during the growing stages, simply for growth's sake. In broilers, during the finishing stages, feeding insolvable grit with mash and hard grains resulted in significant gains in weight, well worth the adding grit. Feeding mash only with grit during finishing did not result in same weight gains. So it seems the grit was enabling the better digestion of the whole grains , resulting in better weight gain in the finished broilers.
Grit's worth is 2 fold ( 2 very important folds).
1. It helps develop a bigger healthier , stronger gizzard for the laying hens ( don't so much care about this development of a better gizzard in the broilers because they are being butchered anyway. The stronger, healthier gizzard in the laying birds helps digest their feed better resulting in more nutrition being absorbed to make more and better eggs.
2. In broilers, the grit helps digest the whole grains added to their mash during the finishing period. This results in significant weight gain in the finished birds.
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Grit that is too small for the bird's age and needs simply passes on thru the G.I. tract and does not benefit the bird. This is why sand is not a good idea for chicks. They need "flint grit" , i.e., chick-sized grit with sharp edges which do not wear down easily.
Oyster shell is good for providing calcium to the hens for laying. However, it does not do well for supplying grit for digestion because the sharp edges are easily worn away by the acid in the gizzard. This is why we feed both insoluble grit and oyster shell to laying hens.
None of the calcium supplying substances we could call and use as "grit" are best for both supplying grit and calcium. Supplying high magnesium* limestone grit for chicks is actually very harmful. It is much better to use insoluble grit plus either oyster shell or cockle shell for calcium. Tho research proves oyster shell is the better choice.
* low magnesium limestone grit can be used to advantage in certain poultry areas. However, the combination of insoluble grit and oyster shell has been proven scientifically superior so why stress using the limestone grit?.
Best,
Karen
Here is the source for much of my research. This pithy little book not only has the biblio cites, it has abstracts of each one. A wealth of knowledge on many aspects of grit. Tied in well with the other scientific articles I was reading on the Net.
Grit for poultry: bibliography and abstract.
Author: Branion, Hugh Douglas, 1906-
Published: New York, Granite Grit Institute of America [1960]
Physical Description:
84 p. 28 cm.
http://babel.hathitrust.org/cgi/pt?id=wu.89043737196;view=1up;seq=1

I know the answer is somewhere here on this site but I sure can't find it. Should you mix the Grit with their feed or feed it separately? Right know I have it setting in a pan next to the Oyster shells. The shells seem to be going fast but it doesn't seem that they are eating the grit. They do free range but the ground is frozen, so I am think that it is grit time. Thank you for any information. Oh! the hens are nine months old and they are all laying.

Liberty For All said:

I know the answer is somewhere here on this site but I sure can't find it. Should you mix the Grit with their feed or feed it separately? Right know I have it setting in a pan next to the Oyster shells. The shells seem to be going fast but it doesn't seem that they are eating the grit. They do free range but the ground is frozen, so I am think that it is grit time. Thank you for any information. Oh! the hens are nine months old and they are all laying.

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you should mix it with their feed.

Liberty For All said:

I know the answer is somewhere here on this site but I sure can't find it. Should you mix the Grit with their feed or feed it separately? Right know I have it setting in a pan next to the Oyster shells. The shells seem to be going fast but it doesn't seem that they are eating the grit. They do free range but the ground is frozen, so I am think that it is grit time. Thank you for any information. Oh! the hens are nine months old and they are all laying.

Click to expand...

Hi,
They will pick up the grit as they need it. If you are feeding the correct size it can stay in their croups for a while unlike too small a size which will just pass on thru them. You are right to be feeding it in separate dishes. can top their feed with the granite if you think they need a nudge to start using it. Check back with the gran-I-Grit PDF above. Feeding info ( including which size to feed at what age) is on the 2nd page of that PDF .
Best,
Karen

I don't want to play devil's advocate but the studies I read on grit had a focus on consumption of feed. Obviously feed consumption is key concern of large poultry operations. Granite is the best stone for grinding. No question about it. Will the difference of stone poultry pick from the ground opposed to perfectly sized granite bits be notable to me a back yard poultry man with max of 100 growing birds in spring and 18 going into winter? No. Not really, it's small with those few numbers of birds. The choice of range forage or not is a much larger impact of feed. Those that keep a run only should provide grit but crushed stone is better than smooth and free apposed to crushed granite. It is very noticeable through winter if grit is not supplied and you live in a frozen waste land. I grab a small pail from driveway each fall for this reason. Mixed source of crushed stone, so surface fractured which is a big difference to smooth in grinding.

I completely agree grit is important. I also agree that crushed is better than smooth. But I'm completely fine with allowing free range and free grit source finding all spring to fall and simply wouldn't ever purchase stone. It's only stone.

Hi Eggead,
I thought so too until I read the 80 page bibliography referenced above. Study after study proved that consistently using a sharp edged insoluble grit would make a difference in the size of the gizzard. This can make up to a 20% increase in the number of eggs the hen lays when mature. Honest, I didn't make this up, It's there in the bibliography and other scientific papers I read on the Net. The concern with field stone is not the contrast in the type of stone itself ( field vs. granite) . It is in the consistency of the difference in the stones. Consistent feeding of a consistent type of grit.
Best,
Karen

Thank you. The grit is a good size. Bigger than I expected. But bought from a reputable source. Thank you again.