Litter size of commercial European sow lines, can be increased by the introduction of genes from the highly prolific, but obese Meishan. At present there is little information on the feed requirements of the “Meishan” during lactation. It is likely that these requirements are different to those of commercial lean white sows, due to differences in fat reserves. In European lean genotypes “thin” sows at parturition have lost significantly less backfat during lactation than sows which are fat at parturition (Yang et al, 1989). There may also be different relationships between nutrition, body composition change and performance in different breeds. It was predicted that the M might need a higher protein to energy ratio, to complement catabolism of their higher levels of body fat reserves.