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In the mid-seventies we were the first breed in
Southern Africa
to introduce reproduction into the show ring by judging cows
according to ICP (inter calving period). After a couple of
years we noticed that ICP per se is not an accurate
measurement of reproduction and we were compiled to use a
better yard stick. We then developed Simdex (SIMmentaler
reproduction inDEX) in the mid-eighties and introduced it
with great success amongst others in the show ring. The age
at last calving, number of calvings, inter calving period
and, if applicable, number of embryo flushings are expressed
in one comparative figure by means of Simdex.
Why is ICP history?
In the “five-six year old cow in milk class” the judge has
two cows of the same age in his final selection. He must
now consider reproduction because the breed society’s
Constitution stipulates that reproduction must be put at the
disposal of the judge and taken into account at all shows.
Cow A has an ICP of 400 days and Cow B 365 days – no
argument – he places cow B with her ideal ICP of 365 days
first. Let us take a look at their reproduction records:
Cow A (ICP 400) calved for the first time at 2¼ years, is
again certified in-calf and will wean her 4th calf soon.
Cow B (ICP 365) calved for the first time at three years
and only had her 4th calf a week ago.
The Simdex of the cows is 100 for cow A (ICP 400) and 90
for cow B (ICP 365). With this Simdex information displayed
on the cow’s ring card, the judge will not even consider cow
B with her ideal ICP.
Simdex, a trade name of the Society, is according to
experts the best reproduction measurement and a couple of
other instances copied it already. The basis of Simdex is
that a cow which calves for the first time on 30 months
(national breed average 31 months) and re-calves every 365
days has an ideal Simdex of 100.
The Simdex formula is:
200 – [{(X – Y) /Z} *100]
Where X = Age at last calving in days, Y = Number of
flushings *56 and Z = 913 + (365* (number of calvings –1).
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Simdex Table
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