Every week Dr David Marlin looks at a different common equine supplement ingredient and explains what it is, what it is made from, what effects people hope it will have, and any benefits or drawbacks to using it as a feedstuff for horses. There are literally hundreds of different ingredients used in equine supplements. Here is a shortexplanation about the most common ones and evidence for efficacy, if any exists. Copper Chelate Inorganic forms of copper, such as copper sulphate, can be irritant to the stomach. Organic sources of copper, such as chelated copper, are kinder on the digestive system…