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 tota-l 1of 103 PIC pregn-an1t sows (mixed parity) were allocated to two -tre1atments: control (C, n=49) 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 45to 85of gestation over three consecutive cycles. Body weight, backfat thickness (BF) and loin depth were measured on days 45and 85of 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, P<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 (P<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.