White salt blocks are a popular way of providing horses and livestock with extra salt. Like pink salt (Himalayan and Redmond Rock etc.), white salt is primarily composed of sodium chloride.
Compressed white salt blocks come in a variety of sizes, with a popular size in the US being 50 pounds (22.7 kg.).
Sodium is important for hydration. A large horse requires approximately 28 grams (2 US tablespoons) of sodium chloride a day. Other animals such as poultry, goats, pigs etc.. have varying mineral requirements depending on their age, size and stage of production.
Salt products are typically available either with, or without, iodine. Iodized salt contains iodine. Iodine deficiencies can lead to an enlargement of the thyroid gland (goiter), a condition which is most often found in young animals.