The improvement in sow productivity over the past decade raises the question of whether feeding recommendations in lactation are still appropriate for high prolific sows and their feed intake capacity. The present study aimed at testing the impact of increasing feed allowance in the lactation period on the sow performances and their litter. At farrowing, 90 sows, from 1st to 6th parity, were randomly assigned to one of two feed allowances in lactation: standard (ST) or high (HI). A single lactation diet was formulated to contain 14.1 MJ/kg digestible energy (DE), 186 g/kg crude protein, and 9.5 g/kg digestible lysine. The feed allowance of the ST sows was calculated to cover the energy and nutrient requirements of each sow based on the Swiss feeding recommendations. Sows of the HI group had ad libitum access to the feed. Litters were standardized to 12 piglets on average. The individual feed intake was recorded on a daily basis. Sow body weight and backfat thickness were measured at farrowing and then weekly until weaning. Piglets were weighed at birth and at weaning. Data were analysed with a mixed model considering the feeding system, the parity, and their first order interaction as fixed effects and the sow as random effect. As expected, the average daily DE and nutrient intakes were 20% greater (P<0.001) in the HI group, representing a 1.1 kg-greater average daily feed intake compared with the ST group. Neither the piglet weight at weaning (8.0 vs 7.7 kg, respectively) nor the average daily gain in the suckling period (230 vs 217 g/d, respectively) was affected by the feeding system. Nevertheless, when data are standardized by the lactation duration and the litter weight gain, HI sows lost less (P=0.04) weight compared with ST sows (5.9 vs 9.9 g/d per kg litter gain, respectively). Similarly, the daily backfat loss per litter weight gain was 3-fold lower (P=0.04) in the HI than in the ST sows. The similar litter performances suggested that milk production was unaffected by the increase in DE and nutrient intake, while the lower weight and backfat losses in the HI group reflect reduced mobilisation of body reserves.
