Improvements in modern sow prolificacy have markedly increased the number of pigs weaned, thus the ability of sows to provide nutrients to support fetal growth and milk production has been enhanced. The goals of the gestation nutrition program consist of meeting the nutrient requirements for maintenance and growth and for adequate conceptus development, while managing body condition. Early gestation represents the best opportunity for replenishing body reserves, whereas in late gestation, both estimated protein deposition and energy requirement are exponentially increased and directed towards fetal growth and mammary development. Increased feed intake after breeding has been presumed to be detrimental to embryo survival; however, data with modern line sows demonstrates to feed thin sows to recover body condition as quickly as possible while avoiding feed deprivation immediately after breeding. Importance of body condition scoring remains unchanged: feed thin sows to bring back to adequate body condition and prevent over-conditioned sows at farrowing.
A recent meta-analysis showed increasing late gestation feed intake seems to modestly improve piglet birth weight by 28 g per piglet in gilts and sows. Also, recent findings in gestating sows suggest modern genotypes have improved feed efficiency and propensity for growth. Therefore, increasing energy intake during late gestation has a modest effect on piglet birth weight and a negative effect on stillborn rate. Historically, lactation catabolism impacted subsequent reproductive performance of sows, particularly in first-parity. However, contemporary sows appear to be increasingly resistant to the negative effects of lactational catabolism. Even so, continued emphasis on maximizing lactation feed intake is critical to support milk production and prevent excessive lean tissue mobilization. Research data suggests that ad libitum feeding and offering lactation diets during the wean-to-estrus interval is not needed.
Modern genetic sow lines appear to be more robust from a nutritional perspective than in the past.