Supplementation for Beef Cattle

From the December 2020 NDSU-VDL newsletter, a guest column by Karl Hoppe, Extension Livestock Systems Specialist, NDSU Carrington Research Extension Center:

Recently, I was visiting with a young cattle rancher about trace mineral supplementation. He was relaying his conversation with a veterinarian about the need for copper and its interaction with the immune system. I shared a copper supplementation project that was done in the early 1990s near the Missouri river that showed a drastic reduction in calf scours with adequate copper supplemented to the pregnant cow. I then realized the young rancher wasn’t born yet when this project was done.

We sometimes take for granted that people have heard the information that we feel is old news.

From a nutritional standpoint, any deficiency is a concern. However, lets plot a course for addressing nutritional deficiencies. Energy content of the cow’s diet is of most concern. Thin cows have an energy deficiency. While providing more energy seems the logical choice, due to the rumen microbes, a protein deficiency needs to corrected first. Rumen microbes need nitrogen and amino acid carbon structures to thrive and ferment feed.

There are volumes of research addressing amino acids requirements and metabolizable protein needs in beef cattle. However, for a practical, low cost on-farm approach to protein supplementation, a simple crude protein determination of the feedstuffs is very insightful.  A pregnant non-lactating cow requires only 8 to 9% crude protein in her diet.

In November, most grasses are brown and dead. Crude protein levels can range from 4 to 12% crude protein. Cows will eat the more palatable 12% crude protein feeds first. Then when pastures are getting grazed off, the lower crude protein feeds are left and a protein deficiency starts. This deficiency is slight at first but the longer the cows are grazing the low protein feed, the deficiency gets worse. The lack of protein slows up digestion by the rumen microbes and decreases rate of passage. This is a lot like the challenge of filling a water bucket that has a hole in it. The water level in the bucket will slowly go down until its empty.

If a cow is grazing 35 pounds daily of brown grass that is 7% crude protein and the cow’s crude protein requirement is 8%, she is getting 2.45 pounds of crude protein daily but needs 2.8 pounds of crude protein. A 30% protein lick tub with consumption at 8 ounces daily provides 0.15 pounds of crude protein. While a tub certainly helps, 2 pounds of a 20% protein ‘cake’ feed would provide the 0.4 pounds crude protein needed to provide an 8% crude protein ration.

In this example, 2.25 pounds of a 18% crude protein alfalfa hay would also provide 0.4 pounds of protein. A couple pounds of field peas would also provide the needed protein but need to fed in a feed bunk or losses to feeding on the ground might double the amount of peas fed (at 50% feed loss).

Providing adequate energy is needed especially during cold weather. Obviously, poor quality forages need extra energy supplementation. Thin cows are weak, have more dystocia, less colostrum and raise calves that are smaller and prone to health issues.

When feeding poor quality forages, vitamin and mineral supplementation is needed at higher amounts.

With good quality feeds, a safe assumption is that the feeds will provide at least half of the vitamin and mineral needs and a good quality mineral mix is formulated to provide the rest. With poor quality feeds, a mineral mix needs to provide almost all of the vitamins and minerals. This can be accomplished by feeding double the amount of the existing mineral or finding a mineral mix with double the concentration. In other words, feed 4 ounces of mineral instead of 2 ounces or find a mineral that has twice the concentration to be fed at 2 ounces.

Brown forages are usually lacking in vitamin A as well as most major and microminerals. I suggest doing feed analysis on sampling feeds for Vitamin A analysis. However, please be aware that the coefficient of variation of vitamin A lab tests can be quite high. Most feed companies will formulate for higher vitamin A concentrations than listed on the guaranteed feed analysis to offset lab test variation and the loss of vitamin A while feeds are in storage.

North Dakota soils are low in copper and most feed stuffs will provide a report of less than 6 ppm copper. NRC Beef Cattle Nutrient recommends 10 ppm copper in the beef cow diet. Subclinical deficiencies of copper are widespread in herds that do not provide mineral supplementation.

Rations that contain high levels of copper product feeds like distillers grains, wheat midds and grains, will need calcium supplementation to avoid urinary calculi.  The high phosphorous concentrations of DDGS, wheat midds, and high grain diets create an incorrect calcium to phosphorous ratio. A ratio of 2 calcium to 1 phosphorous is indicated.

Diets high in sulfur may create polio symptoms. Removing the sulfur source or providing a different water source may help. Additional zinc, selenium and vitamin E are also usually needed in the mineral mix. Be care of interactions between minerals that can interrupt bioavailable. Chelated or organic forms are more bioavailable and might be needed to offset deficiencies. Liver biopsies can provide insight to mineral status of the animal. However, due to tremendous individual variation, multiple animals should be sampled for evaluations herd sufficiency.

Providing a mineral supplement can help reduce mineral deficiencies. Providing directly into a totally mixed ration is the best approach to ensure adequate intake. Free choice supplementation only helps the cattle that actually consume the mineral.

View the newsletter (and find a printable pdf of this article) here.