Requirement for sodium (Na) or common salt (NaCl) varies greatly according to the temperature and the working intensity of the horse.
PC-Horse estimates the requirements during winter (October - April) to be 60% of summer requirements.
Breeding mares and growing horses should always have access to a salt or mineral lick with a high salt content.
Horses which are trained or exercised heavily may have problems with regulation of salt intake. Such animals should therefore be given a controlled amount of salt every day.
Recommended amounts of salt for horses which are trained are 5-6 gram per 100 kg body weight in winter, and 6-10 gram during summer, when they sweat more.