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

Summary
The conservation of genetic variability is the basis for a sustainable use of animal
resources and a decisive factor for the maintenance of vitality and performance. In
particular, small populations are at risk because an increase of inbreeding is to be
expected with loss of usable genetic variability. The aim of this thesis was to analyze
the genetic variability of the Piétrain herdbook population in Schleswig-Holstein. The
analysis of the actual situation is the basis for future concepts with regard to the
conservation of genetic variability.
The objective of the first chapter was to analyze population structure and effective
population size to evaluate the endangerment status of the Piétrain herdbook
population in Schleswig-Holstein. The following parameters were determined: the
average generation interval, variance of the family size, the increase of the rate of
inbreeding and the effective population size. For the estimation of effective
population size only ancestors of the active population were used . The average
generation interval was calculated to be 2.4 years with a slight increase since 2003.
Three methods were applied to estimate effective population size: the formula given
by Hill (1979) to estimate drift effective population size for each year and inbreeding
coefficients to estimate inbreeding effective population size obtained from the
numerator relationship matrix (NRM) or from uncertain parentage matrix (UPM). The
latter applies a probabilistic correction for unknown ancestors. Drift effective
population size has slightly decreased between 1990 and 2006. The harmonic mean
across years resulted in an effective population size of 105 pigs. The effective
population size estimated by NRM was higher at around 190 animals. Correction by
unknown ancestors (UPM) led to an effective population size of 118 animals. The
major differences between the methods NRM and UPM showed the influence of
missing pedigree information mainly caused by imported boars. The variance of the
family size in the male-female path varied extremely in the past due to the extensive
use of some boars.
In the second chapter the genetic connectedness between the five most important
Piétrain herdbook populations in Germany was evaluated. The herdbook populations
were located in Bavaria, Baden-Württemberg, Schleswig-Holstein, North Rhine-
Westphalia and Lower-Saxony. The herdbook populations were genetically linked as
a result of imported boars and the use of artificial insemination boars in the past
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