Q: Is it enough to just give my horse a salt block or lick?
A: Many people rely on salt blocks to supply their horse’s daily salt requirements. However, while some horses have a craving for sodium, which will cause them to use a block, few horses lick a block enough to consume their daily salt requirement.
Of the five main electrolytes (calcium, potassium, sodium, magnesium and chloride), sodium, chloride, and potassium are the three most important, with sodium often considered the principal one as it’s the main regulator of thirst. When sodium and chloride combine, they produce sodium chloride. Sodium chloride is more commonly known as salt. It thus makes sense to add salt to the horse’s daily diet to provide two of the most important electrolytes, sodium and chloride.
A 500kg horse, in no work at cool temperatures, has a daily requirement of 10 grams of sodium and 40 grams of chloride (NRC, 2007). However, a 500kg horse in medium work has a requirement of 17.8 grams and 53.3 grams, respectively, and this does not allow for any work in high temperatures, such as those we experience here in South Africa. To give some idea, a 500kg horse in no work, at cool temperatures, would need to consume a 1kg block of salt per month to consume their daily maintenance requirements. They would need even more if they worked hard and in hot temperatures.
If your horse is consuming 1kg of salt in the form of a salt block per month and doesn’t work, you are absolutely fine to keep providing a salt block as a sole source of sodium and chloride. However, for those with higher daily requirements, or where the horse tends to consume less salt than is necessary from a salt block, it’s worthwhile to provide 15 grams (1 tablespoon) per 250 kg of body weight to their ration every day as a minimum. In the case of a 500kg horse, this would equate to 30g per day, so around two tablespoons of salt. Feeding it with the ration, rather than relying on your horse to ingest it ad-lib, ensures your horse is receiving the correct amounts to perform at his best.
Some horses appear to prefer sea salt or Himalayan salt over regular table salt (avoid Lite salt as this usually is potassium chloride and will not assist in maintaining sodium levels). At this time, there is no research on horses to indicate any nutritional benefit of these forms of salt. However, if your horse prefers these forms, then they will be worthwhile as the horse will be more inclined to eat/lick something he enjoys.