There are ten trace mineral elements that are considered in balancing dairy rations:
− Cobalt (Co)
− Copper (Cu)
− Iron (Fe)
− Iodine (I)
− Manganese (Mn)
− Selenium (Se)
− Zinc (Zn)
− Molybdenum (Mo)
− Chromium (Cr)
− Fluorine (F)
The trace mineral element concentrations in common forages and concentrate feeds are quite low and can vary considerably, even among different sources of feeds with the same name. Therefore, when using NDS it is recommended that all trace mineral elements are supplemented in the ration at 100% of NRC DAIRY (2001) requirements.
In NDS Feed Library the concentrations for the trace mineral elements are set for all common feeds as total elements. However, trace mineral concentrations can be listed for specific inorganic mineral sources as total elements and added elements in order to provide an overview of the total supply vs. the supply from added sources (different from forage or main raw materials).
Bioavailability (efficiency of absorption)
Like for macro minerals, not all of the various trace mineral elements in rations are available for absorption. Therefore, NDS adopted the NRC (2001) approach of using an absorption coefficient to supply adequate mineral elements in rations.