Selective breeding - (Apr/09/2011 )

Hello; i am new to the forum.

I would like to ask you about selective breeding and the chances of producing a Taurus (bull) that displayed favourable traits and phenotypes of 2 selectively-picked cattle; thus to produce a better offspring as a result.

Taurus have 30 chromosome pairs; so what are the potential outcomes of the breeding?

How do favourable phenotypes become dominant? is that just a result of the phenotype being heterozygous dominant?

Am i correct in thinking that it is important to keep as many different phenotype combinations in genes as possible; as this allows for diversity within a species?!? if the potential phenotypic combinations were reduced; would this mean that the species would begin to look more and more alike with continued breeding?

Thank you for your time and help; much appreciated.

Your questions arent very clear or direct.
(there is so much to tall about this..)


They pick bulls (or cattle) with the right features and they breed with those and thus after a while they get offspring with that (almost) always has that feature.

Phenotypes become dominant because you breed the cattle for it.. if its a recessive feature.. after a while all the offpring has this recesive feature and the dominant ones are selected out..

And yes: its imoportant to have different phenotypes too.. this is a major problem in cattle nowedays: they are really bred in such a way they lost several important features.
(they often use incest for the cattle...)

Thats why every X generation they use "fresh" cattle that has a different bloodline to keep the cattle ok...


A good example on problems where the introduction of new bloodlines has not been used is the breeding of showdogs.. they are really misbred and abused ... Entire dograces are now about to disappear because of this idiotic breeding programs installed by "so called dog lovers"...

I am not sure if this helps a bit?

Thank you; that does help.

So what would be the probability of the breeder getting the offspring he desired; at the first time of breeding?!? very difficult...?!?

Thanks again.

Katchit on Sat Apr 9 13:00:19 2011 said:

Getting the right cattle is something that takes time. The races/species we have now are the result of years of (in)breeding.

In fact its not only about "getting" the desired feature.. its also about "removing" the ones you dont want.

Its not so easy or direct to understand or explain.

There are many factors influencing the features you need (we are not talking here about the eyecolor for example, and even eyecolor is polygenic..).


Imagin that feature X is based on 1 gene and this is gene 1 and you have gene 1D (dominant) and gene 1r (recessive)and its the recessive one you want, so if you cross dad (DD) and mom (rr) you will end up with Dr ..., so you didnt get rr... But if you then cross the child (lets say its a male) with the mother again: Dr + rr => you might get rr in the end and thus what you want....

But this is a very very oversimplified example.

And you see where problems occur: breeding often happens with "incest" relations.. and thats how animals are often bred untill they are "broken"....
No fresh bloodline= killing them in the end.

pito -

Thank you for the explanation, that makes it very easy to understand.

You have been very helpful with your replies and it is much appreciated.

Thank you for taking your time to answer.