I did some research on caring for horses with trace mineral deficiencies and how to check the mineral contents on the feed bag label. What's tricky is that deficient horses often show no clinical signs until they are severely deficient, but a chronic deficiency inhibits performance and jeopardizes health, and that feed bag labels often use different units of measure to express the amount of trace minerals in the grain pellets. To understand trace mineral contents one should also understand the term "ash", since I came across several documents using this term, and parts per million (ppm), commonly used as a measure of small levels (concentrations). Let's start with ash.
What is Ash?
Ash is simply the total mineral content (TMC) of a forage, or diet. Ash content of forage or grain rations is easy to measure in a testing laboratory. In general, ash content, or TMC, is determined by a process similar to cremation and with an emission spectrometer. The forage is burned at 500°C for 2 hours and the residual minerals, often called inorganic material, are determined. The laboratory procedure is extremely accurate and precise, but it is important to understand that the procedure measures the simple sum of all minerals in the feed.
Minerals in feeds can be broken down into two general categories, endogenous and exogenous. Endogenous minerals can be loosely defined as minerals plants normally contain such as calcium, phosphorus, potassium and magnesium etc.
Here is a website where you can ****Click on YOUR state**** to access documentation regarding its pasture and soil trace mineral status.
What is PPM?
CALCULATING WITH PPM IN TWO EASY STEPS
Some trace mineral contents in feeds and supplements is provided in terms of parts per million (ppm) on the ingredients list. PPM is the same as mg per kg, expressed as mg/kg, where 1 mg is a millionth of a kg.
Knowing this, the first step is to do calculations. You first need to convert pounds (lbs) or ounces (oz) to kilograms (kg) using the following conversion formula:
· 1 lbs. equals 0.454 kg
· 1 oz equals 0.0284 kg
Formulas to remember:
Convert lbs. or oz to kg: __lbs x 0.454 = __kg
__oz x 0.0284 = __kg
Calculate to find mg: kg x ppm (or mg/kg) = __mg
Example #1: Your hay contains 140 ppm of iron. How much iron is in 20 lbs. of hay?
Step 1: Convert pounds to kilograms, 20 lbs. x 0.454 kg = 9.08 kg
Step 2: 9.08 kg x 140 mg/kg = 1271 mg of iron
Example #2: Your supplement contains 12 ppm of selenium in each ounce. You are feeding 2 ounces per day. How much selenium are you feeding?
Step 1: 2 oz x 0.0284 kg/oz = 0.057 kg
Step 2: 0.057 kg x 12 mg/kg = 0.68 mg of selenium