Re: Nutrition

[Susan Evans Garlinghouse <suendavid@worldnet.att.net>]

Lysane Cree wrote:
> 
> I have a couple of questions about nutrition:
> 1)How much selenium is
> too much? And what does too much selenium do exactly?

Maximum tolerable levels in horses is 2 mg/kg of diet.  Toxic levels are
around 3.3 mg of selenium per kg of body weight.  Chronic (as in getting
too much but not yet lethal) shows up as hair loss, especially around
the mane and tail and cracking of the hooves around the coronary band. 
A lethal dose looks alot like an extreme colic, and/or blindness,
staggering high HR, diarrhea, etc.

Something else to keep in mind is that selenium levels in hay are highly
variable throughout the country.  The NW, NE, portions of the Great
Lakes areas and SE tend to be low in Se;  parts of the SW and throughout
the Midwest can be high in Se.  Ask your feed store where your hay is
coming from and if it's coming from an area that you suspect might be
high in Se, give your country extension agent a call, they'll be able to
tell you what representative Se levels are for that level.  You can also
get a hay sample analyzed, but that won't help much if next month's load
of hay comes from a different area.

You might also consider that if you're feeding a balanced feed such as
Omolene, plus good quality hay, it's unlikely you need an additional
vitamin-mineral supplement on top of that.  The most common source of Se
poisoning does result as feeding too much through oversupplementation in
one form or another.  However, you said you're not feeding much, so it's
probably unlikely you're pushing the envelope on selenium.  Just don't
go overboard on too much of the vit-min supplement.





> 2)I have purchased some Farrier's Magic (same idea as Farrier's
> Formula) to add some biotin in my horse's diet. There is also copper
> and zinc in Farrier's Magic. Now, my regular vitamin/mineral supplement
> also has copper and zinc in it. I have read that copper and zinc need
> to be balanced (in a similar fashion as calcium and phosphorous need
> to be balanced). Again, numbers are calculated as to what is in the
> entire container of Farrier's Magic (an 11 pound container).
> The scoop in that case has written on it 60 cc and you are supposed to
> feed 4 of those scoops/day. My question is whether I should be
> feeding both the Farrier's Magic and the vitamin/mineral supplement
> at the same time?  or should I not feed the vitamin/mineral supplement
> when I feed Farrier's Magic (or vice versa)?
> Help!

You're not feeding enough of either supplement for it to be a concern. 
Both sources are balanced (I assume) in their Cu-Zn levels, and assuming
you're not feeding entire bucketfuls, excessive levels aren't a
problem.  Don't lose sleep over it.  However, since all you said you're
looking for is a source of biotin, you might try looking around and
finding a source of JUST biotin (more or less) without having to pay for
more copper, zinc, etc that your horse doesn't need more of.

Hope this helps.  Stay warm.

Susan Garlinghouse