I have mentioned briefly in other blog posts about chelated (organic) minerals but would like to explain further the differences and benefits when compared to inorganic minerals (non-chelated).
Inorganic minerals are lower-cost, easy supplementation minerals that have historically been used. However, with more research, it has been discovered that these "unprotected minerals" have very low availability to the animal and are often wasted. The theory of feeding more so they will get something does not apply to inorganic minerals, this just creates more waste in the excreted feces. This happens because these minerals are bound to sulfate or oxide which do not contain carbon. This is why they are cheaper to produce, however without the carbon, these molecules can be bound to other things which will increase the size of the molecule, and absorption in the small intestine of these larger molecules is limited. Therefore, these molecules can not reach the bloodstream as rapidly and the bloodstream is the only way these minerals can be fully utilized.
Each metal; for example copper, cobalt, or magnesium; has a certain number of available spots to bond with other molecules. As you can see from this image, the chelated mineral is bonded at two places and the inorganic is bonded at only 1. This leaves a spot available to bond with other molecules while passing through the rumen. This is why sulfates, molybdenum, and iron can cause a deficiency in other minerals such as copper. They will tie up the copper and make it unavailable for absorption from the small intestine.
Chelated minerals are bound to amino acids, which pass through the rumen to be readily absorbed in the small intestine. These are then passed directly into the bloodstream and move around the body to the locations they are needed. Minerals such as copper, zinc, and manganese are susceptible to dietary antagonists such as molybdenum, iron, and sulfates. When these minerals are in the inorganic form, they will bind to these antagonists and be rendered unavailable to absorption the small intestine. These minerals are then excreted from the animal and are not utilized. Chelated minerals have been shown to increase pregnancy rates, especially catttle expierencing nutriitional stress before breeding. These minerals can help to sync cattle cycles for artificial insemination. Chelated minerals have also been proven to boost immune response and "prime" the immune system prior to high stress times due to mineral accumulation in the liver stores.
So in summary (for anyone who doesn't want to read the science jiberish):
Chelated minerals cannot bind to other molecules, therefore stay small enough that they can be absorbed in the small intestine.
Chelated minerals are more readily absorbed.
More is not always better! Providing lots of inorganic minerals does not increase the ability to absorb, so you might as well just put your money on the ground and save the cow some energy.
Chelated minerals can help to "prime" the immune system prior to times of stress.
Liver stores can be filled more rapidly with chelated minerals compared to inorgainic minerals. This store of minerals allows their requirments to be met even in high stress environments.