That isn’t done for us when buying feed supplements, commodities, or by- products. We have to do that ourselves. Sometimes it involves converting ounces to grams or milligrams per pound to parts per million. I do fine as long as it’s something that I use regularly, however it I don’t use it often, it’s back to a table or internet or some cheat sheet from the past. Let’s try a few examples:

Three different protein supplements:

Cost per pound of each product might be interesting, but we’re not just buying pounds, we are attempting to buy pounds of protein. In this case, the 50 lb bag of protein is the least expensive source of protein. It doesn’t matter whether the product in the bag is pellets, meal, mini-tootsie rolls or things that look like skipping rocks! The next step is to figure out how to feed the product you have chosen. Can it be self-fed (just throw it out and cattle will eat the right amount) or will you have to distribute it in a feeder several times a week? Labor and cost of equipment may be as big a factor as the cost of the supplement itself.

Some products advise you to feed 3 grams for every 100 lb bodyweight. The first thing you have to do is somehow get a decent idea of what the animal weighs. I hope you’re better at estimating bodyweight than I am! However, let’s say that the animal weighs 600 lb. This means that we will feed 6 times the 3 grams = 18 grams to that animal. Eighteen grams is the same as 0.6 ounces --- less than 1 ounce. Good luck measuring that amount using teaspoons, coffee cans, or feed scoops! This works much better if you are preparing this for more than a few animals.

Feed tags are supposed to show the trace minerals in parts per million. It would be listed something like this:

Zinc, minimum...........................1000 ppm.

A part per million might be expressed as 1 pound in a million pounds or 1 ounce in a million ounces. Anyway you cut it, it’s a tiny amount. It also is the same as 1 milligram per 1 kilogram. This is abbreviated as mg/kg. That is the same as 1 milligram in 2.2 lb. The zinc above has 454 milligrams in a pound. If a cow’s requirement is 600 milligrams of zinc a day, one pound of this supplement has provided about 2/3 of her need, and the
range or hay she is eating only needs to provide 146 milligrams (600-454). This type of information can be quite important when you compare the labels for a product as simple as trace mineralized salt. Trace mineral salt products are NOT all the same. Some have high levels of zinc, copper, and selenium, while others have much lower levels. These three trace minerals are the most likely to be deficient in your hay, straw, or native grass range. Since zinc was one of the trace minerals mentioned, let’s use it for an example. Most of the forage that I have tested has about 18-24 ppm zinc. If the animal requires 40 ppm zinc, then our forage provides 40 to 60% of their needs. This means that the trace mineral salt needs to provide the other 50%. Zinc is important in promoting sound hooves and also plays a role in sperm quality. Both are quite important to overall performance of the herd.

How about comparing prices of different feeds for the amount of TDN:

It’s easy to see why wet corn distillers is popular when you can feed it. Also, because of the difference in price between barley and corn, we may see quite a bit more barley fed this year.

We can do the same for protein; calculating cost/lb of dry Protein.

In these examples Wet distillers grain w/ solubles is the least expensive cost per unit of TDN and Protein. This is because it is a rich source of energy and protein. Barley
is less expensive than corn when comparing TDN, but neither is very high in protein.

The protein in corn is 10% while the protein in barley is 12%, so they aren’t typically used to supplement protein when feeding straw or other low protein forage.

It is easier to compare values for a commodity such as grain, grain by-products, or hay than it is for a supplement. This is because a feed table will provide you with average values for all the nutrients. A feed supplement that is a mixture of ingredients is often hard to compare. Feed manufacturers are not required to provide the concentration of
every nutrient on the label. Take a look at the supplements below.

Which would be the better buy per unit of protein? Does the amount of NPN affect the value of the supplement? How much energy does either supplement have? Does the energy content of a supplement matter? Even if things like Vitamin E and copper are listed in the ingredients, how can you tell the amount? Will the difference between 40,000 and 45,000 Units of Vitamin A make a difference to your cattle? Why is their so much difference in the amount of selenium? These are all great questions, but I won’t try to answer them here. To determine the correct answer, we need info about the cattle, such as age, body score, sex, feeding goal. The forage that will be supplemented needs to be included. Is it meadow hay, blue grass straw, or bunchgrass range? Finally, the labor, equipment, and time involved to actually feed the supplement must be included.

Buying hay, silage, waste product or grain requires that you estimate the cost per nutrient so that you can get the most nutrients for your buck. For those of you that have and actually use the OSU Cowculator, the TDN and Protein comparisons are very easy to make.