2.4.2. Selection strategy
A 2-stage-selection is performed in the dam-line:
- Each boar is mated to 10 sows, resulting in five selection
candidates per sow which are tested for early ADG (birth
to 20 kg), ADG during the growing/finishing period, leg
condition and backfat thickness at 100 kg live weight. Leg
condition at 100 kg (LEGf) is also assessed as a correlated
response to selection for leg condition of sows, but it is not
included in the breeding goal. Carcass lean content is
measured on the slaughtered animals at the slaughter
houses. At the end of the finishing period, BLUP-EBV
selection for young boars and sows is performed,
including their own performance, performance of seven
full sibs and 72 half sibs for the same traits, and on
additional pedigree information for all traits. No second
selection step is included for boars and thus the new
generation of 40 boars is selected out of the 400 tested
candidates (400 litters with 1 entire male/litter). In this
first selection step, 800 female candidates are selected out
of 1600 candidates (400 litters with 4 females/litter).
- In the second step of selection, the 800 gilts are mated
with the boar-line boars to produce crossbred litters. Half
of the 800 sows are selected for the next generation of
sows in the purebred dam-line. The selection was based
on BLUP-EBV, including sows' own performance during
lactation (leg condition, litter size, piglet mortality and
mean piglet weight) and weaning-to-mating interval and
performance of one full sib and 18 half sibs for the same
traits. Survival of sows between the first mating and the
end of the weaning of the first litter (SSI) and survival of
sows between the first and the second parity (SSII) are
recorded, but due to very low heritabilities, these traits are
not included in the breeding goal. They are recorded to
verify correlated changes with leg condition and weaningto-
mating interval.