Pregnant sows in poor body condition require a high feed intake to restore body fat reserves. However, a high intake in the period following conception may increase embryo losses. The first objective of this experiment was to determine whether a high feed allowance after conception has any effect on litter size compared with a normal allowance. The second objective was to investigate the effects of body condition at conception and feed rate in early pregnancy on the components of maternal gain.

Multiparous cross-bred sows of Large White and Landrace lineage were classified subjectively at farrowing according to body condition as either fat (F) or thin (T). A single diet containing 12.5 MJ DE/kg and 150 g CP/kg was fed throughout the experiment. The fat sows were fed more generously than the thin sows during the 28 day lactation with mean intakes of 5.3 and 4.8 kg/day. This was to maintain the differential in body condition between the two groups. After weaning all sows were fed 3 kg per day until mating. Within the fat and thin groups sows were allocated at random to either 4 or 2 kg of feed per day for 30 days after mating.