Precision feeding in gestating sows: a retrospective analysis of lysine intake and pregnancy outcomes

Abstract

From day 30 of gestation, 288 mixed parity sows were fed a diet varying in the inclusion of lysine and other amino acids, to meet changing requirements throughout gestation more closely (precision feeding). Lysine inclusion for precision fed sows was varied by parity group and was altered every few days by blending two diets differing in lysine at varying ratios. As a reference, 280 mixed parity sows were fed a single gestation diet consistent in lysine and well above requirements (NRC 2012). To investigate the role of lysine intake in prenatal development, standardised ileal digestible (SID) lysine requirements were estimated retrospectively based on realised maternal gain and litter weights at farrowing. SID Lysine excess was calculated over day 30 to 80 of gestation, the period of accelerated placenta growth, and defined as lysine intake minus requirements. SID Lysine excess was lower for precision fed sows, and sows with lowest lysine excess (1 g/d or less) had lower foetal survival (90.8 % vs 93 to 95 %), more mummies per litter (0.6 vs 0.2 to 0.3), and more litters with at least one mummy (38 % vs 12 to 21 %), compared to sows with SID lysine excess of 1 g/d and more. In conclusion, when feeding amino acids closer to requirements, in some sows this may result in feeding under requirements, potentially compromising foetal development. This study provides a previously undefined safety margin for SID lysine of 1.5 g/d, which can be used to formulate gestation diets and feeding strategies.