Re: selenium info

[Mia Nalias <arabs2go@yahoo.com>]

"R. M. Raymond" <keishastar@juno.com> wrote:
>
> dfletche@gte.net writes:
> From NRC, adequate concentration: 0.1 mg/kg of overall diet, maximum
> tolerable dose 10 mg/kg of overall diet.
> 
> CMKSAGEHIL@aol.com  writes:
> Oregon State's recommendations--daily requirement for 1000-lb horse of
> 8-10 mg per day, with chronic toxic levels of 60-90 mgs per day.
> 
> can be measured a number of different ways: parts per million, mg/lb,
> microgram/lb.
> 
> Does anyone know how to convert mgs to parts per million?  I was
reading
> a mineral supplement bag today, and it has 36ppm.  It didn't say per
> ounce or per pound or even serving.  It did say to feed free choice,
or 2
> oz/day. 
> 
> [Rose]
> _______

You can't convert mgs to ppm. One is a unit of mass (mg), the other is
a concentration. 1 ppm = 1 mg/kg, so your feed is 36 mg/kg. If you
want to achieve a daily intake of 8 mgs for a 1000 lb horse, you must
feed the mass of feed that provides this dose. For example, if you
assume that none of your other feeds contain selenium, you would feed
about 220 mg (0.5 lb) of your 36 mg/kg feed. 

To feed 2 oz is probably assuming there is Se in your other feeds, and
that you have an idle mature horse, and I think Heidi will confirm,
probably underestimates how much Se a working horse needs. I wouldn't
suggest exceeding the recommended dosage though, not knowing anything
else about the feed.

It's so much easier when we're supplementing to have someone provide a
daily requirement (thanks Heidi) than to say your feed should be 'X'
concentration.  How many people know the concentration of Se in their
pasture or hay? While it's important to have some idea so that we
don't oversupplement, the daily requirement is the more practical
number for most of us.

Mia

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