Everything Horses and Livestock® Magazine May 2018 Vol 3 Issue 2

Everything Horses and Livestock Magazine ®

percentage of the product. However, the actual intake of trace minerals is less obvious and requires different methods of calculation. Let’s look at how to

10 PPM Cu, which is a good upper limit for most grass hay products. Along with this let’s use an extreme level like Total Sheep Mineral that contains 1,000 PPM Cu. At first glance this is very extreme and would be very toxic. In reality, this is a safe level when the consumption of both hay and mineral are considered as follows: 4.5 LB hay per day = 2.043 KG = 20.043 MG Cu/day 0.35 OZ Mineral/day = .0099 KG = 9.931 MG Cu/day Total Cu intake per day = 29.974 MG Cu/ day = 14.67 PPM So, when reading a feed tag use this method to understand the total PPM of trace minerals and then consider the bioavailability of the sources

PARTS PER MILLION (PPM) Parts per million (PPM) are units that appear on every feed tag guaranteed analysis and are poorly understood. First of all, PPM is not a unit of measure that can be directly applied to how much of whatever nutrient expressed in this way. Legally this is the unit that must be used for all trace minerals and several other small inclusion items in a feed. A much better unit of measure would be milligrams per lb. and I will explain why as we go through this. Let’s look at how the units of measure relate to each other. The following is how the comparisons can be calculated to understand what an animal actually consumes based on PPM.

derive at this number. To show this I will use a recent controversial item and that is Copper (Cu)intake by sheep and how this created a concern by many people when they looked at the level of copper in Total Sheep Mineral. The accepted toxic level of Cu in a sheep diet is 25 PPM as an upper safe limit, so to calculate the safe MG copper per day for a mature female sheep it would be calculated as follows with an

estimated dry feed intake of 4.5 lb./day: 4.5 LB = 2.043 KG 25 PPM for 2.042 KG intake = 51.075 MG copper per day So, if 51.075 MG Cu per day is the upper safe level, how do you calculate the safe intake order to do this, the Cu level in all feed the sheep consumes must be considered. Assume this sheep is consuming a forage product that contains of any given product? In

1.0 1.0 1.0 1.0

Kilogram (KG) = 2.20264 Pounds (LB)

KG = 1,000 Grams (GM) GM = 1,000 Milligrams (MG) LB = 16 Ounces (OZ)

1.0 OZ = 28.375 GM PPM = MG/KG

When we read a feed tag, what we want to know is the actual units of any nutrient that the animal derives from that product as that is the important number to know. Calculating the intake of a nutrient such as protein or calcium is simple since they are expressed as a

Everything Horses and Livestock® | May 2018 | EHALmagazine.com 6