In last month’s issue of Progressive Cattleman, we discussed five myths believed by some cow-calf producers. Below are the second five of my top 10 beef cow-calf nutrition myths. Click here to read the first five of the top 10 beef cow-calf nutrition myths.

Midla lowell
Dairy Technical Services Veterinarian / Merck Animal Health

Myth 6
Protein tubs are just an expensive way for lazy dudes to supplement cows. Mature cows don’t need much protein in their diet anyway.

While it is true that excess protein above requirement is “wasted” in the rumen (see below for explanation of “wasted”), adequate dietary protein is particularly important to cows in mid-gestation to late gestation on a hay-based or forage-based diet.

Adequate protein is necessary for the microbial population in the rumen to flourish.

That is, bacteria need protein to build more bacteria. More protein (up to a point) thus leads to greater numbers of bacteria in the rumen. More bacteria in the rumen leads to better fermentation and thus more complete extraction of energy from the forage.


This is particularly critical if the diet consists of poor-quality hay. But it is important to note that supplemental protein can often help cows derive more benefit from moderate-quality forage as well.

Excess protein is “wasted” when there is more protein in the diet than the rumen bacteria can use for bacterial cell wall synthesis, bacterial DNA replication, bacterial growth, etc. When this occurs, the bacteria simply transform the protein to be used as energy.

Generally, energy supplements are cheaper than protein supplements for cattle. Thus, feeding excess protein should also be avoided. One interpretation of all of the above is that it validates what nutritionists seem to be so fond of telling us – that we should have our forages tested.

That way we can then spend money to supplement protein if necessary … but only if necessary based upon the results of the forage test.


  • Adequate protein is necessary during late gestation for calf growth.
  • Adequate protein is necessary during late gestation for colostrum synthesis.

  • Protein tubs are generally a comparatively expensive source of protein. It is often likely that an alternative less costly source of protein can be found (e.g., distillers grains).

Myth 7
My cows need an expensive mineral with magic ingredients.

Minerals are no different than anything else required for life. A great example is water: too little and you die; too much and you die. As long as you are somewhere in the “adequate” range, then additional mineral is not likely to be of benefit.

Health benefit derived from different levels of nutrients in the diet

Note in Figure 1 that the curve is flat over the “adequate” or “optimum” range. A great example that involves cows is expensive minerals complexed to an organic carrier.

Notwithstanding that such minerals are indeed generally more bioavailable to the cow, your cows may or may not need the additional level of mineral.

There are, of course, situations in which beef cows benefit from and should receive minerals complexed to an organic carrier. The point above is simply that this is not always the case. Watch the cost-benefit. If, for example, your cows are receiving some daily grain, then include adequate non-organic mineral in the grain mix.

This has the advantage of being cheaper as well as, given cow-to-cow variability in consumption of free-choice mineral, making it more likely that every cow gets the right amount every day, as long as you have adequate bunk space for each cow to eat and wait to dump the feed until all of the cows are there.

Myth 8
If it is in the bag, then the cow gets it. That is, the amount of each mineral listed on the side of the bag is the amount absorbed and utilized by the cow.

There is variation in availability of what is in the bag to the cow. Zinc sulfate has a different bioavailability to the cow than zinc carbonate, which has a different bioavailability to the cow than zinc oxide, which has a different bioavailability to the cow than zinc methionine, which has a different bioavailability to the cow than zinc chloride, etc.

The manufacturer of the mineral can list the number of grams of zinc in the bag by weight of the zinc no matter what the zinc is attached to. Thus, if zinc oxide is cheaper for the company to source than zinc sulfate, then they can put zinc oxide in and still claim the same amount of zinc.

When you are comparing bags of mineral down at the local feed store, and one bag is cheaper than the other and has the same number of grams of zinc, then why not buy the cheaper bag? The reason is that the cow will not absorb/receive the same amount of zinc. The same holds for other minerals.

Methods of getting around this issue:

  • Buy name-brand mineral from a company with a reputation to uphold – thus you can be reasonably assured that what is in the bag is in there in an amount and form that will likely meet the cow’s requirement.

  • Consult a nutritionist.

Myth 9
My cows don’t need mineral supplementation.

Corollary to Myth 9
Mineral costs a lot, and every time I put a bag out, the cows just eat it in a day or two, so I just quit putting it out.

See Figure 1. Pasture-based and forage-based winter feed almost never have exactly the right balance of mineral for cows. It would be a rare situation in which no vitamin or mineral supplementation was necessary.

While profit on a beef cow-calf operation has historically depended quite a bit upon controlling expenses, don’t be a cheapo.

Myth 10
My cows are eating more mineral than usual, so they must be deficient in something.

Cattle will seek sodium (salt). Cattle will not generally seek other minerals (with the possible exception of calcium or phosphorus in the unlikely circumstance of extreme deficiency). Cattle that are cobalt-deficient or selenium-deficient will not go find a rock with cobalt or selenium in it and lick it.

Cattle that are cobalt-deficient or selenium-deficient don’t know that they are deficient any more than you would know you were deficient in cobalt or selenium … nor do they know what rocks contain cobalt or selenium any more than you do.

This is also a reason to, generally, not provide white salt in addition to a balanced mineral. The amounts of all of the other minerals besides the sodium in a given balanced mineral are in proportion to the sodium.

Cattle will generally regulate their consumption of the balanced mineral based upon the sodium. So if sodium is available elsewhere, then they might not consume any of the balanced mineral at all and thus not get any of the other minerals.

I greatly respect the breadth and depth of knowledge that nearly every cattleman has – building a straight fence, predicting the weather, fixing a tractor, agronomy, genetics, EPDs, veterinary medicine, animal nutrition, etc., etc., etc.

However, it is important in life to know one’s limitations. I am a veterinarian. I am also a cattleman. I can build a straight fence, fix a tractor and do many other things well enough to get by.

But I know my limitations. When it comes to electricity, I can reconnect the white wire to the white wire and the black wire to the black wire. If it gets any more complex than that, then I hire an electrician.

Electrical work just is not in my repertoire. Similarly, unless you have an advanced degree in animal nutrition, it might just pay for you to consult with a nutritionist regarding your herd’s nutrition.

After capital costs associated with farm/ranch ownership, feed is generally the biggest expense on a cow-calf operation. If a consulting nutritionist does not make you more money than he or she costs you, then hire a different one next year.  end mark

Lowell Midla
  • Lowell Midla

  • Assistant Professor College of Veterinary Medicine
  • Ohio State University
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