Hi, Melissa!  In addition to Lavinia's excellent response, here are some interesting numbers for you:

The Omneity IR mix has a bunch of stuff of questionable value, but bless their hearts for including the iron figures!  This allows us to coax out how much of the copper and zinc are "useable" (ie,not negated by the iron)

Each serving gives81 mg of iron (actually, a nice, low number); plus 275 mg zinc (214 mg useable); and 45.6 mg copper (20 mg useable)  It costs $2.00 per day.

Now, have a look at the Trace Mineral Mix:  negligible iron, as what is in there is just from the manufacturing process, not from the dicalcium phosphate or other ingredients.   523 mg zinc, 130.7 mg copper, 5.44 mg I, 3 mg selenium.  (similar iodine and selenium in the more expensive Omneity mix)  The cost is $0.20 per day.  Twenty cents per day vs two dollars per day.

To be sure, the Trace Mineral Mix won't supply calcium, magnesium or phosphorus, but the Trace Mineral Mix is only a stop gap while you are getting the new hay analysis.  At that time, we can address the major minerals.

Mad Barn means well, but they are lacking some crucial and cutting edge information on equine mineral absorption and IR/PPID.

No worries about asking questions - it IS a steep learning curve, and no one is born knowing about IR, PPID, horse nutrition or the sometimes dubious marketing practices of feed companies.

I am quoting Lavinia below, as this sentence nicely states what so many of us have learned, sometimes after prolonged, expensive, and detrimental efforts to the contrary:

" The best product is going to be the one that most closely matches and complements the excesses and deficiencies in your particular diet. The kitchen sink approach is never the best or most economical."

Cheers,