Mineral for Cattle in Winter: What Cows on Hay Really Need

By the XES Netting team — bale net-wrap manufacturer · Updated October 7, 2026 · ~16 min read

Mineral for cattle in winter is one of the smallest lines in a cow budget and one of the most argued about. On AgTalk the debate runs from whether plain salt is enough, to whether a $32 bag beats a $25 bag, to why the cows emptied the feeder one week and ignored it the next. Underneath the arguments is a simple fact: a cow wintering on hay eats stored forage that is often short of trace minerals and vitamin A at the exact time she is building her calf’s reserves.

This guide is for cow-calf producers wintering beef cows on hay, baleage, cornstalks or stockpiled grass. It is not a ration or veterinary recommendation; work with your veterinarian, a nutritionist or your county Extension office, especially on selenium. XES manufactures bale net wrap, not mineral, and has no mineral brand to sell. We read 33 archived AgTalk and HayTalk discussions about cattle mineral (369 posts, 29 of the threads from 2022–2026) and checked them against University of Nebraska–Lincoln and University of Georgia Extension guides, the federal selenium rule, a trace-mineral salt label and a peer-reviewed analysis of salt.

Why cows on hay still need mineral

Outright mineral deficiency is uncommon in beef herds. The problem is the quiet kind. Mary Drewnoski’s University of Nebraska–Lincoln guide, Formulation Considerations for Mineral and Vitamin Supplements for Beef Cattle (G2340), says subclinical deficiencies that reduce calf growth, calf health or reproduction “are much more likely,” and names copper and zinc as the most common trace-mineral shortfalls in beef cow systems.

Winter timing makes them matter more. The same guide explains that in late gestation the cow stocks her calf’s liver with copper and zinc, because milk is a poor source of trace minerals and the newborn depends on those reserves until it eats solid feed. For spring-calving herds, late gestation happens on hay.

Hay itself is part of the story. The University of Georgia’s Mineral Supplements for Beef Cattle (B895) notes that cattle are more likely to be phosphorus-deficient in winter, when they subsist on dry forages, and that vitamin A deteriorates in storage. What a cow is short of depends on what she is eating:

Nebraska’s numbers show how common the gaps are: of grass hay and pasture samples Nebraska producers sent to a commercial lab, 80% held less than the 30 ppm of zinc cows require. If you have not tested your hay for minerals, our guide to reading a hay test covers how to take a sample that represents the stack, and our rained-on hay guide explains what weather washes out.

Salt is not a mineral program

The longest mineral thread in the archive started in November 2025, when a Missouri producer with too many open cows asked whether sea salt and baking soda could replace mineral, after hearing on a podcast that salt holds most or all of the minerals a cow needs. Most replies pushed back.

"We fed just salt for years, started mineral this summer, and am going to keep feeding it. Open rate with mineral seemed to be lower"

— Kylidge McNally, Bethune, SK · AgTalk thread 1220737

That is one farm’s experience, but the arithmetic backs it. Unrefined salts do carry trace minerals — in parts per million. The most detailed published analysis we found, Fayet-Moore and colleagues in the journal Foods (2020), tested 31 pink salts bought from Australian retailers and found 0.01 to 0.41 mg of copper and 0 to 0.86 mg of zinc per kilogram. Georgia’s B895 says cattle eat about 0.005% to 0.010% of their body weight in salt a day, or roughly 1 to 2 ounces for a 1,300-lb cow. Nebraska’s G2340 builds its tables on that same 1,300-lb cow eating 2.5% of body weight, which works out to about 147 mg of copper and 442 mg of zinc a day at the 10 ppm and 30 ppm requirements.

XES calculation from Fayet-Moore et al. (2020), the Champion’s Choice Selenium ‘90’ product sheet and UNL G2340. Forage supplies some copper and zinc too, which is why Nebraska’s zinc guideline covers only part of the requirement; the point of the table is scale.

Plain salt supplies about two-hundredths of 1% of a cow’s copper. A trace-mineral salt is a real step up but still leaves most of the copper gap, which is why a tag listing copper in the hundreds of ppm is not the same thing as a complete mineral at 1,300 ppm or more.

Baking soda does not change that math. It supplies sodium and no trace minerals, and Ohio State University animal scientist Francis Fluharty describes bicarbonate as a weak buffer, noting that a forage diet runs a rumen pH around 6.8 compared with about 5.3 on a high-grain diet. Some producers in the same thread offer bicarbonate when they turn cows onto cornstalks to head off digestive upsets; on stalks the usual culprit is spilled grain, which our cornstalk grazing guide covers.

How much mineral a cow should eat

Free-choice minerals are formulated around a target intake, usually 2 or 4 ounces per head per day; the tag says which. Nebraska’s G2340 makes the key point plainly: “Cattle do not vary their mineral intake based on their mineral needs.” Salt drives intake. A 4-ounce mineral typically needs 15% to 25% salt and a 2-ounce mineral 30% to 40%; more salt in the mix means cows reach their salt “fix” with less mineral.

"This summer actually tracked usage to see how close we were to the "4 oz/hd/day" recommended consumption and although it varied from time to time, the average over the summer ended up pretty much right on that amount used per head. At current costs, that calculates out to 18 cents/head/day."

— lhfarms, NE Iowa · AgTalk thread 1097615

Others never hit the target. A west central Illinois producer wrote that “every mineral always says they’ll consume 4 oz per day and I never go through that much,” and water source can swing it further:

"When they drink city water mineral consumption quadruples. every winter mineral consumption drops to almost nothing."

— Jdel, Wheelersburg and Lancaster, Ohio · AgTalk thread 1220775

The only way to know is to measure. Weigh what you put out and what is left over a week or two, then:

Ounces per head per day = pounds of mineral eaten × 16 ÷ head ÷ days. Example: 100 lb eaten by 50 cows in 8 days = 100 × 16 ÷ 50 ÷ 8 = 4.0 oz. Count calves that can reach the feeder.

Then adjust the way Nebraska’s guide recommends:

1. Too much intake: mix extra salt into the mineral, or move the feeder farther from water and loafing areas. The guide recommends mixing salt into the mineral rather than offering a separate salt source, which can leave cows eating only salt.
2. Too little intake: move feeders closer to water or loafing areas. Molasses or distillers grains can improve palatability, especially for bitter high-magnesium mixes.
3. Enough feeders: about one feeder per 30 cows so timid cows get access.
4. After a run-out: put out straight salt for a day or two, then refill the mineral and remove the salt, so cows do not gorge on the fresh mineral.

Some producers deliberately offer plain salt in a second compartment to rein in mineral intake. If you do, measure both; the risk Nebraska’s guide describes is cows satisfying their salt craving and skipping the mineral.

What winter mineral costs per cow

The useful number is cost per cow per year, not price per bag. At 2025 forum prices of roughly $20 to $35 per 50-lb bag, here is what common intakes cost over a full year:

XES calculation. Each extra ounce a day is about 22.8 lb a year, or roughly $9 to $16 per cow at these bag prices.

The reported figures fall inside that table. In a January 2023 cost thread, producers in southern Indiana and Arkansas were at 10 to 11 cents a head per day, a North Dakota herd worked out to about $40 a cow a year, and the northeast Iowa herd that measured a true 4 ounces was at 18 cents a day, about $66 a year. In 2025, a northwest Wisconsin producer listed direct-shipped prices from about $21.50 a bag up to $35 with fly control and an organic trace-mineral additive, and another producer buys from a small local mill at $28 a bag.

The bag price can mislead. A west central Illinois producer who switched from a $25 basic mineral to a $32 breeder mineral reported going from a little over a 50-lb bag per cow per year to 35 to 40 lb, adding: “So using the better mineral actually costs me a little less.” That herd also has salt in a second feeder compartment, which the same post flags as a possible factor. Nebraska’s G2340 makes the broader point in italics: “A good mineral program does not have to be expensive, nor is cost correlated with effectiveness.” Supplementing a mineral the cow is not short of buys nothing; the guide says a benefit appears only when a deficiency is being corrected.

Reading the tag for a hay diet

Nebraska’s G2340 gives tag concentrations for a free-choice mineral eaten at 4 ounces a day by a 1,300-lb cow. Double them for a 2-ounce mineral.

Three tag details separate good minerals from cheap-looking ones:

• The form of copper. G2340 rates copper sulfate as fully available and copper oxide at only 15%, so oxide needs almost seven times more copper to deliver the same amount. Georgia’s B895 recommends sulfate, tribasic copper chloride or an organic form.
• Vitamin A per day, not per pound. Divide the IU per pound by four to get the daily dose at 4 ounces. A tag reading 100,000 IU/lb supplies 25,000 IU a day, well short of the 42,000 IU Nebraska suggests for a dry cow on stored feed. The guide adds that the most common sign of vitamin A deficiency in a cowherd is more illness and diarrhea in young calves; our old hay guide explains why beta-carotene in stored hay declines.
• What should not be there. G2340 advises against added iron in beef cattle minerals (multi-species mixes often include it, and it interferes with copper, zinc and manganese absorption); iron oxide used for color is unavailable to the animal and interferes less. B895 flags added B vitamins as an unnecessary cost for cattle whose rumen makes them.

"Mineral is a local deal, varies with what naturally occurs in your soil and feed."

— WCWI · AgTalk thread 1220737

Selenium: know your region, then do the math

Selenium is the one mineral where too much is as serious as too little. Georgia’s B895 links deficiency to white muscle disease and weak calves, more retained placentas and poor reproduction in deficient areas; Nebraska’s G2340 warns that “the margin of difference between Se adequacy and Se toxicity is exceptionally narrow” and that toxicity has occurred when injectable minerals and several fortified supplements were used at once.

Federal law sets the ceiling. Under 21 CFR 573.920, a salt-mineral mixture for free-choice feeding to beef cattle may contain up to 120 ppm selenium, at a rate not to exceed 3 mg per head per day. One forum reply put the free-choice limit at 165 ppm; the rule says 120 ppm and 3 mg a day. The daily dose is easy to check:

Milligrams of selenium per day = ppm on the tag × ounces eaten × 0.02835. A 4-oz mineral at 26 ppm supplies about 2.95 mg, which is why Georgia’s guide says a 4-oz label cannot exceed 26 ppm.

Several producers in low-selenium areas mix a selenium trace-mineral salt into their regular mineral. Check the label first: the Champion’s Choice Selenium ‘90’ sheet says to feed it “as their only source of supplemental Selenium” and to limit feed if consumption exceeds 1.16 ounces a day, the amount that supplies 3 mg. Blending one part of a 90 ppm salt with two parts of a 26 ppm mineral makes a mix of about 47 ppm; at 4 ounces a day that is roughly 5.4 mg, nearly double the cap. Pick one fortified source, keep the total at or under 3 mg, and ask your veterinarian about whole-blood or liver testing if you think your herd is short.

Are chelated minerals worth it?

“Chelated minerals worth the expense and hype?” was a 21-post AgTalk thread in early 2025, and the answers split the way the research does.

"Availa 4 was a game changer here. I will add our soils are low in Cu."

— Simocattle, Central SD · AgTalk thread 1188968

"I used it for awhile, was nice it didn't get hard, but reproduction was not as good as what I am feeding now, but that all depends on what you need to match up to your soil and feed makeup."

— WCWI · AgTalk thread 1188968

Nebraska’s G2340 lands in between. Inorganic sources are generally the most cost-effective way to supply minerals, and the guide concludes: “In most cases, a properly designed mineral with inorganic sources can meet the needs of the herd.” Organic forms such as copper lysine or proteinate may help when a herd’s status has to change quickly; in those cases the guide suggests supplying about half of that mineral from an organic source, or using an injectable trace mineral before breeding or calving. Copper chloride, an inorganic form, was about 20% more available when molybdenum and sulfur were high. The practical order is: get the concentrations and forms right first (sulfate or chloride, not oxide), then pay for organic forms where a documented deficiency or heavy antagonists justify it.

Loose mineral, blocks or tubs

Loose mineral in a covered or weatherized feeder is the easiest format to measure and adjust. Georgia’s B895 says blocks can work when grass tetany is not a risk, provided trace minerals are raised to make up for the lower intake of a hard block, but recommends loose salt and minerals when tetany is a risk. Tubs are a different product category; as one Wisconsin producer put it, “Protein lick tubs are not mineral.” Our comparison of protein tubs vs range cubes covers that side of the winter feed bill.

If cows eat a mixed ration, mixing the mineral into the feed gives the most uniform intake, a point both NDSU’s drylot guide and Nebraska’s limit-feeding advice make; our drylot cow-calf guide covers that setup.

Keep cattle mineral away from other species. University of Arizona Extension’s Ionophore Toxicity in Horses (AZ1758) says about 1 gram of monensin is enough to poison a 1,000-lb horse, less than a tenth of what cattle tolerate, so check the tag of any mineral with an ionophore; and Oregon State University Extension’s sheep and goat nutrition guide notes that “sheep are sensitive to copper,” so they need a mineral formulated for sheep.

"Neighbors horses got out and decided to eat some of the BIL's cow mineral. They got some use out of the back hoe. Be careful."

— Hick, Sw mn · AgTalk thread 1200270

Plan the spring hi-mag switch now

Winter is when to plan for grass tetany, a magnesium shortfall that strikes lactating cows on lush, fast-growing cool-season grass or small-grain pasture. Nebraska’s G2340 notes that a cow’s magnesium requirement rises from 0.12% of the diet in pregnancy to 0.20% in lactation and that colostrum carries three times the magnesium of later milk, so demand peaks around calving. For cows grazing lush brome, bluegrass or small cereals, the guide suggests a 4-oz mineral with 12% to 15% magnesium; Georgia’s B895 gives 10% to 14%.

• Start weeks ahead. G2340 recommends offering the high-magnesium mineral several weeks before turnout so cows adjust and you can check intake.
• Fix palatability. Magnesium oxide is bitter; commercial mixes add molasses or corn byproducts, and G2340 suggests about 1 lb of dried distillers grains or corn per 50 lb of a custom mix.
• Keep salt loose. B895 advises against hard blocks when tetany is a risk, because adequate salt intake also helps prevent it.
• Watch fertility and weather. Georgia’s guide says tetany usually follows an extended cold spell combined with heavy nitrogen and potassium fertilization; our fertilizing hay fields guide covers potassium rates.
• Distillers diets count too. G2340 recommends at least 10% magnesium in a 4-oz mineral for lactating cows fed 20% or more distillers grains with low-quality forage.

Test before you blame the mineral

"I believe you should try to find the problem before you choose a cure."

— Albert, SE Indiana · AgTalk thread 1220737

The open-cow thread is a good example. Replies asked about body condition, bull breeding-soundness exams and calving season before anyone blamed the mineral, and a north central Missouri producer pointed to the grass instead:

"My money says mineral is not the issue with opens, but instead it's a fescue issue."

— T-rowe, North central MO · AgTalk thread 1220737

Tall fescue’s endophyte can depress reproduction on its own, as our tall fescue hay guide explains. When you do suspect mineral, test in this order:

1. Forage. Ask the lab for minerals including sulfur, molybdenum and iron, not just protein and energy. G2340 recommends sampling what cattle are actually eating, keeping dirt out of the sample, and repeating over several years.
2. Water. Sulfate at 600 ppm or more raises copper needs, and high-iron water interferes with copper, zinc and manganese.
3. The cattle. Ohio State’s summary of a 2022 Applied Animal Science review by Spears, Brandao and Heldt calls liver “the best indicator of both low and excess Cu status,” notes that plasma copper does not drop until liver stores are mostly depleted, and lists whole blood or liver for selenium (OSU Beef Letter). There is no reliable test for marginal zinc deficiency, so work with your veterinarian on which samples to take.

Frequently asked questions

Do cows need mineral in the winter?

Yes. Stored hay is often short of trace minerals and vitamin A, and late gestation is when cows build their calves’ liver reserves of copper and zinc. Provide salt plus a complete mineral matched to your forage test and region. Plain salt alone supplies almost none of the copper or zinc a cow needs.

How much mineral should a cow eat per day?

Most free-choice cattle minerals are formulated for 2 or 4 ounces per head per day, and the tag states the target. Measure actual intake by weighing what goes out over one to two weeks. Adjust with salt mixed into the mineral or by moving feeders, rather than offering a separate salt source.

Should I put out salt with mineral?

Not as a separate source when your free-choice mineral already contains salt. Nebraska Extension says separate salt reduces how much mineral cows eat. If intake runs too high, mix extra salt into the mineral instead. If cows run out, offer plain salt for a day or two, then refill the mineral and remove the salt.

Are chelated minerals worth it for cattle?

Sometimes. Nebraska Extension says inorganic sources such as copper sulfate meet most herds’ needs at lower cost, while organic forms help when mineral status must change quickly or antagonists like molybdenum and sulfur are high. Avoid copper oxide, which is poorly absorbed, and compare cost per cow per year, not per bag.

Do cows on hay need vitamin A?

Usually. Stored hay is low in vitamin A, so cows fed hay for months draw down the liver stores they built on green grass. Nebraska Extension suggests 42,000 IU a day for dry cows and 59,000 IU for lactating cows, and at least 100,000 IU for cows confined long-term.

The bottom line on mineral for cattle in winter

Mineral for cattle in winter comes down to a few numbers you can check: a target intake you have actually measured, copper and zinc in available forms at the concentrations your feed calls for, selenium under 3 mg a day, and enough vitamin A for cows living on stored forage. Start with a hay test, price the program per cow per year, and save the premium products for problems you have confirmed. The hay is still the foundation, so protect it: round bales wrapped in XES bale net wrap hold their shape from the stack to the feeder, and every pound you keep is one less pound to supplement.

Research note: We read all 33 archived AgTalk and HayTalk discussions about cattle mineral that we kept after screening the 37 with mineral in the title (369 posts, 2009–2026; 29 of the 33 threads from 2022–2026), then checked the linked Extension guides, federal rule, product label and research on October 7, 2026. Prices are what producers reported at the time, not current quotes, and post counts include questions and replies, not counts of farms. Product names appear only as farmers used them; XES does not endorse any mineral brand.

Featured photograph: Proveysieux 2018 Metrorando abc8, Patafisik, licensed under CC BY-SA 4.0, via Wikimedia Commons. A cow licking a plain salt block beside an electric fence in Proveysieux, Isère, France, in September 2018; a salt block is not a complete mineral. Image unchanged apart from display resizing.