Effect of increasing lysine supply during last third of gestation on reproductive performance of Iberian sows

Ninety purebred Iberian (IB) sows in second or third parity were used to determine the effects of dietary lysine (Lys) concentration during last third of pregnancy on sow and litter performance. The sows were randomly assigned to one of three dietary treatments: 5.5 (LLys, Control), 7.4 (MLys) and 8.7 (HLys) g Lys kg-1 diet. Feed allowance was 2.30-2.33 kg d-1. Close to farrowing a conventional lactation diet was used. Dietary Lys did not affect body-weight (BW) gain in late gestation of second-parity sows. However, in third-parity sows, a strong tendency was observed for BW gain to increase during late pregnancy with dietary Lys levels higher than 5.5 g kg-1 (p=0.061). Body-weight losses during lactation were never influenced by Lys supply. A strong tendency (p=0.064) for a lower ratio between piglets born alive and total piglets born was observed in second-parity sows fed the Control gestation diet. Litters and piglets from sows on this diet had the lowest weight at birth (p0.05). In conclusion, under moderate energy supply, adequate reserves for subsequent lactation can be achieved in second- and third-parity IB sows with a daily provision of at least 17.2 g lysine over the last third of pregnancy, what implies a substantial increase in protein supply respect to traditional practices