Too Much Salt Might Be Killing Gut Bacteria

The last two weeks has seen extreme weather conditions for us in my local area in Australia. In the last 14 days, 7 days have been 40 degrees celsius or higher (104 F +) and of the other 7 days only one was below 37 degrees C (99 F). To make things worse, the nights will not cool down, with most nights remaining over 20 degrees C (68 F) and a couple of nights being 26 + degrees C (79 F). On more than one occasion I have checked temperatures between midnight and 3 am and it has been 30 degrees or more in the middle of the night! It is HOT!!!

My horses are crusted in salt from continuous sweating. I took pity on them today and instead of having them out grazing with muzzles on they have hay in their hay pillows so they can at least stay in the shade.

But back to salt. I normally just let my horses eat salt free choice. Their balancer pellet gives them about 5 grams of salt per day and the rest of what they need they eat as loose rock salt.

BUT, the last couple of weeks I have been adding it to their feeds so I know they are getting enough to keep sweating. If horses run low on sodium or chloride they can’t sweat, and that, in these conditions is life-threateningly dangerous.

There is a trend at the moment though for people to add large amounts of salt to their horse’s daily feeds, despite actual requirements or what may be coming from the rest of their diet. Blanket recommendations like ‘add 10 grams of salt per 100 kg of bodyweight’ seem to be commonplace, yet don’t seem to take into account a horse’s specific situation.

Take Poet’s diet for example, shown in the graph below. If I add 10 g/100 kg of BW to his diet his sodium intake is well over 200% of what he needs. In these extreme conditions this may well be accurate, but once it cools off a little this is way more sodium than he needs.

While I was out just now giving them hay I had the thought ‘I wonder what this excessive salt might be doing to the bacteria in their gut’?? Salt is, after all one of the best known and most widely used anti-bacterial agents in the world.

So I did a little research… and while not much came up, there is a recent paper, published in ‘Nature’ (i.e. one of the most reputable journals in the world, so we can trust it) showing that in both mice and men adding more salt than normal to a diet affected the gut bacterial populations, in some cases it entirely wiped out certain strains of bacteria! Eek!

What is really interesting (from a human perspective) is that the researchers were then able to link those shifts in gut bacteria to high blood pressure, which may help to explain (the as yet poorly understood) link between high salt diets and hypertension.

Back to your horses though… feeding excessive salt is unlikely to have any benefit and may be negatively affecting the good bacteria in your horse’s gut. So when using FeedXL, just meet your horse’s requirement for sodium with salt that is added to the diet. Then leave free choice salt (preferably as easy to eat loose rock salt) out so they can top up any extra requirement they may have.

The paper is here if anyone would like to read it in more detail: https://www.nature.com/articles/nature24628

Questions? Comments?

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