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

number of selected boars at different levels of relationship constraints and the
corresponding expected average breeding value of selected animals are shown in
Figure 2.
number of selected boars
22
20
18
16
14
12
10
8
6
4
2
0
selected boars Schleswig-Holstein
selected boars Schleswig-Holstein and Baden-Württemberg
average breeding value Schleswig-Holstein
average breeding value Schleswig-Holstein and Baden-Württemberg
1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9
constraint on relationship (%)
170
160
150
140
130
120
average breeding value
Figure 2: Average expected breeding value of selected animals and number of selected
sires at different constraints on relationship without restrictions on maximal contributions.
In general, the optimal number of boars decreased rapidly as the relationship
constraint is relaxed. The lowest achievable level of relationship in the next
generation were 2.7% for SH boars and only 1.9% if BW boars were included. The
optimal number of boars at the most stringent constraint was 16 for SH boars and 17
for SH and BW boars, respectively. At the most relaxed relationship constraint
(3.9%), the optimal number of boars decreased to two and one for SH and SH with
BW boars, respectively. Without a constraint on boars reproductive capacity,
expected average breeding value of selected animals was maximized at relationship
constraint at 3.9% for both datasets. However, a higher average breeding value of
selected animals could be achieved by including BW boars.
In a second scenario, the maximum genetic contribution of individual boars was
restricted to 10% which means that the maximum number of progeny from the same
boar is limited to a value of five animals (Figure 3). This constraint led to a loss in
genetic gain. With a maximal contribution of 10% of each selected boar, the maximal
achievable average breeding value of selected animals reduced from 160 to 140
including SH boars. Also a reduction was calculated for SH and BW boars from 163
to 148.
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