02/24/2026
INSTALLMENT #5-c- -Selenium & Vitamins E, D, and A
Does your "sheep" mineral contain selenium?
Do you operate in a selenium deficient area?
Do an internet search for selenium deficiency map, and take your choice for credibilty.
Selenium(Se)- If you live in a region which is considered Se-SUFFICIENT( see a map), and you believe you get a response to individual treatments with selenium-vit E supplements, you may be treating a vitamin E deficiency, not selenium.
Vitamins- Most, if not all nationally merchandized "sheep" minerals have vitamins A, D, and E added to the salt, limstone, etc. in the mix. Sounds good, right? They're charging for it, you're paying for it, and you won't have to worry about deficiencies of those vitamins, right? Maybe not.
When vitamins A & E are in contact with salt and calcium, the effective half-life is a matter of a few weeks. The major ingredients in "sheep" minerals usually include salt and calcium. So, if your sheep are consuming those vitamin-mineral supplements within a few weeks of manufacturers mixing, you're good. How long did those bags of mineral set in the warehouse, feedstore, your barn, your mineral feeder, etc. before it was consumed?
Based on NRC, 2006, recommendations, the vitamin supplementation levels provided by several "sheep" minerals (at least the ones I looked at) may be:
Vitamin A - Over-supplemented at several times the requirement level,
Vitamin D - Supplementation of sheep exposed to natural sunlight, on natural diets will not likely be needed, ,and,
Vitamin E - Content may meet 1/3rd, or less of the sheep's needs, assuming the vitamins have not degraded by the time of consumption.
Approved selenium supplementation in Se-SUFFICIENT regions (see map), and unnecessarily high levels of vitamins A and D supplementation probably do no harm. However, inadequate vitamin E supplementation can cause misdiagnoses (thinking a response is due to SE, not vit E) of a problem. The condition may have been prevented with appropriate, adequate levels of vitamin E in the salt-mineral, and/or feed supplement. An ounce of prevention(vit E) is worth a pound of cure(Selenium-vit E)
Sheep grazing on green growing pasture/forage likely will have no need for supplemental vitamins. However, vitamin A and E supplementation should be provided during drylot feeding, and extended dormant season and drought grazing conditions.
Adding selenium at approved levels to sheep rations could potentially have a negative effect, if the sheep are in one of those pockets of potential selenium toxicity(see a map), or animals are being individually dosed with profilactic selenium. In which case, animals may be shoved into chronic toxicity with some specific clinical signs that could be mistaken for some other cause. Do an internet search for chronic selenium toxicity (Cornel Univ.), and think hoof issues with Boer goats.
Vitamin E, and selenium have a supportive role in the animals' metabolism. Before selenium's function was fully understood, and routine selenium mineral-supplementation was approved I worked in a true selenium deficient region. It was not uncommon for 5% to 8% of a January-February born lamb crop to develop White Muscle disease. At the time, preventatives/treatments for the condition was feeding wheat which had been raised in the Great Plains (selenium), and/or large doses of vitamin E.
Anyone who thinks they get a boost, or effect from individual dosing of selenium-vitamin E should consider the boost may be due to correction of a vitamin E deficiency. That deficiency may have been prevented by adequate bio-effective vitamin E dietary supplementation which would have spared the animal the pain and lost productivity. It would have also prevented the cost of the individual treatment material, labor, and time.
Check your "sheep" mineral. Based on the labeled consumption level, calculate the expected daily vitamin E consumption. NRC, 2006, recommends a 150 # ewe, or goat carrying twins in late gestation requires 392 IU/hd/day.
What level are your's getting?
