You do your horse a favor if you examine the content of any salt block before buying it. Your horse needs both salt and minerals; “trace minerals” refer to minerals your horse typically needs less than other minerals. The necessary mineral balance may also depend on what minerals it gets from hits other nutritional sources, so your best option is to examine your horse’s entire diet and supplement only as required. The typical trace mineral salt block is primarily composed of salt.
According to the ADM Alliance Nutrition Equine website, a 1,200-pound house gets approximately 73.5 percent of its salt requirement from a typical commercial equine salt and trace mineral block. Most horse grains are typically low in salt, so providing it free-choice both in his turn-out area or stall, if it has one, is ideal; your horse is likely to self-regulate its salt intake according to its needs. Some horse owners prefer to give loose salt versus block, as a horse’s tongue is not rough and it may have a harder time licking as much as it needs from a block. Loose salt can also be top-dressed on your horse’s grain; about 1 to 2 oz. daily should be adequate for most horses.
Your horse needs some minerals more than others to be healthy; these are referred to as “macro-minerals.” Macro-minerals are calcium, phosphorus, magnesium, potassium, sodium and chloride. Your typical equine trace mineral salt block provides zero to negligible amounts of these essential macro-minerals. If your horse does not get them from some other source, such as grain, you may notice serious health deficiencies.
As the name implies, horses require very little trace minerals, or micro-minerals. These include copper, cobalt, iodine, iron, manganese, selenium and zinc, all of which are commonly found in your salt and trace mineral blocks. Your horse’s selenium needs are typically met through regular intake from the salt and trace mineral block, as well as much of its iodine requirements. You should monitor the frequency with which your horse licks its mineral block to help assess whether its needs are being met.
Signs of Mineral Deficiencies
Monitoring your horse’s behavior, as well as its overall appearance, can help you catch signs of mineral deficiencies. For example; you might suspect a phosphorus deficiency if your horse's coat is dull and lifeless, or if it starts eating dirt or wood. Excessive nervousness or “spook” can be an indication that your horse’s diet is not fulfilling the magnesium requirements. Supplementing these important minerals or adding a mineral-enriched grain should lead to a noticeable improvement in your horse's overall health.