Effects of feeding levels on ileal amino acid digestibility of extruded full fat soybeans in nongestating sows

The objectives of this study were to investigate the effect of feeding levels on amino acid (AA) digestibility of extruded full fat soybeans (EFSB) fed to nongestating sows and to provide a reference for setting feed intake level when evaluating the quality of nutrients in the feed ingested by sows. Twelve nongestating sows (parity 3 to 5) were fitted with a T-cannula at the distal ileum. After recovery, sows were assigned to a replicated 6 × 3 incomplete Latin square design using two diets (nitrogen-free and EFSB) and three levels of feed intake (1.3, 2.0, and 3.4 times the maintenance requirement for metabolizable energy (ME)). The design included six dietary treatments and three periods, and each period contained two replicates for a total of six replicate sows per treatment. All diets contained 0.3% chromic oxide as an indigestible marker. In each period, ileal digesta samples were collected continuously for 12 h on days 6 and 7 after 5 d of acclimation to the experimental diet. Results of the experiment indicated that different feeding levels (1.3, 2.0, and 3.4 times the maintenance requirement for ME) had no effects on apparent ileal digestibility (AID) of AA and standardized ileal digestibility (SID) of AA, but feeding level did affect the endogenous AA loss estimated using the nitrogen-free diet method. Endogenous phenylalanine excretion was greater with 1.3 times than with 3.4 times the maintenance requirement for ME (P = 0.03), and endogenous tyrosine excretion was greater with 1.3 and 2.0 times than with 3.4 times the maintenance requirement for ME (P = 0.01). Increasing feed consumption resulted in greater loss of total endogenous AAs and crude protein (CP). In conclusion, feeding levels of 1.3 to 3.4 times the maintenance requirement for ME did not affect the AID and SID of AA of EFSB fed to nongestating sows.

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

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.