Thursday, 2 January 2020

Horse nutrition bible ragwort nonsense.

As it is the new year I have been doing something which I do every few months.
I scour the internet and various sources and archives for information relating to ragwort.

This is a useful activity to do, as quite frequently new things appear. Often  they are really old things which somehow have been put on-line or archived somewhere or other. This happened last year when I found out about the old article by Professor Derek Knottenbelt. I have just updated my article on it again. This time I number the problem issues in it in my debunking on my website. There are SEVENTEEN of them.

If we had only had this kind of information back in 2004 we could have really stopped a lot of the hysteria, because we would have been able to establish very clearly that the information being circulated was nonsense.

In the process of doing this searching process for this new year. I came across some text from a book. It is called The Horse Nutrition Bible : The Comprehensive Guide to the Feeding of Your Horse and it was published in 2003.

It contains the following text, which I will deal with piece by piece.:-
Of the many plants poisonous to horses, the one they are most likely to consume is ragwort.
Do we really know this? Is it provable? I don't know of anything in the scientific literature that substantiates it.

This and other toxicants, such as heavy metals and some mycotoxins, can cause liver damage.
This is true. Indeed, the damage done by the breakdown products of the compounds in ragwort, that actually produce the toxic effect, cannot be distinguished  from damage done by mycotoxins. They produce the same damage on a molecular level, by cross linking DNA molecules.

Then there is this well-known falsehood.

 In the case of ragwort poisoning, the poisonous principle,
pyrrolizidine alkaloids, accumulates in the
liver and halts its regeneration. 
Oh no it doesn't!  The alkaloids do not accumulate, indeed they are destroyed in the process of cause toxicity, as I say above!  The damage indeed can be cumulative, but there are repair mechanisms and small doses will not cause problems.  We know this from the biochemistry and is an important difference.
If it were to accumulate then every bit would count. With damage accumulating every bit isn't important, because the repair mechanisms prevent damage for small doses. This text in this "Bible" exaggerates the risk.

Incidentally, I blogged recently about people believing that civil servants and government departments were infallible. This error was also made by Scottish civil servants in an official publication some years ago.

And here we go again, another false claim.

Liver disease is becoming increasingly common,
mostly due to the rapid increase in the
amount of ragwort in and around horse
pastures in Britain.
As I point out in the debunking of the Knottenbelt article which I link to above. there was a survey of plants done by the government that covered this period. It showed that ragwort had decreased at this time.

This is yet another example of a horse textbook with poor information on ragwort.

Finally as it is the new year I will once again post the video of the current lead expert in the UK Professor Andy Durham. He has actually done research. Here are some quotes Ragwort poisoning is  "pretty rare really" "I do think we
need to stop talking about it so much." ,  "In reality there really is no evidence it's a common cause of liver disease  in horses."
It is an audio only video of the relevant part of a longer podcast with a small segment added to explain a point which he made at a  meeting that a colleague attended explained with reference to other experts' writing. It lasts just 1 minute 48 seconds in total. Listen to it!

Oh and just in case some ragwort basher tries to say I am taking things out of context, here is the original podcast which lasts 33 minutes.

The video below is shorter but contains the relevant piece.

Ragwort Hysteria latest entries

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