252 Assessment of Modern Gilts and Sows Body Weight Throughout Gestation and How Different Daily Energy Intakes Meet the Energy Requirement for Maintenance at Each Parity

Abstract Growth and efficiency of modern maternal lines have improved over the years. Our hypothesis is that modern sows are larger and heavier, and, consequently, have increased energy requirements for maintenance (MEm). Two datasets were used to estimate gilt and sow body weight (BW): 1)1,903 PIC Camborough gilts were weighed at breeding and at d112 of each gestation from parity 0-3; 2)1,150 PIC Camborough gilts and sows (ranging from parity 0-12) were weighed at d4 and d112 of one gestation (Thomas et al., 2018). Average BW between breeding and d 4 of gestation were 154, 185, 213, 232, 225, 231, 236, and 247kg for parities 0, 1, 2, 3, 4, 5, 6, and 7+, respectively. Growth of females throughout each stage of gestation was estimated assuming that 30% of the BW gain occurred until d 60, and 70% from d 61-112. The MEm was calculated according to NRC (2012) model. Different feeding levels were simulated to estimate the percentage of MEm that they would achieve if fed throughout gestation: Level1) 5.17 or 3.85 Mcal of ME or NE/d; Level2) 5.90 or 4.40 Mcal of ME or NE/d; Level3) 6.46 or 4.82 Mcal of ME or NE/d. Feeding Level1 would result in gilts fed below maintenance from d 90-112 (Figure1), parity1 sows fed below maintenance from d 30-112, and parity2+ sows fed below maintenance throughout the entire gestation. Feeding Level2 would result in a few gilts, half parity1, and all parity2+ sows fed below maintenance from d 90-112. Feeding Level3 would result in all gilts and parity1 sows fed above maintenance throughout gestation, and a quarter of parity2+ sows fed below maintenance from d 90-112 of gestation. In summary, due to heavy body weights and high MEm requirement of modern sows, there is a need to re-evaluate the implications and trade-offs between feeding levels and reproductive performance.