I have been curious about the same thing. Should I be using Multimin? I decided to check this out.

From their website, Multimin 90:

"Multimin^® 90 (zinc, copper, manganese, and selenium injection) is the only FDA-approved injectable supplement that delivers four trace minerals precisely..."

All four of these are also contained in Mineral-lyx mineral tubs, plus quite a few more according to the Mineral-lyx product data sheet.

From my experience Mineral-lyx, in barrels and in a molasses base, is definitely consumed better than the dry minerals I've tried.. I keep it out all year around. All cows, calves, steers and bulls use the barrels. With new born calves they get these and other minerals from mama before and after calving.

The Multimin manufacturer does make a point about inconsistent consumption of [dry?] minerals, which is NOT a problem with Mineral-lyx. My conclusion is that with my year-round Mineral-lyx program a multimin shot is not necessary. 

I would agree with the multimin manufacturer that not all minerals are consistently consumed which we seem to discuss here regularly.

A few years ago, before I moved calving  back to about May 1 here in Wisconsin, I had a newborn calf die. Vet suggested we have him posted by the UW Vet Clinic. When the report came back there was no problem found. Calf died of hypothermia after being born during a blizzard. The UW clinic did comment on how the calf seemed to have very high mineral counts for everything they checked. This was no doubt due to the use of Mineral-lyx.