Oyster shells VS. clamshells

[Percheron chick]

Here's info on the different kinds of calcium: I don't know how chickens would absorb them. If there is a difference. 8 Common Types of Calcium 1. Calcium Carbonate A common form of calcium supplement, calcium carbonate is an alkaline-based compound found in rocks, limestone, shells of marine animals, pearls, eggshells and snails. It holds one of the highest concentrations of elemental calcium (35-40%), but is not high in bioavailability and requires the production of extra stomach acid to be absorbed. Bioavailability refers to the amount of calcium in the supplement that can be assimilated by the digestive system, and ultimately used for cellular activity and health benefits. Calcium Carbonate is currently one of the cheapest and most prevalent forms of calcium supplements sold today. Be sure to avoid this form and check all of your multivitamin / mineral supplement labels. 2. Calcium Citrate Differing from the alkaline qualities of calcium carbonate, calcium citrate has an acidic base. This acidity requires less production of natural stomach acids, allowing this type of calcium to be better absorbed than the carbonate form. It does, however, have less elemental calcium concentration (20%), and again, low bioavailability. 3. Oyster Shell Calcium While it may seem like a more natural form of calcium, and thus higher in absorbable content, oyster shell calcium, as well as dolomite and bone meal, are difficult to quality-control and have been found to show levels of lead toxins. In general, these “natural forms” of calcium should be avoided. 4. Calcium Gluconate A form of of calcium with very low levels of actual calcium concentration. You would need to take very large amounts of the supplement to reach calcium requirements, and the bioavailability is still not certain. 5. Calcium Lactate The form of calcium found in foods such as aged cheese and baking powder. This form is the most commonly used antacid and is added to fruits to keep them firm and extend shelflife. It has a medium bioavailablity in the body because it can be absorbed at various pHs. 6. Calcium Phosphate The main form of calcium coming from cow’s milk. Tooth enamel and bones are very high in calcium phosphate, although supplemental forms have not shown to be readily bioavailable. 7. Calcium Citrate Malate A water-soluble form of calcium. It is created through mixing the calcium salt found in citric acid with malic acid. This combination has higher levels of bioavailability than other forms, as it is water-soluble and does show some evidence of being dissolved into cell membranes. More bioavailable than the other forms listed above. 8. Calcium Orotate The most effective form of calcium supplement, created through the use of the mineral salts of orotic acid. Calcium orotates are found in small amounts in all living beings. It is a primary mineral for the creation of bones and teeth, and fosters cellular communications. Both plants and animals use orotates to create DNA and RNA. Extensive scientific research done by by Hans A. Nieper, M.D. has found that orotates can penetrate cell membranes, enabling the effective delivery of the calcium ion to the inner-most layers of the cellular mitochondria and nucleus.

This is a little misleading because it's in reference to human nutrition. Bottom line is egg shells, oyster shells and clam shells are all approximately 95% calcium carbonate. Chickens can readily absorb Ca in this form. Oyster shells are pulverized to the point that they look more like a powders. For the clam shells to be of value, you're going to have to crush them into small enough particles for them to be absorbed or they'll be more like grit and pass through them.

 

[fingbob]

I presume your "clams" in Oregon are the invasive Corbicula sp. Look up on internet to confirm. If yes, then value of shells as Calcium source will be comparable to oyster shell.

I am in Veeerrryyy northwest Oregon, and we have the razor clam. the shell is thin and can cut a person if not care full while trying to dig the fast digging buggers out to the sand. There are also bay clams but they are about a hour and a half drive. We dig the razor clam quite often and thought it would be a nice alternative to buying oyster shells.

 

[Mountain Man 60]

I have wondered this also. I was using clams from the VA shore/supermarket after making clams linguini as they were available. Why pay someone for a bag of what you have available for free? I picked up a bucket of oyster shells from the beaches of the outer banks while on vacation and there appears to be a big difference between clam and oyster shells when you process them. Using a hammer and stone if you hit an oyster shell it crumbles into looser shards and powder while the clams break into small pieces but do not crumble as much as oyster shell. This leads me to believe that oyster shell would more likely dissolve further in acid than clam shell. When using clam shell I did see the shell coming out in the chicken manure. They would pick at it and recycle again until dissolved so it probably acts more like a rock in the gizzard than oyster shell. I just fed the first batch of oyster shell today but by the feel of it I am assuming it will be fully absorbed. I will continue to use both as they are available from my travels or seafood purchases. I have also given them shrimp shells. They pick off the legs first but eventually eat the body shell once it dries out and can be broken.

 

[FinnIslander]

For those of you who've used (or are using) clam shells, I'm wondering if I use one of the types of sand that I have readily (and freely) available in my coop will the hens get any benefit from having the bits of clams shells mixed in... or would I still have to supplement their feed. Thanks!