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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

The seasonality of vitamin D levels in cattle

A recent study assessed the seasonality of 25(OH)D levels in cattle, a sun exposed population.

The seasonality of 25(OH)D levels are well known in many populations. However, the seasonality of 25(OH)D in a sun-exposed population is not well known. That is, what is the seasonal variation in 25(OH)D of those who live and work in the sun?

We don’t know the answer for humans but we do for cattle! Dr. Tim Reinheardt of the USDA assessed seasonal vitamin D levels of 195 steers and heifers at latitude 41 degrees North over a two-year period.

Casas E, Lippolis JD, Kuehn LA, Reinhardt TA. Seasonal variation in vitamin D status of beef cattle reared in the central United States. Domest Anim Endocrinol. 2015 Mar 21;52:71-74.

In late Spring, mean 25(OH)D levels of the cattle were 26 ng/ml. By late summer those levels were about 49 ng/ml, and by September the levels were up to 65 ng/ml.

Then, the vitamin D levels began falling to about 55 ng/ml in October, and continued to decline to about 15 ng/ml by the end of winter with 28% of the cattle having levels below 10 ng/ml.

These cattle received supplemental vitamin D in their feed but only about 2 IU/KG/day. The authors called for additional feed fortification, especially in winter.

One cannot compare the 25(OH)D levels of different species. However, it is interesting to note that the vitamin D status of cattle ranges are similar to the known ranges in humans (about 60 ng/ml for lifeguards at the end of summer and 15 ng/ml levels for many populations at the end of winter).

It appears cattle and perhaps sun-exposed humans experience drastic seasonal changes in their vitamin D status at latitude 41 degrees North.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

2 Responses to The seasonality of vitamin D levels in cattle

  1. allometric24 says:

    There is an interesting discussion on the ways in which various animals, including cattle, get their vitamin D here http://www.msdiscovery.org/news/news_synthesis/10213-beyond-reasonable-doubt-vitamin-d-piece-ms-puzzle

    • Frank says:

      Santa Cruz Biotechnology, an international company which ships most inventory out of Paso Robles, CA (recently moved HQ to Texas), has an Animal Health side to the company since the owner’s wife also owns San Juan Ranch and does the cowboy and ranch thing. They have a number of products, including vitamin d as an oral gel applicator intended for bovine, ovine, and caprine (cows, goats, and sheeps).