more on vit E/Se/Balancing rations

Let's move onto Selenium.

Selenium

Selenium has a very narrow range of "OK".  Too little is bad, too much is bad.  This scares a lot of people.  Talk to knowledgeable people in the animal medicine field about selenium supplementation in horses and the first thing I get is a look of concern, followed by "did you hear about the polo ponies?".

The polo ponies had an overdose of Se given by IV.  Not orally.  Someone made a decimal point error the ponies received many many many times the safe amount of Selenium.  I asked every nutrition professor and nutrition guest lecturer of whether they had EVER heard of a Selenium overdose that occurred in horses as a result of ORAL supplementation.  The answer has been no.

That being said, if you are going to supplement Se, keep in mind that most feeds have Se in them and it can add up very quickly if you are feeding 5 pounds of this and 2 pounds of that and scoop of that over there.....I try to keep my feeding routine very simple (not feeding a lot of different feeds or "complete" supplements), supplement with a product from a company I trust, AND periodically test Farley's Se blood levels.  Personal research has made me comfortable with a level of 0.3ppm or above in endurance horses.  There's nothing published that I can find, and no one I've talked to in the nutrition world has been able to give me a definitive answer.  However, from my research, and people I've talked to, and personal experience, I shoot for a blood ppm level of 0.30-0.45.  Considering that the upper safe level is 0.5ppm ("normal" is 0.08-0.5ppm *I think*  Need to go back and double check the range) I'm operating at the top of the "safe" range and need to be careful.  I don't always get my hay from the same sources although my other feeding remains fairly constant and depending on whether the hay is local or shipped from the NW (Oregon, Washington etc.) the Se levels can vary GREATLY, which is why it is worth my time to keep an eye on Farley's Se levels.  Even though in my opinion oral supplementation is generally safe, especially if you have a baseline Se value for the horse and you know you aren't sitting at 0.45 or 0.5, if your hay source varies AND you are feeding a multitude of different feeds/supplements/mashes etc., I would DEFINITELY be testing blood levels regularly if I decided I wanted to supplement.

Selenium is "vitamin E" sparing, meaning that when you have sufficient levels of Selenium, vitamin E doesn't get "used up" as fast.  Selenium, like Vitamin E participates in the antioxidant process and neutralizes radical oxygen species (ROS).

Radical Oxygen species
I thought that it might be useful to briefly discuss what ROS's do since both vitamin E and Selenium are both neutralizing them and it seems that this actually might be relevant to endurance horses --> since apparently deficiencies may be linked to all sorts of things, and it is my belief that one part of why Farley tyed up in 2010 was related to being deficient!

ROS are generated by inflammation, radiation, oxygen toxicity, chemicals, and reperfusion injury.  They alter the membranes of cells in ways that decreases stability and maintenance of permeability --> which leads to collapse of cell structure and cell rupture.  This is BAD.  There are several defenses against ROS, one of which is antioxidants.  Vitamin E "quenches" the ROS.  The "used" vit E is then regenerated by vit C.  Glutathione (another antioxidant) regenerates vit C.  Selenium reacts with the product that vitamin E changed and changes it further into something harmless (water I think).

So, as you can see, Se and Vitamin E participate in the same process, BUT they aren't necessarily directly linked.

Deficiencies of vit E and Selenium

Now that I've thoroughly bored the vast majority of my readers, let's go on to conditions that cause deficiencies!!!!!!!

Even though I explained (in probably unnessarily complicated biology) that Se and vitamin E and not necessarily biologically linked, except as participating in the same cycle, deficiencies of Se ARE linked with vitamin E deficiencies!

Here's the short list of conditions that create deficiencies that I thought relevant to endurance
-Consumption of grains or forages deficient in Se of vitamin E (for horses, almost everything we feed them is vitamin E deficient.  Most feeds are OK in Se, but depending on where you live your forage may or may not be OK).

-diets that include unsaturated fatty acids (I mentioned this in my fat post.  Feeding fish oil requires an increase in vitamin E!!!!!!!!  IMO choose a different oil to feed your horse....)

-stress and high rates of production (ummm......IMO there is just a *wee* bit of stress associated with running 50-100 miles.  What do you think?)

-Damage to tissues (oh I'm sure horses coming off of a 100 *never* have damaged tissues......or muscle repair....or soreness....or any other type of tissue repair going on....)

Supplementation
I've already touched on Se supplementation, but a note about vitamin E supplementation: generally regarded safe.

As with anything you can over do it, but that 3-5K I/U range that mentioned in my last post is what I consider appropriate for my endurance horse.

I'll get into the specifics of what I feed and why, and what I'll be switching too in a next post :).

Just a note: There are tests that you can do to test levels of both Se and vitamin E, however the only one I've seen done in my experience is the Selenium test, since that's the one with the narrow margin of safety.  With more wiggle room on the vitamin E, I just don't see the sense personally to spend the money.

To be continued!.....