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What's Performance Recording all About?
The reason we record information on how animals perform,
is so that we can identify and put a performance estimate (EBV or Estimated
Breeding Value) on those parts of an animal (i.e. its genes), which are
involved in transmitting production related performance to its progeny.
Animals, which breed superior performing progeny, cannot be identified
accurately by "eyeballing" them.
What you see in an animal (its phenotype) is a combination
of:
1. Its genotype (the sequence of genes that make up the animal).
2. A number, of what are known as, environmental influences such as
grass, sunlight, wind, rain, trace elements, drenches, parasites, sickness
and social stress expressing themselves as muscle, fat, bone etc.
How an animal performs will depend very much upon
the extent to which it is exposed to these influences. For example, how
much grass it eats, the number of parasites it is exposed to and how many
drenches it receives or whether certain trace elements are absent in its
diet. While all these influences are constantly changing and hence affecting
the performance of the animal, the animal's genotype (genetic makeup)
remains the same.
"Animals do not pass on to their progeny the
effects of the environment. Animals pass on their genes, which make up
their genotype."
Therefore in selecting an animal, in the absence of any
performance information, you can quite easily be misled by its size,
simply because the animal may have had access to the most grass and not
because it has the best genes for growth.
Effective performance recording involves keeping the influences
of the environment the same for each animal while measuring its progress.
This ensures that the difference in performance between animals can only
be the result of the difference in their genetic makeup (genotype). With
these genetic differences now isolated, estimates of how the animals are
likely to breed (EBVs) can be made.
Some breeders who are sceptical about using EBVs to select
animals, often place heavy emphasis on pedigrees. In doing so, they are
linking pedigree information to performance, that is, they believe certain
bloodlines perform better than others. You will note that on this matter,
performance recording sceptics and believers agree.
Summary
Performance recording involves:
> Giving animals within a recorded group the same opportunity to
perform.
> Taking various measurements on these animals.
> Using these measurements to produce EBVs, which are estimates of
how these animals will perform as parents.
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