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RE: [RC] Blood test levels - heidiIs this 200 to 250 target for serum, plasma or whole blood Se? Whole blood runs 25 to 28% higher. I assumed (?) the test results posted were serum because E was tested. The labs I always used preferred to do whole blood Se, but always told us that it was more accurate, not that there was any consistent difference. It's known in other species and confirmed in horses (KER) that exercise causes release of Se from red cells and subsequent increased urinary excretion. Like most nutritional studies, this was done using thoroughbreds so tells you nothing about an endurance horse's needs, i.e. with prolonged exercise, but there's a strong possibility that losses increase as exercise duration increases, attenuated somewhat by decreased urine production. Could be why performing horses do better with higher levels... Just a word about Se yeast. I'd be cautious about assuming there is a greater safety margin with Se yeast. True story. Mature Icelandic horse (light use), living in New England, selenium deficient, started on 2 mg/day of Se yeast. Horse moved to Colorado. Selenium supplementation continued at the same dose. Within six months, mane and tail falling out. Forage was tested and contained 0.5 ppm Se. Horse was getting maximum of 15 pounds/day for an intake of organic Se from the hay of 3.4 mg/day from this source, 2 mg from the Se yeast, no other Se supplemented items in the diet. Se yeast stopped. Hair regrew. Unfortunately, she didn't get Se testing on the horse but it was seen by a vet, no skin pathology/infections found and hair regrew after stopping the Se yeast. Too bad about not having the bloodwork--that would have been interesting. In most horses, it takes 60-90 mg or more per day over a prolonged period (a couple of months) to get signs of toxicity. (That's slightly less than 10x the daily recommendation of 8-10 mg, to put it in perspective. And of course, that was average-sized horses--you'd have to "pro-rate" that for a smaller Icelandic, I would think.) I would wonder about breed differences--perhaps Icelandics are more efficient with their Se and less tolerant of excesses than other breeds?? Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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