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

where a i is the proportion of known ancestors in generation i and d the number of
generations that is taken into account.
In addition, known ancestors were used to compute the complete generation
equivalent for each individual j as
n
j
∑
1 ,
gij
i=
1 2
where n j is the number of ancestors of individual j, and g ij is the number of
generations between individual j and its ancestor i (Boichard et al., 1997). Finally, the
maximum number of generations traced was obtained as the number of generations
between an individual and its most distant known ancestor. The calculations were
carried out for the whole pedigree file as well as for each population.
Inbreeding and average degree of relationship
The individual inbreeding coefficient (F) is defined as the probability that an individual
has two identical alleles by descent (Wright, 1931). The additive genetic relationships
among all pairs of animals and the individual coefficients of inbreeding were
computed based on the numerator relationship matrix (NRM). Furthermore, the
average relationship coefficient (AR) for each individual was calculated as the
average of the coefficients in the row corresponds to the individual in the NRM. The
AR is defined as the probability that an allele randomly chosen from the whole
population is present to a given animal (Gutiérrez et al., 2003).
Measure of connectedness
In this study different methods were applied to describe the degree of connectedness
between the herdbook populations.
1) Number of common boars
The number of boars in common in two or more herdbook organizations is also used
by Weigel et al. (2000) and Thorén Hellsten et al. (2008) as a measure of genetic
connectedness in cattle and horses.
2) Genetic similarity (GS)
The genetic similarity is a relative measure and was computed as the proportion of
progeny of boars with progeny in two herdbook populations, relative to the total
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