Short v Non-Short breeding

[jem]

Sorry, being fairly new, I am not clear on what crosses produce what calves...

Does non short x non short always produce a non short?

Does non short x short produce 50/50 short v non short?

Is it correct that animals can be short but not carry the achondraplasia gene?

Thanks for your help.

[Duncan MacIntyre]

Many years ago Dexters were mostly described as long or short. Traditionally only shorts were considered really as Dexters, and the longs might be culled or in the distant past registered as Kerries. The term non short was coined in an attempt to be less discriminatory as long legs became more popular and most breeders came to realise that if they were to avoid bulldogs they could not breed short to short. So in broad terms short meant bulldog carrier, non short meant non carrier. The term medium leg arose when some, eg Woodmagic herd, began to produce non carrier dexters which were shorter than the average long leg, but I have never found the term very useful. In 21st century it is probably much more useful to restrict categories to carrier and non carrier with respect to the bulldog gene. The appearance of the two categories can almost overlap as some breeders of non-bulldog carriers are reducing the height and some carrier cattle are getting a bit bigger, and it can be difficult for even experienced breeders to tell. Fortunately we now have DNA testing to give a definite answer.

But to go back to your question, a non short bred to a non short cannot produce a short, if you accept that the traditional short legged dexter was so because it carried one copy of the chondrodysplasia gene.

non short x non short = non short

non short x short = 50% short, 50% non short

short x short = 25% non short, 50% short, 25% bulldog

It is perfectly possible to breed a non short shorter than some of the tallest shorts, so in that sense you may see a dexter which looks short but does not carry the chondrodysplasia gene.

Duncan

[jem]

Excellant answer, thank you. It's all much clearer now.

[Woodmagic]

Yes, Duncan an excellent explanation, can I just add for the benefit of those readers not into genetics, the ratios are averages and will work out in the long run, but in practical breeding with just a few births you may well have a consecutive collection of just one type.
Beryl (Woodmagic)

[Broomcroft]

There's a fact sheet on the American Dexter Cattle Association website. Click on this link http://www.dextercattle.org/genetics.htm then go to Chondrodysplasia.



Edited By Broomcroft on 1250850453