The Simbra Breed

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In the mid-seventies we were the first Society 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.  Since the beginning this policy was also by means of the Simbradex applied to the Simbra.

Why is ICP history?

After visual evaluation the judge has two six year old cows in his final selection, one of which must be placed first according to reproduction.  The Breed Society’s Constitution stipulates that reproduction must be put at the disposal of the judge and taken into account at all large shows.  Cow A has an ICP of almost 400 days and cow B 365 days – no argument – he places cow B with her ideal ICP of 365 days first.  Let us have a look at the records in the office.

Cow A (ICP 400) calved for the first time at 27 months, is again certified in-calf and will wean her 4th calf in a month’s time.

Cow B
(ICP 365) calved for the first time at three years is not in calf and only had her  4th calf a week ago.

If you were to calculate the Simbradex of the two cows mentioned above you would find that cow A ((ICP400) has a Simbradex of 103) compared to (93 for cow B (ICP 365)).  With the Simbradex displayed on the cow’s ring card, the judge will not even take cow B in account.

Simbradex, 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 Simbradex is that a cow which calves for the first time on 33 months (national breed average 33.4) and re-calves every 365 days has an ideal Simbradex of 100.

The Simbradex 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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