In uk.rec.gardening Charlie Pridham wrote:

"Bill" wrote in message
...
In message , Mike
writes
Horses, ponies, donkeys and other livestock shouldn't be on motorway
verges. If they are then they and their owners deserve to die.

So FFS get those animals off the motorway verges and into the fields
where they belong.



If any one knows the Black Cat roundabout on the A1 then take a
look about 1/2 mile north on the left/ There is a field absolutely full
of ragwort, it also has 3 horses grazing in it. Totally crazy. Maybe
worth an email and photo to Defra.
--
Bill

Its ok so long as ragwort is growing as horses avoid it, the problems occur
when a field is made into hay as once dried they seem not to notice it. but
I would have thought it irresponsible to make hay from a field containing
ragwort (its not exactly difficult to spot) and its a lost cause down here

I suspect that it's actually illegal to make (or at least sell) hay
with ragwort in it.

--
Chris Green

In uk.rec.gardening Francis Burton wrote:
In article ,
Nick Maclaren wrote:
| Horses do indeed avoid eating live ragwort because the alkaloids
| make it bitter, but they may start to eat small quantities if the
| rest of the grazing is poor. They may even pick at it when there
| is grass available - I have seen that happen. So horses shouldn't
| be in fields containing ragwort (or vice versa), otherwise they
| could become poisoned.

Or perhaps they shouldn't be kept in the same field until there is
nothing else to eat?

I agree, it's bad management.

As has been repeatedly pointed out, picking at
ragwort will not poison them - it's only making it a primary part of
their diet.

Do you have a cite for that? What proportion of the diet would have
to be ragwort to make it "a primary part"? My understanding is that
a diet containing only 5% of ragwort is toxic, and that clinical
signs are evident at 10%.

It's nothing to do with the percentage is it? It's the absolute total
consumed long term, the effect is cumulative and irreversible.

I.e. if the fatal amount is (say) 10kg then the horse will die if it
eats 10kg in one year or if it eats 1kg per year for ten years. This
is my understanding of the way ragwort poisons livestock.

--
Chris Green

In article ,
writes:
|
| Do you have a cite for that? What proportion of the diet would have
| to be ragwort to make it "a primary part"? My understanding is that
| a diet containing only 5% of ragwort is toxic, and that clinical
| signs are evident at 10%.
|
| It's nothing to do with the percentage is it? It's the absolute total
| consumed long term, the effect is cumulative and irreversible.
|
| I.e. if the fatal amount is (say) 10kg then the horse will die if it
| eats 10kg in one year or if it eats 1kg per year for ten years. This
| is my understanding of the way ragwort poisons livestock.

That's unclear, and doubtful in the absolute way that you put it.
Animals have adapted to eating small amounts of common plant toxins
for long periods, and ragwort toxin belongs to a very common class.
It is quite likely that irreversible liver damage occurs only above
a certain rate of intake.

Whether that rate is very low or very high, I don't know. The fact
that the anti-ragwort camp assumes that it is very low proves nothing.


Regards,
Nick Maclaren.

In article ,
wrote:
Do you have a cite for that? What proportion of the diet would have
to be ragwort to make it "a primary part"? My understanding is that
a diet containing only 5% of ragwort is toxic, and that clinical
signs are evident at 10%.

It's nothing to do with the percentage is it? It's the absolute total
consumed long term, the effect is cumulative and irreversible.

I.e. if the fatal amount is (say) 10kg then the horse will die if it
eats 10kg in one year or if it eats 1kg per year for ten years. This
is my understanding of the way ragwort poisons livestock.

That is how I thought it worked too. There may, however, be a
threshold ingestion rate below which the alkaloids are fully
metabolized/excreted and no liver damage occurs. I just don't
know what that threshold is. As far as liver damage goes, it
is my understanding that it is effectively irreversible, i.e.
after ragwort poisoning the liver does NOT slowly recover
function. If that's true, horse owners' concern is entirely
justified imho.

Francis

On Aug 12, 5:27 pm, (Nick Maclaren) wrote:
In article ,tinn.. writes:

|
| Do you have a cite for that? What proportion of the diet would have
| to beragwortto make it "a primary part"? My understanding is that
| a diet containing only 5% ofragwortis toxic, and that clinical
| signs are evident at 10%.
|
| It's nothing to do with the percentage is it? It's the absolute total
| consumed long term, the effect is cumulative and irreversible.
|
| I.e. if the fatal amount is (say) 10kg then the horse will die if it
| eats 10kg in one year or if it eats 1kg per year for ten years. This
| is my understanding of the wayragwortpoisons livestock.

That's unclear, and doubtful in the absolute way that you put it.
Animals have adapted to eating small amounts of common plant toxins
for long periods, andragworttoxin belongs to a very common class.
It is quite likely that irreversible liver damage occurs only above
a certain rate of intake.

Whether that rate is very low or very high, I don't know. The fact
that the anti-ragwortcamp assumes that it is very low proves nothing.

Regards,
Nick Maclaren.

Yes from the research I have read that it indeed the case. There are
quite a number of steps involved before any harm is done at each point
there is a potential for the individual molecules to be rendered
harmless.

Neil Jones

In article . com,
wrote:
Yes from the research I have read that it indeed the case. There are
quite a number of steps involved before any harm is done at each point
there is a potential for the individual molecules to be rendered
harmless.

This principle surely applies to many molecular toxins. The
question is what is the safe ingestion rate for ragwort?

Francis

In article ,
(Francis Burton) writes:
| In article . com,
| wrote:
| Yes from the research I have read that it indeed the case. There are
| quite a number of steps involved before any harm is done at each point
| there is a potential for the individual molecules to be rendered
| harmless.
|
| This principle surely applies to many molecular toxins. The
| question is what is the safe ingestion rate for ragwort?

It does and it is. And I don't have a clue.


Regards,
Nick Maclaren.