Minerals are generally listed in two ways on a feed tag guaranteed analysis.
- Macro minerals, or those needed in larger quantities, are expressed as a percentage. They include calcium, phosphorus, sodium, chlorine, potassium, magnesium, and sulfur.
- Micro minerals, or those needed in smaller amounts, are expressed as “parts per million” which is what the “ppm” on the tag stands for. Occasionally a feed tag will list these in “mg/kg”, which converts directly to ppm – 1 ppm is equal to 1 mg/kg. These minerals include selenium, iodine, copper, zinc, manganese, and iron.
When analyzing a feeding program, it is of great importance to make sure that the same units of measurement are being used. Often times, test results for a hay sample that has been analyzed will not be expressed in the same unit of measure as the nutrients guaranteed on a bag of feed. So, in order to know what the entire diet is providing, make sure you are comparing apples to apples!