To help resolve the dynamics of fatty tissue mobilisation, and interactions with milk yield and reproductive performance, the experiment reported here takes gilts and sows over four parities to one of two levels of strategic fatness at parturition, and then studies the consequences of high or low lactation feed intakes in conjunction with strong or weak milk withdrawal potentials as achieved by manipulation of litter size.

One hundred and two Large White x Landrace F1 hybrid gilts were purchased from the Cotswold Pig Development Company Limited at about 30 kg live weight. At mating, animals were allocated at random to one of B treatments comprising: two levels [fat and thin) of target backfat thickness at parturition (10-14 mm. T vs 20-24 mm. F): two daily feeding levels (high and low) during 4-week lactation [3 kg, L vs ad libitum to a maximum of 7 kg. H): and two sizes of sucking litter (5 vs 9 in parity I. and 6 vs 10 in parities 2. 3 and 4).