How Should I Feed My Horse Salt? Part 1

I've been wondering about this topic for some time myself, so I decided to do some research.

The basic premise is that sodium and chloride (the building blocks of NaCl, salt) are essential to a horse's diet. This article on minerals from The Horse suggests that a horse in no work should be receiving 0.25% of its diet as salt, and a horse in full work, sweating regularly, should receive closer to 0.75% of its diet as salt.
So, let's do the math: a horse should consume 2% of its body weight per day; for a normal 1,000 lb horse, that's about 20 lbs a day. 0.25% of 20 lbs is 0.8 ounces, or approximately one tablespoon of salt. 0.75% of 20lbs is 2.4 ounces, or approximately 1/4 cup of salt. So if you have a draft horse in the summer in regular work, your horse might need as much as 1/2 cup of salt a day!

It's tough for horses to overeat salt, especially if they have access to water - excess minerals will just pass through with urine. It is possible, though, for horses who drink briny water (in the absence of fresh, clean water) or flat-out eat a salt block. Symptoms include colic, diarrhea, and weakness of the limbs. Most people believe that horses will self-regulate, eating as much salt as their bodies need. Some horses may lick dirt or rocks, or eat the roots of plants and grass, in order to get at extra minerals when their bodies are lacking them.

(For fun again, here's the math. A lethal dose of salt for horses is considered 2.2g/kg. That works out to 2.2 lbs, or a little more than 3 1/2 cups of salt. Your horse would basically have to eat most of a 3lb salt block in a short time period.)

Horses get salt through their regular food intake: processed grain, hay, and grass. Most of the time, though, these food sources don't add up to enough, especially if the horse is in any kind of work and sweating. Salt is a key part of the electrolyte balance that allows a horse to function - see this article, again from The Horse, for a fairly long and complicated explanation of the role electrolytes play in equine biology. (You can do a quick Google or take a look at your grain bag label to see how much salt is in the grain, and you can almost always send your hay out to be tested for the same information, if you really want to get down into the weeds for this information.)

In short, you almost always need to supplement salt in your horse's diet. But how do you do that? Here are the most common ways, with their pros and cons.

Loose Salt

Exactly what it sounds like: loose salt, added to your horse's feed. You can add this in a couple of ways. Some people dress grain with it, much like a supplement, a tablespoon or two at a time. Some people leave out a bucket of loose salt for the horse to eat as it chooses.

Pros: Easiest to eat, practically guarantees a daily salt intake, doesn't take up room in a horses's stall or field

Cons: Salt might turn some horses off grain, overeager horses will eat too much, must be fed in a stall, could get expensive, might get skipped if you're boarding (like any other supplement)

I found argument both ways about exactly what type of loose salt to use: iodized salt for people? loose bagged salt for livestock? something in-between? No really clear answer here.

Salt Blocks: White

These blocks come in various sizes, from the small 3lb ones that you put on a wall to the large 50lb block that's pictured here. 

Pros: Inexpensive (usually $3-5 for the 3lb blocks and $10-15 fot the 50lb blocks), last a long time, can really take a beating, provide an entertainment value alongside nutrition

Cons: There is a school of thought that believes these blocks are meant for cattle, and a horse's smoother tongue cannot lick long and hard enough to get enough salt off the block. This school of thought argues that horses often resort to biting the blocks, which can cause TMJ and other jaw irritation and then lead to breaking off large, unhealthy chunks that can cause salt poisoning. They also take up space in a stall, whether on the wall or on the floor.

Salt Blocks: Trace Minerals

This is a fairly wide category; if you search at Tractor Supply on "salt block" you'll return a few dozen variations with different trace minerals. I've put up photos of the two most common here. On the left, a salt block with added sulfur; on the right, one with added iron. You have to look at the ingredients list for precisely what proportions of what minerals are represented. Each color typically reflects a different mineral composition. For the sulfur and iron blocks, they're about 95-97% salt and 3-5% other mineral.

Pros: Much the same as a plain salt block, these are inexpensive (maybe a dollar or two more than plain salt), durable, and slow a horse's consumption down

Cons: Same as above; are these really meant for cattle?

There is an interesting additional con to consider, however, and it's this one that sent me on my original research quest. Are the added minerals bad for horses? I did quite a lot of reading, and the most reputable sources pointed out that these are still mostly just salt, and that a horse would really have to consume a LOT in one day to reach any kind of overload on the minerals. That said: there are some that really should not be eaten by horses, so avoid anything that's specifically formulated for other animals like sheep or goats. (There are some minerals that can be overconsumed, selenium being the first among these.)

Some anecdotal reports suggest that feeding the sulfur blocks can be a sort of natural fly repellent, much like apple cider vinegar. There's no scientific evidence to support this. Sulfur is a necessary component of a horse's diet, but a tiny one, and they pretty much get what they need from their regular feed.

Horse-Specific Mineral Blocks

The variations in this category are endless. You've definitely seen these, and they are often marketed with various flavors as "treats." These provide quite a lot more in the way of basic minerals and nutrients.

For example, here's the nutritional analysis for the Dumor Horse Block:

Crude Protein (min.) 16.00%, Lysine (min.).60%, Crude Fat (min.) 2.00%, Crude Fiber (max.) 10.00%, Calcium(Ca)(min.) 1.50%, Calcium(Ca) (Max) 2.00%, Phosphorus(P) (min.) .60%, Salt(NaCl) (min.) 10.00%, Salt(NaCl) (max.) 12.00%, Sodium(Na)(min.) 5.00%, Sodium(Na) (max.)6.00%, Copper(Cu) (min.) 55.00ppm, Selenium(Se) (min.) .60ppm, Selenium(Se) (max.) .70ppm, Zinc(Zn) (min.) 150.00ppm, Vitamin A (min.) 10,000IU/lb, Vitamin D(3) (min.) 2500IU/lb, Vitamin E (min.) 250IU/lb, Animal protein products-free.

That's a LOT more stuff than is in any of the other salt blocks!

Now take a look at the ingredients for that same block:

Wheat Middlings, Cane Molasses, Salt, Dehydrated Alfalfa meal, Cottonseed meal, Ground Milo, Sunflower Meal, Calcium Carbonate, Bentonite, Ground Soybean Hulls, Rice Bran, Cracked Corn, Dehulled soybean Meal, Monocalcium Phosphate, Dicalcium Phosphate, L-lysine, Vitamin E Supplement, Copper Sulfate, Vitamin A supplement, Vitamin D3 Supplement, Ethylenediamine Dihydriodide, Manganous Oxide, Zinc Oxide, Calcium Iodate, Magnesium Oxide, Ferrous Sulfate, Mineral Oil, Sodium Selenite. 2.000% Ground Soybean Hulls.

See #2? Molasses.

Pros: These really are the only salt blocks that are 100% meant for horses. Horses love them. They do provide quite a lot of nutritional kick to them. If your horses are pastured 24/7, on range, or do not get any grain, these can be a great supplement.
Cons: Molasses! Any horse with sugar sensitivities should stay far away from these blocks. Many horses, in fact, will go after these until they are gone because they reward licking with great taste beyond just satisfying a salt craving. They're also not really salt blocks: only 10-12% in the Dumor block, as opposed to the 95%+ of a typical salt block. They are way more expensive than a plain salt block, easy 2-3x as much.

They also have a lot in them, most of which is supplied by processed grain. So if your horses is on any kind of grain, they probably don't need what's in these blocks. Note that many of these blocks also contain selenium, which is dangerous in large quantities.

Himalayan Salt

The newest and trendiest way to feed salt. What is "Himalayan" salt, exactly? Rock salt, or halite. Most of the pink stuff that's mined and marketed as Himalayan comes from Pakistan.

Here's a selection of claims about this salt: "it contains the full spectrum of 84 minerals and trace elements just like Mother Earth intended," "The Original® Himalayan Crystal Salt® is more than salt, it's a way of life -- or more precisely, a way of approaching aspects of living your life well," "a pure, hand-mined salt that is derived from ancient sea salt deposits, and it is believed to be the purest form of salt available."

Does anyone else have the same knee-jerk reaction to fads that I do? Sigh.

Himalayan salt does contain other trace minerals beyond just salt. What, exactly? We don't know. It depends. On a lot of things. It's really not clear whether any of them are beneficial or not. Certainly it's not analyzed before it's sent out to stores. So believe whatever you want about its human benefits, here's what it does for horses.

Pros: much harder than the processed salt blocks - can last much longer, often comes on a neat rope hanging thingy, your horses will look cooler and more loved than all his friends with his trendy pink salt lick

Cons: those extra trace minerals, super expensive, that same hardness might work against it (see above for arguments about effective salt intake)

Electrolyte Supplements

Last but not least: since we are feeding our horses salt primarily to aid in their water intake and exercise resources (here's that article again from The Horse for the technical stuff), you can also substitute or supplement your horse's salt consumption with electrolytes. (Here's a good recent thread from the Chronicle of the Horse forums about salt v. electrolytes.)

Electrolytes never contain just salt; at their most basic, they have sodium, potassium, chloride, calcium, magnesium. These are the basic minerals that help a horse to process heat & exercise and to sweat appropriately. There are endless variations in electrolyte supplements. Smartpak currently (August 2014) carries 15 different varieties, and interestingly enough, they list basic salt as one of them! 

In the reading I've done, here's the consensus: most horses do not need a daily electrolyte. If they're in average work, they'll replenish what they need from salt, hay, and grain. If they're in heavier work in the heat, they may need a general supplement on that day, one dose or so. Horses in intensive work, such as endurance rides, may need electrolyte supplementation during that work. Basically, if they're burning through it faster than average eating can replenish. It is, however, all too easy to overdose on electrolytes and cause a general system imbalance, so you shouldn't just pour them down your horse's throat. It's important to know and watch your own individual horse if you're doing high-exertion exercise. (And even then, you can get into trouble, unfortunately; horse sports are not without risk.)

The purpose of this blog post, though, is to consider ways to get salt into your horse, so with that objective in mind:

Pros: electrolytes provide a full-spectrum replacement alongside salt, which can be great
Cons: your horse probably doesn't need them, so this is NOT the main way you should plan on getting salt into his system; examine labels carefully to make sure that the minerals you need are there, and that it's not loaded with added sugar.

SO. Whew. If you've stuck with me through that, congratulations! Those are the basic ways to get salt into your horse's diet.

In Part 2, coming soon, I'll discuss what I have used in the past for Tristan and what I'm going to do going forward based on this research.