Welcome to the Beef and Dairy Network website, the number one website for those involved or just interested in the production of beef animals and dairy herds. The Beef and Dairy Network website is the website companion to the Beef and Dairy Network Podcast and printed magazine, brought to you by Granium Nutritional Sand. Today, we have an interview with Doctor Margaret Lodestone, a bovine magnet vet from Yorkshire.
A lot of people are not aware that cows are magnetic. Can you explain why cows are the only known animal to have this property?
Well, it's an evolutionary adaptation. Cows, majestic as they are, swallow large amounts of material without chewing it at all, because they then spend large amounts of time regurgitating it and chewing it. They aim for grass, of course, but this can include things like barbed wire and other metal that may be in the field with them. Right up until the 1950s, cows regularly died from a disease they contracted as a result: hardware disease. The metal would, having settled into their second stomach, pierce the cow's organs and cause all sorts of bother. Sometimes, particularly if the cow gave birth, the metal would pierce the actual heart muscle and kill the cow.
In the 1950s, however, the beef and dairy industry began to see an astounding change: cows began to develop magnets inside their rumen. At first the magnets were too small to make a significant difference in the disease rate, but slowly through the 1960s and 70s we would slaughter cows and discover larger and larger magnets inside their stomachs, often surrounded by all the metal they had collected throughout the cow's life.
So are cows still evolving to become progressively more magnetic?
It's hard to say, of course, as evolution is a slow process, but we think not. The magnets are now about the size and shape of a human finger, and it's enough to effectively prevent hardware disease about 95% of the time.
Is this true for all cows in Britain? All across the world?
It is true for all cows in Britain, certainly. If you have a cow born without a magnet -- you check by using a compass, generally -- then you can either let nature have its way and leave the cow to tragic and painful suffering, or you can insert an artificial magnet, much in the same way we would artificially create arses in cows born arseless. These artificial magnets are somewhat less effective, however, and no one is certain why. It could be that part of the naturally-occurring magnet involves magnetic nutrients from the mother cow.
In terms of worldwide cattle populations, we've only seen this adaptation in countries that do have significant amounts of metal in pastures. Once it was discovered as an adaptation in Britain, British metallic studs were sent all over the world so that other countries could benefit, so you see the British metallic line across Europe.
As a magnet vet, what do you focus on in your work?
I advise farmers on the best artificial magnets available to them, and I also get called out when a cow suddenly gets de-magnetised. This can happen if cows gets too enthusiastic in their displays of affection for other cows -- the two magnets can throw each other off. Generally, at that point we have to add an additional magnet, because the standard ways of increasing the strength of magnets just aren't available -- hammering the cow is not really ideal until after it's been to the abattoir, and while we could apply an exceptionally strong magnet to force the natural magnet to realign, that also runs the risk of puncturing the cow.
So what you're saying is that you should never have your wallet in your pocket while checking on your herd?
Absolutely not, and most farms now have signs saying the farmers are not personally responsible for any information loss that may occur as a result of technology being affected by magnetic cows. The Bovine Farmers’ Union has ensured that is absolutely watertight in terms of legal issues.
That's all for this week, tune in next week when we speak to Nadiya Ahmed, the choreographer for the National Cow Ballet.