Above on the left is the relevant portion of the output provided you by Equi-Analytical for their (601) Equi-Tech hay analysis. For purposes of education I also added a test for Selenium (not part of the Equi-Tech analysis). I already know I live, and my hay comes from, a selenium deficient area of the United States (and Canada where this hay came from). On the right side is a portion of the spreadsheet I have for analyzing the diet in total,including all feeds and supplements. I’ve selected just the hay portion for the purposes of this post. It shows what 20lbs of hay/day provides the horse. 20lbs/9kg per day is what you would feed a 1000lb/454kg horse if feeding at 2% of desired body weight. As you can note from the analysis on the right, this hay provides way too much Iron (Fe) and Manganese(Mn) at a gram each and not near enough Copper (Cu) or Zinc (Zn) to combat excessive uptake of those two potentially toxic minerals. How do I know there is too much Fe and Mn and not enough Cu or Zn? I’ve used the National Research Council Nutrient Requirements of Horses, 6th Edition to create my spreadsheet with modifications suggested by…