For a crossbreeding experiment six lines of pigs were developed from six breeds: Belgian Landrace (B), Pietrain (P), Dutch Landrace (N), Dutch Yorkshire (G), Duroc (D) and Hampshire (H). Out of 10 different litters per line, one female and one castrate male were housed and fed individually from 20 to 96 kg. All pigs were offered feed twice daily for 20 min exactly.
Maximum differences in feed intake between the lines increased from 150 g at 25 kg to more than 500 g at 95 kg live weight. Daily intake of Pietrain pigs was lower than that of all other lines. Differences between the N, H and G lines were small. The difference between the feed intake of males and females increased from zero at 27 kg to 230 g at 75 kg. Differences in daily gain were greatest between the P and G lines, and doubled during the growing period from 80 g to 170 g.
Differences in daily gain between the N, H and B lines were small. Pietrain pigs and, to a lesser extent, Belgian Landrace pigs produced more meaty carcasses but both had poorer meat quality than other other lines. It is concluded that differences in feed intake might be the main causal factor for the existence of differences between biological types of pigs.