Ideal Salt Levels for Horses ExaminedBy Kentucky Equine Research Staff · January 25, 2017
Equine nutritionists recommend offering supplemental salt (sodium chloride, NaCl) to all horses because typical forages and feeds contain low levels. According to nutritionists, the “salt theory” holds especially true for exercising horses that lose valuable electrolytes in sweat. A recent review of the literature, however, questions traditional views on salt supplementation, suggesting that just a dab will do.
The reviewers indicate that even horses supplemented with inadequate or no supplemental salt maintained good performance and undisturbed health. They hypothesized that horses naturally adapt to low salt levels by decreasing excretion from their kidneys and hindgut.
To test these assumptions, the researchers looked at moderately exercised Warmblood mares on a low-forage diet with increasing levels of daily salt supplementation, up to 100 g/day. While the highest level of salt supplementation appeared to have an acidifying effect on blood and increased sodium and chloride excretion in the urine, the moderate level (50g/d) and no supplemental salt did not.
Keep in mind this research was done with low to moderate ambient temperatures with no question of heat stress.
In contrast, other experts, including Kathleen Crandell, Ph.D., a nutritionist with Kentucky Equine Research (KER), maintain that salt supplementation benefits horses for the following reasons:
- Equine sweat is rich in sodium and chloride, and diets with limited salt, like most unsupplemented equine diets, may cause disturbances of fluid and mineral balances when a horse is losing electrolytes with heavy sweating;
- A horse’s voluntarily intake of supplemental salt ranges between 0 and 62 mg salt/kg body weight daily, which is less than the currently recommended intake by Nutrient Requirements of Horses of 100 mg/kg body weight daily for a horse at maintenance, but shows an innate need for salt in many horses; and
- Horses offered plentiful forage can reduce or even eliminate the potential acidifying effect of supplementary salt, thereby negating concerns about metabolic acidosis seen in this study with low forage intakes.
“It is not time to throw away the salt block, especially for horses that are exercising for extended periods of time or in hot environments. If horses are not offered free-choice salt, they frequently seek it out in other places like soil or treated wood used in fencing. In sum, offering free-choice salt seems like a better alternative,” concluded Crandell.
*Zeyner, A., K. Romanowski, A. Vernunft, et al. 2017. Effects of different oral doses of sodium chloride on the basal acid-base and mineral status of exercising horses fed low amounts of hay. PLoS One. 12(1):e0168325.