Fifty-five first lactation sows were used to evaluate how the dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratio affected nitrogen use by the sow and piglet growth performance. Sows were randomly assigned to one of five diets that had equally spaced and increasing SID Lys-to-NE ratios from 2.85 and 5.51 g SID Lys/Mcal NE that were fed for a 24-d lactation. The ratio of SID Lys-to-NE did not affect sow feed intake, milk nitrogen output or piglet growth during any week of lactation. Sows that were fed increasing SID Lys-to-NE ratios lost less body weight and back fat during lactation. The SID Lys-to-NE ratios of 4.74 and 4.85 g SID Lys/Mcal NE optimized maternal nitrogen retention in weeks two and three of lactation, respectively, but a ratio greater than 5.51 g SID Lys/Mcal NE was necessary to minimize maternal nitrogen losses in week one of lactation. Therefore, using optimal SID Lys-to-NE ratios in each week of lactation could improve nitrogen retention in the maternal body for sows in the first lactation, but with minimal effects on piglet performance.

Read the full article in the Journal of Animal Science.