Comparison of three-breed and backcross swine for litter productivity and postweaning performance.

Duroc, Hampshire and Yorkshire boars were mated with crossbred gilts of Duroc-Hampshire, Duroc-Yorkshire and Hampshire-Yorkshire breeding to produce 133 three-breed and 259 backcross litters that were farrowed during four seasons beginning in the fall of 1975. Three-breed cross litters were .31 +/- .27, .57 +/- .24 and .50 +/- .24 pigs larger than backcross litters at birth, 21 and 42 days, respectively, and .6 +/- .34, 2.3 +/- 1.2 and 5.4 +/- 2.4 kg heavier at these ages. The differences in average pig weight and survival percentage were small. Three-breed cross litters gained faster (.024 +/- .007 kg/day) and were younger (-4.7 +/- 1.5 days) at 100 kilograms. Three-breed cross pigs were about 3% more efficient than backcross pigs. The differences in average backfat probe and average daily feed intake were small and not significant. Breed of sire contrasts for litter traits were small and not significant. However, significant differences between sire breeds existed for postweaning performance. Also, few differences between crossbred dam groups were significant for litter size or litter weight, but significant differences in postweaning performance existed between progeny of crossbred dam groups. In general, pigs with Duroc breeding had the fastest growth rate and those with Hampshire breeding were the leanest.