Simmentaler Joernaal 2013.indb

Simmentaler - Feed the World
Wetenskaplik | Scientific
98
Graph 1
Graph 2
As illustrated in the Graph 1, the greatest increase in
effectiveness is observed going from 1 animal to 2
animals in a contemporary group. That is, a record in a
single animal contemporary group is not effective while
a performance record in a contemporary group of 2 is
50% effective.
The next consideration is the effectiveness of performance
records of progeny when calculating the EBVs for an
individual sire. If all calves in the contemporary group
are by the same sire, then the performance records
may be effective when calculating EBVs for the calves
themselves, but have no effectiveness when calculating
the EBVs for the sire. This results because there are no
calves by other sires to which their performance can be
compared. The key is therefore to have as many sires
represented per contemporary group. (at least two,
preferably five or more)
The general aim for any herd should be to maximise the
contemporary group size.
Standard Practice
As a basic rule breeders should ensure all contemporary
groups meet the following requirements:-
1. four calves (excluding twins and ET calves)
2. bred from at least two different bulls
3. of the same sex
4. within one herd
5. exposed to the same management conditions
6. and born within 45 days from each other
Breeding strategies followed by the Breeder should
take cognisance of the culling strategies which may be
applied later in the life of the contemporary groups in
order to maintain effective performance recording.
Effective performance data collected later in the life of the
animal (400 days, 600 days, with scrotal measurements
and at scan data collection) requires the application of
the same principles.
Standard Practice
As a basic rule breeders should ensure that
contemporary groups meet the following requirements
at the time of measurement of 400 days, 600 days, with
scrotal meas urements and at scan data collection:-
1. four calves (excluding twins and ET calves)
2. bred from at least two different bulls
3. of the same sex
4. within one herd
5. exposed to the same management conditions
6. and borne within 60 days from each other
One of the most common questions asked by breeders
with a relatively small herd is “what size herd do you
need to obtain effective EBV’s?” The answer depends on
the ability of the breeder to apply the constraints for an
effective management group as best as possible.
There are a number of strategies that breeders can use to
ensure they maximise the number of calves included within
each contemporary group, maximise the effectiveness of
each record and subsequently maximise the results they
obtain from their performance recording. Although these
strategies are of particular importance to smaller herds,
they should also be considered by larger herds as a
means of fine tuning their performance recording.
The following strategies briefly what breeders with
small (and larger) herds can do to maximise their EBV
accuracy.
Firstly, small herds must try and ensure there are at
least two animals that meet the above criteria to ensure
the performance records for their animals are effective
and they obtain effective results for the calculation of
EBV’s. Where there is only one animal represented
in a contemporary group, there are no other “similar”
animals to which it can be directly compared and thus
the performance submitted for it will not be used in the
EBV analysis.