Oorsig/Review
Selection for Optimal Production
Dr Ariena Shepherd
Optimal production has various definitions de-
pending on individual viewpoints. In small stock
breeding many confuse it with breeding indica-
tors for example high weaning percentages or
high growth rates. These parameters are impor-
tant but they are just tools in developing a selec-
tion system for optimal production.
Optimal production is achieving increasing yields
using cost-effective measures over long periods.
To achieve this precise breeding objectives must
be defined and the economic impact and costs
evaluated as well as possible impact on other
traits considered. The breeding objectives must
then be implemented and progress tracked.
Precision livestock farming technologies have
made it possible to evaluate individuals rather
than averages which has made higher selection
pressure possible.
Basics
Before any selection program can be implemented
basic structures must be in place. All animals
must be individually identified. Progeny must
be linked to dams and preferably to sires as well.
Recording data must be done at least once a year.
Records must be kept so that comparisons can be
done over years.
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Selection
Selection has to be aimed at the big picture. A
flock evaluation can identify the major causes of
losses and which breeding objectives can have
the biggest economic impact. Disease and health
are often the best place to start as factors are
usually easy to identify and progress is quick. In
emerging flocks or small holding flocks this can
sometimes be a problem as culling large numbers
of animals may not be possible. Also, it may be
difficult to convince a farmer that culling 30% of
his flock will improve his profitability. If this is the
case culling can be done over more than one year
but this will delay progress.
Guidelines for Production Parameters
This is dependent on area, nutrition and type of
farming system. An extensive farmer which lambs
several thousand ewes compared to an intensive
farmer lambing 500 ewes will have different
production parameters. The objective is to set
guidelines for each farm individually once the
flock evaluation is done. The best time is 6 weeks
before breeding. First cull all chronically sick
animals – mastitis, claws, abscesses. If possible
cull all ewes which have not produced a live lamb
during the last 12 months. This may be done at
weaning the following season if there are no
current records. Start identifying parasite taxis.
Many farmers are resistant to less antiparasitic
use as they think it will decrease their production
but reducing antiparasitic use in the dry season