Study of the genetic variability of selected and local breeds using pedigree information

The pedigree analysis of four selected pig breeds (Large White dam line, Large White sire line, French Landrace and Piétrain) and five local breeds (Basque, Gascon, Blanc de l’Ouest, Limousin and Bayeux) was performed using pedigree information. Pedigree completeness (estimated from the percentage of known ancestors by generation) was favourable in each breed : 10 generations equivalents were known for the two Large White lines and the French Landrace, 6.9 for the Piétrain breed, and between 7.9 and 9.4 for the local breeds. The rate of inbreeding increased in all populations, and reached a high level in local breeds (from 8 to 18%) and a lower level in the selected breeds, much larger in size (from 2.2 to 4.6%). The analysis of founders and ancestors through probabilities of gene origin showed a stability of genetic variability in the five local breeds within the 1995-1999 period. In the same time, the genetic variability was strongly reduced in the selected breeds, particularly in maternal lines, where bottlenecks seem to be more frequent. This study proved the efficiency of the conservation programme and highlighted the need for a better control of genetic variability in selected breeds. Such a control could be reached either using management rules for the use of breeding animals, or adapting breeding methods.