Jings, that's as quick as Facebook! _________________ Annie
Handle every situation like a dog, if you can't eat it or play with it, just pee on it and walk away
Thankyou for posting the line-breeding links. They are both useful as introductions, but it is important to understand where line-breeding or out-crossing is most useful. The GSP article refers to the successful line-breeding of dairy cows, and also the hybrid vigour of the F1 out=cross & loss of this advantage if the F1's are bred together.
The missing piece of the explanation is the heritability and heterosis of the traits in question. Traits with high heritability (like milk production) respond well to selection and line-breeding, while traits with low heritability but high heterosis (like weaning weight of calves) respond well to out-crossing. As heritability goes up, heterosis goes down and vice versa.
Dairy farmers have known this for years because their livelihoods depend on the knowledge. Hence, they want highly inbred dairy cows for milkers crossed to a beef bull to get the beef genes plus the extra weaning weights due to heterosis. Heterosis means that the weaning weights are around 5% greater than the average of the weaning weights of the purebred dairy & purebred beef calves. A 5% higher weight for no extra feed is an important economic incentive for the farmer to out-cross for this trait. Of course, the farmer will want the best dairy bull that produces line-breeding advantages to put over his best dairy cows to get his replacement milkers.
Now, what does this mean for dog breeders? Well, first we need to know the heritability of the traits we are seeking to influence, then we will be better able to decide if line-breeding or out-crossing is the way to go. It gets tricky when we try to juggle several traits at once, but the point is that line-breeding and out-crossing are important tools in the hands of the breeder and saying that we should only use one or the other is starting with a big handicap.
Yes, I agree with all of that. I would think some of the traits we should be looking for are those which make the Brittany or Epagneul Breton what it is - namely cobbiness (rounded ribcage with short loin). head proportions, earset, working ability. There are more but that's a start. I have always line bred for those (admittedly I don't breed a great deal) and seem to get pretty typy dogs. Only a few are shown though, most are worked.(not trialled) _________________ Annie
Handle every situation like a dog, if you can't eat it or play with it, just pee on it and walk away
Yes, I agree with all of that. I would think some of the traits we should be looking for are those which make the Brittany or Epagneul Breton what it is - namely cobbiness (rounded ribcage with short loin). head proportions, earset, working ability.
These are the traits that I am interested in selecting for, too. Is there any information about the heritability or mode of inheritance of any of these in the Brittany?
Goldie can answer this one - she's the expert on genetics, I just look at the dogs and pedigrees. _________________ Annie
Handle every situation like a dog, if you can't eat it or play with it, just pee on it and walk away
If you are interested in which physical traits are dominant over others I would suggest reading the old book of Leon F Whitney it contains many of the early days breeding experiments evaluating traits such as long legs, longer ears, heads, etc.
In breeding Brittanys for the past 35+ years I have found that the hardest traits to "maintain" are small ears, wide back skulls, excellent shoulder angulations. Once you loose correct heads..ie get longer muzzles or down in the face attributes it will take at least 2 generations to correct for "stability" and get prepotency back.
So heads and shoulders are my biggest focus to "keep" the rest can be "fixed" in one generation if needed for the most part. This is working with AB lines. In French lines I find it hard to keep correct front legs...these lines tend to be elboed more and have a greater tendency to "Bandied legs" excessive bowed rears which result in higher tendency for patellar problems. Certain lines seem to have a higher incidence of Umbilical hernias, some lines have a tendency towards dog to dog agression, and the ones with the really wide backskulls also have a greater tendency to undershot jaws. Migh be the so called "boxer" influence that joncour speaks of LOL _________________ Goldie Coats
Wyngold Britanys
Bend, OREGON, USA
In French lines I find it hard to keep correct front legs...these lines tend to be elboed more and have a greater tendency to "Bandied legs" excessive bowed rears which result in higher tendency for patellar problems
I think you may be right - I've seen a lot of 'elbow out' dogs over my judging career since 1992. Cowed hocks is another bad trait I've seen a lot of, as well as loose hocks - some of them look like they are knitting jumpers lol _________________ Annie
Handle every situation like a dog, if you can't eat it or play with it, just pee on it and walk away
Goldie, you have a point During my recent visits, I have found a good number of dogs with narrow forechests and quite upright in shoulder. It gives an odd stance. Going round some kennels- also small ones- you find a vast amount of dogs lacking deep chest and width between front legs. I guess they work well so are bred from .
As heads are important to me, I have found many narrowish skulls, longer muzzles which don't do anything for me. Front face lacking too. Longish ears not always well placed...Where has the chiselling gone? and that very alert expression?
I have seen some very pleasing and soft heads at Patrick's, not all obviously but a good few very good ones.
Last edited by Patricia on Wed Sep 30, 2009 5:32 pm; edited 1 time in total
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During my recent visits, I have found a good number of dogs with narrow forechests and quite upright in shoulder. It gives an odd stance. Going round some kennels- also small ones- you find a vast amount of dogs lacking deep chest and width between front legs. I guess they work well so are bred from .
