Sodium and chlorine
Sodium and chlorine are involved in nutrient absorption, electrolyte balance, and regulation of pH. Salt or sodium chloride (NaCl) is the most common source of sodium and chlorine, composed of approximately 40% sodium and 60% chlorine. The supplementation of diets with salt is essential because sodium and chlorine are low in grains and oilseeds. However, dietary supplementation of salt is usually reduced in diets with co-products from the food industry, spray-dried whey, or spray-dried blood products due to the high concentration of sodium and chlorine in these ingredients.
The requirements for sodium and chlorine are greater for nursery pigs and abruptly decrease for grow-finish pigs and sows (NRC, 2012). Thus, meeting the requirements for sodium and chlorine is particularly important for nursery pigs (Shawk et al., 2018) (link to NP5 Minerals in Nursery Diets fact sheet). Diets deficient in salt result in decreased growth performance because of reduced feed intake and poor feed efficiency. Diets with high levels of salt are generally well tolerated if drinking water is available. However, if drinking water is restricted, toxicity can quickly occur.