Effects of extra feeding in mid-pregnancy for three successive parities on lean sows' productive performance and longevity

The aim of this study was to investigate the long-term effects of increasing feeding allowance during mid-pregnancy in sows. A total of 103 PIC pregnant sows (mixed parity) were allocated to two treatments: control (C, n49) were fed 2.5 3.0 kg d 1 (12.1 MJ ME kg 1) and extra-fed (E,n 54) received 2.0 kg d 1 of the same feed from day 4 5to 8 5of gestation over three consecutive cycles. Body weight, backfat thickness (BF) and loin depth were measured on days 4 5and 8 5of gestation, farrowing and weaning. Litter and sows performance were recorded during lactation and post-weaning. Overall culling rates were 61 and 67% for C and E groups, respectively. After three cycles, E sows showed a positive BF balance in contrast to C sows (E 1.46 mm and C 1.81 mm, PB 0.05). In cycle 3, E sows presented greater piglet birth weights than C sows, being mainly evident in sows that were nulliparous at the onset of the experiment (PB 0.05). Extra-fed sows showed a greater incidence of mastitis-metritis-agalactia syndrome than C sows (P 0.003). Thus, increasing feeding allowance during mid-pregnancy positively affected BF balance and birth weight in nulliparous sows,but impaired the sows' ability to produce milk in the long-term