Don't Take Vitamins for Granted

Livestock Update, November 2003

Mark L. Wahlberg, Extension Animal Scientist, VA Tech

Cattle normally do not need much in the way of supplemental vitamins as long as they are eating a diet consisting of green forage. This forage may be either in stored form or as pasture. The key vitamins of concern with cattle are:

• Vitamin A - Derived from carotene in forages. When consuming a diet containing large amounts of carotene cattle can store extra Vitamin A in their liver - enough to provide their needs for up to 2-4 months. Vitamin A deficiency can occur under these conditions
• High grain diets
• Bleached pasture or hay grown during drought conditions
• Feeds that have received excess exposure to sunlight, air, and high temperature
• Feeds stored for a long period of time
• Feeds that have been mixed with oxidizing materials, such as minerals

In addition, forages which are more advanced in maturity have a greatly reduced level of carotene, thus much less Vitamin A. It would seem that much of the hay made this year contains a lower level of Vitamin A activity than normal.

Vitamin A can be added to feeds. It can also be injected into cattle. Cattle require at least 30,000 International Units (IU) of Vitamin A daily.

• Vitamin D - normally synthesized by cattle exposed to sunlight or fed sun-cured forages, so deficiency rarely occurs. Vitamin D cannot be stored in the body. It is involved with the metabolism of Calcium and Phosphorous. Deficiency results in signs similar to those of Calcium deficiency, such as bone deformities, muscular weakness, and weak or dead calves.

Cattle require about 3000 IU of Vitamin D daily. It can be added to feeds and also injected.

• Vitamin E - a vitamin closely associated with the mineral selenium. Like Vitamin A, the amount of Vitamin E is lower in forages that are more mature. Vitamin E levels in feeds are reduced when exposed to heat, moisture, trace minerals, nitrates, and higher levels of unsaturated fatty acids. Deficiency is noticeable in younger animals as general muscular dystrophy and weakness, impaired suckling ability, heart failure, and paralysis. The syndrome is called white-muscle disease.

Cattle require 50 to 150 IU daily. It can be fed or injected. Injectible Selenium products also contain Vitamin E.

Toxicity of these 3 vitamins is unlikely. The risk of toxicity is least with Vitamin E, in fact toxicity of cattle to Vitamin E has not been demonstrated. Vitamin D toxicity results in high blood Calcium and abnormalities in bone mineralization. Vitamin A toxicity is also quite rare, in part because the rumen microbes are able to break down Vitamin A that is consumed in the diet directly.

Based on this background information these recommendations concerning vitamin supplementation for cattle have been developed:

• When consuming abundant green, leafy forage the diet should provide adequate amounts of these vitamins to cattle.
• When mature, weathered forage is being fed, especially for an extended period of time (more than 1 month in duration), these vitamins should be supplemented to cattle.
• When cattle are consuming higher levels of grain, especially in confinement, then these 3 vitamins must be added to the diet.
• Because vitamins are broken down during storage, especially when in the presence of mineral products, deficiency may still occur even though a product label indicates the presence of these vitamins in a trace mineral developed for cattle.

Trace mineral mixes are the typical form in which vitamins are supplemented to cattle. If cattle consumed an average of 4 ounces of mineral daily, and using the required amounts of vitamins described previously, we can calculate the concentration of these vitamins which are needed in trace mineral mixes. Those calculated values are approximately: Vitamin A = 120,000 IU / pound of product, Vitamin D = 12,000 IU / pound of product, and Vitamin E = 150 to 500 IU / pound of product.

However, due to the several reasons listed above, the recommended levels of vitamins in trace mineral products for cattle should be quite a bit higher. Toxicity is very unlikely, vitamins break down in storage, and intake of mineral products is quite difficult to accurately predict.

Recommended Levels of Minerals in Cattle Trace Minerals
(For Cattle Consuming Pasture and Hay Based Diets)
Vitamin A at 150,000 to 200,000 IU per pound,
Vitamin D at 20,000 to 50,000 IU per pound,
Vitamin E at 200 to 250 IU per pound

These levels in mineral products should provide adequate vitamin supplementation even when cattle are consuming over mature, lower quality forage for long periods of time. If cattle are being fed in dry lot, especially with rations containing high grain levels, a different approach to vitamin supplementation should be followed. Consult with a nutritionist when feeding cattle in these situations.

Because of the close association of Vitamin E and Selenium, you should also be looking at that item on the feed tag of a product you are considering feeding. Many Virginia producers operate on soils which are low in Selenium, thus the forages grown on those soils are also low in Selenium. Cattle should be fed a trace mineral which contains from 25 to 50 ppm of Selenium (also expressed as 0.0025 to 0.0050%).

Vitamins are not expensive to include in a mineral product. Because the hay that will be fed this winter may be quite a bit lower than normal for vitamins, deficiency may occur if proper vitamin supplementation is not provided.

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