The answer to the question ‘Should I be adding salt to my horse’s diet and how much”, does depend somewhat on what your horse is doing, current feed and intakes, workload, season and climatic conditions.
A 500kg horse at maintenance has a Sodium requirement of approximately 10g and a Chloride requirement of 40grams daily (NRC, 2007). A 500kg horse undertaking a moderate workload will have a Sodium requirement of approximately 18grams and a Chloride requirement of 53grams (NRC, 2007). It is important to note that a warmer climate and an individual’s freeness to sweat and varying intensity of their work will further influence sweat loss and therefore Sodium and Chloride requirement.
Forages are generally recognised for being a poor source of Sodium.
Premixed feeds have Salt added and if being fed at the recommended intakes, these feeds will in many situations meet the Sodium and Chloride requirements for a horse at maintenance in a cooler climate. However, as indicated above for horses that are sweating daily, further salt (Sodium and Chloride) supplementation is recommended. Higher intakes for those that do not receive salt from other forms of supplementary feed may be required.
Salt licks provided in the paddock allowing the horse free access to salt is good idea. However, for horses that are working and sweating daily, this should not be relied on as the only source of Sodium and Chloride. Adding some plain salt to the feed will assist in ensuring that your horse’s requirements are being met. The amount added will depend on the other feed stuffs in the diet and the individual’s daily sweat loss.
Salt should be supplemented daily - the amount depending on how much the horse sweats, with higher intakes on heavier sweat days. When feeding a premixed feed at the recommended intake, salt supplementation may vary from 10-60grams per day.