Verena Gonzalez Lopez, 2011 - Institut für Tierzucht und Tierhaltung ...

Introduction
In Germany, the Piétrain pig is bred by independent herdbook breeding organizations
in which small numbers of specialized breeders are organized. With a proportion of
72% of all inseminations, the Piétrain pig is the dominating sire breed in Germany.
Since 1990 the number of Piétrain herdbook sows decreased substantially from
10,431 to 3,329 in 2009 (ZDS, 2010). The structural change has led to cooperation
between some herdbook organizations. In December 2008 eight breeding
associations founded the „Deutsche Herdbuchzucht Schwein“ (DHS). The declared
aim is a closer collaboration in marketing, genetic evaluation and representation of
interests. Three breeding organizations already implemented an overall breeding
value system in September 2009. In future, this should be extended to all member
organizations.
An indispensable prerequisite of genetic evaluations across populations is an
adequate genetic connectedness. A weak genetic connectedness will cause
fluctuations in the estimation of the average genetic merit of populations and the
genetic correlations between the same traits evaluated in different populations
(Hanocq et al., 1996; Jorjani et al., 2005). The accuracy of estimated breeding values
of individuals as well as genetic merit of populations increases with the degree of
connectedness. Therefore, genetic evaluation with weakly linked populations is
feasible, but not recommended (Mark et al., 2005). For this reason, it is essential to
have detailed and quantitative information on the genetic connectedness between
populations.
In this context, the objective of this study was to analyze the genetic connectedness
between the five most important Piétrain herdbook populations in Germany. Different
methods are applied to quantify to which extent populations are genetically linked as
a result of imported boars and the use of artificial insemination (AI) boars.
Material and methods
Data
Piétrain pig populations from five regional, independent herdbook breeding
organizations were studied. The breeding organizations were located in five regions
in Germany: Schleswig-Holstein (SH), Lower Saxony (LS), North Rhine-Westphalia
(NRW), Baden-Württemberg (BW), and Bavaria (B). Pedigree records were obtained
from the Chamber of Agriculture Schleswig-Holstein for the herdbook populations in
21