Post by flintfootfilly on Apr 21, 2012 9:20:42 GMT -1
Going on from my original thread asking for any thoughts on poor performance, work intolerance, elevated muscle enzymes in my gang: dalesfans.proboards.com/index.cgi?board=vet&action=display&thread=22159.....
We're now looking at the possibility of it being a selenium deficiency.
It's known that vitamin E deficiency and/or selenium deficiency can result in muscle damage, and so this was something which was mentioned fairly early on. However, we thought that both these things were covered, because I actively supplement at least 1,000iu/day of vitamin E (usually in the form of gelcaps, but more recently in a feed balancer), and the forage analyses that I have had done on my hay and haylage for the last 2 years showed selenium levels as "average" or "high". So we didn't pursue that avenue..... til now.
It turns out that the "average" and "high" commonly found on forage analyses from different labs do NOT relate to whether the level is average or high for feeding to horses/ponies. It seems they relate to whether the levels usually found in grass/hay...... which of course doesn't take account of whether there are any widespread excesses or deficiencies.
Anyway, looking at the figures more closely, my forage provides 0.05mg/kg , and this works out as 0.34mg (edited because I put the required supplement figure before, rather than the actual amount provided in my hay, sorry) selenium per pony in each day's ration.
NRC (National Research Council) in USA recommend 1mg per day for a 500kg horse at rest or in light work. So, already we have a deficiency.
Interestingly, I've looked at various forage analyses done in different parts of the UK and of the 13 analyses posted (voluntarily by other horse owners), only 3 of them provided adequate amounts of selenium.
I'm afraid I've tended to think that if the ponies were doing very little work, and not either infoal or growing youngsters, then forage should provide pretty much all they need. But already, this is showing not to be the case.
I've usually added some feed balancer but at a low level (one friend had been advised by one of the feed manufacturers that you could feel half rations of balancer to native ponies in light work). Well, looking more into the levels actually contained in different balancers, the variation is HUGE, and some contain inorganic selenium (sodium selenite) which has been shown in various papers to be less available to horses than organic selenium (selenium yeast).
Have come across one paper which looks at the effect of supplementing organic yeast at various levels, as well as inorganic yeast. Showed a really interesting graph of how CK (one of the muscle enzymes) increased over around 4 months of supplementation to pretty much reach a plateau. It also showed that over 70% of the horses were found to have levels of selenium counted as deficient, although none showed clinical signs of a deficiency.
Other things I've come across are that selenium deficiency has been associated with mares retaining their afterbirth when foaling. No scientific papers on this, that I can find, but it seems widely accepted. I've bred 3 foals....... guess how many of their mums had to have the vet out for a retained placenta? YUP, you guessed right.....3!!!
There's also a paper on selenium deficiency causing muscle degeneration in 3 different horses studied, who all showed signs of dysphagia (problems chewing/swallowing food). Interestingly, I had asked to vet for an opinion on why one of my mares is slurping saliva, and we'd not come up with a conclusive answer - batches of hay and haylage have changed, and yet the excess salivation still continues; no difficulty actually eating, but hmmmmmmm, could it be related?
Anyway, the long and short for me at the moment is that my vet came and took bloods from the 2 worst affected ponies yesterday. They're going to be checked for vitamin E levels as well a whole blood selenium (which apparently gives a better indication of the long term selenium status, whereas plasma selenium only gives a short term picture). Results will probably take up to 10 days.
About half the balancers that I've looked at include the NRC recommended level of selenium when fed at the full ration recommended by the feed manufacturer. The others are too low.
Of course, the other thing that I'm bearing in mind is that selenium can be toxic, fatal, in too high a quantity, so it's important that I supplement according to the levels that are known to be in my ponies' rations.
And the other thing I'm discovering is just how badly matched a lot of feed balancers seem to be in relation to the various major and trace minerals, when compared with my actual forage analyses.
Would be interested to read whether anyone has had a confirmed selenium deficiency in any of their gang, and any lessons learned.
Will update on how we progress - blood results etc.
Do you know, all I'd like to do is get on and enjoy riding my ponies....... but instead I seem destined to have to carry out lots of maths, lots of internet searches and have lots of vet visits and blood tests!!
Sarah
We're now looking at the possibility of it being a selenium deficiency.
It's known that vitamin E deficiency and/or selenium deficiency can result in muscle damage, and so this was something which was mentioned fairly early on. However, we thought that both these things were covered, because I actively supplement at least 1,000iu/day of vitamin E (usually in the form of gelcaps, but more recently in a feed balancer), and the forage analyses that I have had done on my hay and haylage for the last 2 years showed selenium levels as "average" or "high". So we didn't pursue that avenue..... til now.
It turns out that the "average" and "high" commonly found on forage analyses from different labs do NOT relate to whether the level is average or high for feeding to horses/ponies. It seems they relate to whether the levels usually found in grass/hay...... which of course doesn't take account of whether there are any widespread excesses or deficiencies.
Anyway, looking at the figures more closely, my forage provides 0.05mg/kg , and this works out as 0.34mg (edited because I put the required supplement figure before, rather than the actual amount provided in my hay, sorry) selenium per pony in each day's ration.
NRC (National Research Council) in USA recommend 1mg per day for a 500kg horse at rest or in light work. So, already we have a deficiency.
Interestingly, I've looked at various forage analyses done in different parts of the UK and of the 13 analyses posted (voluntarily by other horse owners), only 3 of them provided adequate amounts of selenium.
I'm afraid I've tended to think that if the ponies were doing very little work, and not either infoal or growing youngsters, then forage should provide pretty much all they need. But already, this is showing not to be the case.
I've usually added some feed balancer but at a low level (one friend had been advised by one of the feed manufacturers that you could feel half rations of balancer to native ponies in light work). Well, looking more into the levels actually contained in different balancers, the variation is HUGE, and some contain inorganic selenium (sodium selenite) which has been shown in various papers to be less available to horses than organic selenium (selenium yeast).
Have come across one paper which looks at the effect of supplementing organic yeast at various levels, as well as inorganic yeast. Showed a really interesting graph of how CK (one of the muscle enzymes) increased over around 4 months of supplementation to pretty much reach a plateau. It also showed that over 70% of the horses were found to have levels of selenium counted as deficient, although none showed clinical signs of a deficiency.
Other things I've come across are that selenium deficiency has been associated with mares retaining their afterbirth when foaling. No scientific papers on this, that I can find, but it seems widely accepted. I've bred 3 foals....... guess how many of their mums had to have the vet out for a retained placenta? YUP, you guessed right.....3!!!
There's also a paper on selenium deficiency causing muscle degeneration in 3 different horses studied, who all showed signs of dysphagia (problems chewing/swallowing food). Interestingly, I had asked to vet for an opinion on why one of my mares is slurping saliva, and we'd not come up with a conclusive answer - batches of hay and haylage have changed, and yet the excess salivation still continues; no difficulty actually eating, but hmmmmmmm, could it be related?
Anyway, the long and short for me at the moment is that my vet came and took bloods from the 2 worst affected ponies yesterday. They're going to be checked for vitamin E levels as well a whole blood selenium (which apparently gives a better indication of the long term selenium status, whereas plasma selenium only gives a short term picture). Results will probably take up to 10 days.
About half the balancers that I've looked at include the NRC recommended level of selenium when fed at the full ration recommended by the feed manufacturer. The others are too low.
Of course, the other thing that I'm bearing in mind is that selenium can be toxic, fatal, in too high a quantity, so it's important that I supplement according to the levels that are known to be in my ponies' rations.
And the other thing I'm discovering is just how badly matched a lot of feed balancers seem to be in relation to the various major and trace minerals, when compared with my actual forage analyses.
Would be interested to read whether anyone has had a confirmed selenium deficiency in any of their gang, and any lessons learned.
Will update on how we progress - blood results etc.
Do you know, all I'd like to do is get on and enjoy riding my ponies....... but instead I seem destined to have to carry out lots of maths, lots of internet searches and have lots of vet visits and blood tests!!
Sarah
