Mineral nutrition of the sow: a review.

The sow varies greatly in her mineral requirements, which largely reflects the nutritional demands during different phases of her reproductive cycle. Minerals are required for conceptus product formation, mammary secretions, and growth and maintenance. Although the sow's mineral requirements are highest during late gestation and lactation, those that are supplied from the diet and tissue reserves both contribute in meeting these nutritional needs. The sow is fairly resilient to borderline mineral insults, but longevity in the herd may be compromised under these conditions. Specific mineral deficiencies vary, but the reproducing sow will deplete the pool of tissue minerals before litter size, congenital abnormalities of developing fetuses or milk mineral composition are affected. Inadequate mineral supplies may prolong the duration of parturition, increase the number of stillbirths and result in a higher occurrence of skeletal problems. Tissue mineral reserves can be increased in various tissues with higher dietary fortification, but subsequent mineral availability from various pools differ. Because feed intake during lactation is low, daily mineral intake during lactation often is below NRC (1988) requirements.