Multimin: What the Research Actually Says About Conception, Calving, and Calf Growth

Producers ask me about Multimin all the time — usually because someone in their region told them it would lift their conception rates 10 percent. The published research is more nuanced than that. Multimin can move conception, calf health, and vaccine response under specific conditions. In other conditions it does nothing measurable. The difference is whether the herd is already mineral-adequate. Here is the working summary of what the literature says.

What Multimin is

Multimin 90 is an injectable trace mineral product. Each mL contains 60 mg zinc, 10 mg manganese, 5 mg selenium, and 15 mg copper. The label dose is 1 mL per 100 lb of body weight given under the skin in the neck — so a 1,300-lb cow gets about 6 mL. The mechanism is straightforward: the injection routes around the rumen, where most oral trace minerals get tied up by antagonists like sulfur and iron in the forage, and loads the liver directly with bioavailable mineral within days.

Effect on conception in cows

The strongest pre-breeding conception data comes from a Kansas State trial by Mundell and colleagues. Mature beef cows on native range received Multimin 105 days pre-calving and again 30 days pre-AI. Fixed-time AI pregnancy ran 60 percent in treated cows versus 51 percent in controls — a 9-percentage-point lift.¹ After cleanup bulls finished the season, the final pregnancy rate was the same in both groups. The takeaway: Multimin can shift FTAI conception, but it does not change whether cows eventually get bred.

The catch is that the response depends on baseline mineral status. A University of Nebraska–Lincoln trial in heifers with adequate liver copper, manganese, selenium, and zinc found no reproductive benefit at all.² A separate trial reported decreased AI pregnancy rates after repeated injections in cows that did not need them.³ This is not a free lunch on mineral-adequate herds — and at standard product pricing, it is not cheap either.

Effect on conception in ET recipients

The single dedicated ET recipient trial was run on crossbred Brahman-influenced heifers in Brazil. A single injection of copper, selenium, zinc, and manganese given 17 days before timed embryo transfer significantly improved pregnancy rate per ET — roughly a 10-percentage-point lift in conditions where the heifers were on tropical pasture with marginal mineral status.⁴ The biology is consistent with the FTAI work: when baseline mineral status is marginal, the injection moves the needle.

For a Florida or Southeast recipient program on summer pasture with iron-heavy soil and sulfur from groundwater, this is a defensible intervention. For a program on a well-managed mineral mix where liver biopsies would come back adequate, it is harder to justify.

Effect on calving and the newborn calf

Pre-calving Multimin clearly raises calf liver copper and selenium at birth — that part is well documented.⁵ Where the literature gets thin is on whether that loaded mineral status translates into measurable differences in colostrum, calf vigor, scours rates, or weaning weights. The strongest controlled beef trial during gestation showed no difference in calf morbidity or mortality, lower birth weights in treated calves, and no difference in pre-weaning gain.⁶ The pre-calving claim is the weakest leg of the Multimin evidence base in beef cattle.

If a producer wants to move calf-side health metrics, the evidence is stronger for injecting the calf at branding or weaning than for injecting the dam in late gestation.

Effect on vaccine response in calves

This is the strongest and cleanest evidence in the Multimin literature. Arthington and Havenga gave weaned beef calves either Multimin or saline at the time of a modified-live BHV-1 and BVD vaccine. The Multimin-treated calves had significantly higher virus-neutralizing antibody titers at 14, 30, and 60 days after vaccination.⁷

What it does not consistently do is move average daily gain or weaning weights when the calves were not mineral-deficient to start with. The vaccine titer effect is real and reproducible. The growth-and-pounds effect is conditional on baseline status, just like the cow-side conception data.

When I think it makes sense

Where the published evidence supports use: pre-breeding in herds running on Southeast summer pasture where forage analyses or liver biopsies show marginal copper, zinc, or selenium status; in Brahman or Brahman-influenced ET recipients pre-transfer; and at the calf level around vaccine time. Where the evidence is weakest: dosing already mineral-adequate herds, or expecting pre-calving injection to fix calf-side outcomes that are really colostrum and management issues.

When it is a bad idea

Stacking Multimin on top of a well-formulated free-choice mineral and a high-copper bolus is a known cause of copper toxicity, particularly in continental or dairy-influenced breeds that store copper aggressively. Kansas State's veterinary diagnostic lab has flagged this directly in cases of unexplained cattle deaths.⁸ If a herd is already on an aggressive mineral program, talk to a vet before adding an injectable on top.