If you have to give 3 grams (elemental mineral amount) and your product (MgO) is 58% pure, the 3/0.58 = 5 grams (weight) of product (MgO). Totally up to you if you split it or give it all at once. A lot of that will depend on whether your horses eat it readily. BTW, when dosing minerals, it's always wise to start slow. Start with a half dose and see if they eat it. If NO, then decrease by another half, even if you have to start with just a pinch. Once they accept it, start working your way up to the full dose. You'll find this helpful when you start giving the full compliment of minerals based on your hay analysis.

Kathleen (KFG in KCMO)

Missouri, USA Dec 2005