The present experiment was designed to investigate the influence of variations in energy intake during both pregnancy and lactation on changes in body weight, backfat and body composition of the sow after four parities and the extent to which these may have influenced overall sow productivity.

The experiment has been designed in a 2 x 2 factorial arrangement involving two levels of feeding during both pregnancy and lactation. The feeding levels in pregnancy were planned to produce net maternal body weight gains of 30kg (H) and 10kg (L). At each of these, two feeding regimes were applied during a 3 week lactation, one being at a conventional level (H) and the other 25% below this (L). The experiment thus involved four groups of animals given different levels of feeding during both pregnancy and lactation, designated: High-High (HH), High-Low (HL), Low-High (LH), Low-Low (LL). No creep feed was provided to the piglets during the suckling period. At the start of the experiment the gilts weighed 115kg live weight with a backfat thickness at the P2 position of 18mm. They remained on the same treatment throughout four parities and were slaughtered after weaning their fourth litters when the carcasses were retained for analysis. Data are presented from 66 sows; 17(HH), 17(HL), 16(LH), 16(LL).