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Line breeding - your opinions

Discussion in 'Dog Breeding' started by SpicyBulldog, Apr 7, 2017.


  1. SpicyBulldog

    SpicyBulldog PetForums VIP

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    What is everyone's opinion on line breeding? The good, the bad? Never agree with it or circumstances it should be done? Specific breed you wouldn't recommend or at least keep to lowest COI as possible? I know the UK KC has certain restrictions on it? Do they also let you check COI on potential breedings? I thought I heard this solve where. I think registries should have this available.

    I believe the gene pool in the UK for some breeds is probably smaller than the US, but certain breeds across the board have a small amount of diversity. People have the option to use dogs in other countries as well. It seems a lot is dependent on breed. Some breeds lack diversity, have small effective founder population, have polygenic health disorder that is spread in most the breed due to founder effect or popular sire issues, ect.

    I don't believe there is necessary a simple answer when it comes to line breeding, but I do believe breeders should try to keep diversity while still preserving the breed. This does not mean never line breed, having differing lines can keep diversity within a breed, you will have unrelated dogs to breed to, but if everyone starts breeding the same line (or few lines) or popular sire, ect the gene pool will quickly narrow. This has been done in a number of breeds.

    There is more to deciding on a breeding than COI or pedigree, but it is a topic worth discussing I believe.
     
  2. Moobli

    Moobli PetForums VIP

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    I am not a dog breeder. My rather basic knowledge on line breeding is that selective breeding is undertaken to fix desirable traits and characteristics. The breeder who knows their lines well will understand and acknowledge the strengths and weaknesses in their lines and will use line breeding to fix desirable traits whilst attempting to eliminate weaknesses. Of course the problem with line breeding is that you are dealing with a much smaller gene pool with the associated risk for overall genetic health and the increase of risk of recessive genetic diseases occurring.

    Basically, a breeder must always bear in mind that you get out what you put in, good and bad, and when line breeding you have to be pretty sure you know plenty about the dog you are line breeding to, be as sure as you can be that there are no serious negatives and what negatives there are will be outweighed by the positives.
     
  3. leashedForLife

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    "line breeding" is simply another version of INbreeding, & along with supposedly "fixing desired traits", it will concentrate un-desired heritable issues.
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    It's an easy trap to fall into, & a hard one to escape - the inevitable pruning of gene diversity goes hand in hand with any attempt to back-cross to a parent or G'parent, mate cousins, etc.
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  4. Rafa

    Rafa PetForums VIP

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    The Kennel Club will not register pups from inbred parentage. Inbreeding is mating father to daughter, brother to sister, son to mother, etc.

    Linebreeding, I believe, can be a good thing, where the Breeder is well informed, and with a well researched plan in mind.
     
    Katalyst, adamantis, labradrk and 4 others like this.
  5. smokeybear

    smokeybear PetForums VIP

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    People get very aerated about line breeding in dogs but the facts are that it has proved extremely successful in dogs, cattle, sheep etc etc
     
  6. labradrk

    labradrk PetForums VIP

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    As above, line breeding and in breeding are not the same.......
     
  7. leashedForLife

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    Piffle. "Line breeding" is a dilute version of "in-breeding", kinda like the Easy-Bake oven for pre-teens.
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    What do the terms inbreeding and linebreeding mean? - RSPCA ...
    kb.rspca.org.au › Companion animals
    Nov 11, 2016 -
    Linebreeding i
    s a form of inbreeding. What is close inbreeding? Close inbreeding is the mating of close relatives. The closest form of inbreeding in domestic animals involves matings between full brothers and sisters (full siblings) and between parents and offspring (collectively called first-degree relatives).



    Linebreeding | Definition of Linebreeding by Merriam-Webster
    https://www.merriam-webster.com/dictionary/linebreeding
    Medical Definition of linebreeding. :

    the interbreeding of individuals within a particular line of descent usually to perpetuate desirable characters - compare inbreeding, outbreeding.


    Inbreeding and Linebreeding
    bowlingsite.mcf.com/genetics/inbreeding.html
    What are inbreeding and linebreeding, and what effect do they have? ...
    [As establishing any 'pure breed' utilizes a] limited number of foundation dogs, all pure breeding is by this definition inbreeding, ...


    Linebreeding | Define Linebreeding at Dictionary.com

    www.dictionary.com/browse/linebreeding

    Linebreeding definition, a form of inbreeding directed toward keeping the offspring closely related to a superior ancestor.
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  8. SpicyBulldog

    SpicyBulldog PetForums VIP

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    Good explanation here.

    I understand it is a form of inbreeding, of course you are breeding related individuals / dogs of the same base line.
    Perhaps I should have asked what everyone's definition is of each, as I know it varies. If you get technical breeding pure bred dogs is "inbreeding" some breeds just about all individuals are closely related, in others you can still find fairly unrelated dogs, but they still come from the same foundation.

    You can certainly bring forward undesirable traits, people might not be aware of what's lurking in the gene pool. New test for genetic diseases are being developed all the time so that helps and knowing lines / what the dogs within a line produce. It really depends on the hereditary issue. You can concentrate or eliminate traits, good or bad. Now you can't hand pick each individual trait a dog will pass on / or inherit. Breeders can do their best by health testing AND studying the pedigrees and lines they are using. Clearly people do line breed so it can be possible to know what is in the lines. Out crossing can also yield negative results, as dogs of the same breed obviously can carry the same issues. Gene pool in pure bred dogs have already been narrowed. My main concern would be more reducing genetic diversity in individuals, this might not be a big concern in general if all is well. My concern would be specifically MHC genes, because then you can see inbreeding depression and immunity issues.

    So they only disallow 1st degree relationships? Good in theory and I've nothing against line breeding, but some line bred dogs with generations of line breeding have high COI.

    This is very true. It really depends on the specific lines. Some do not thrive or produce big negatives. In other cases breeds have been kept healthy and preserved with appropriate line breeding and unrelated individuals kept within the pool and you can take separate lines and cross them.
     
    Moobli likes this.
  9. Katalyst

    Katalyst A Lanky Lurcher and a Delinquent Dobermann

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    Inbreeding and line breeding will NOT create problems that aren't already present in the animals genotypes.
    What they will do is bring any hidden recessive traits to the surface, including those that are far from desirable.
    I'm not fond of direct Inbreeding but linebreeding when done thoughtfully and with great knowledge of your lineage for many generations is safe and can be used to fix in positive traits. It's not the devil if done right.
    In the same vein, out crossing completely with no knowledge of the lines you're crossing can result in the same problems as close Inbreeding. All it takes is the parent dogs to share the same damaging recessive or problems where both parents share genes that are allelic and on the same loci.

    I've never bred dogs but have bred many, many rodents and other small animals.
    In my humble opinion, no one should EVER contemplate breeding of any sort without at least a basic understanding of genetic inheritance.
     
  10. SpicyBulldog

    SpicyBulldog PetForums VIP

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    Katalyst I think you have some good points, these are my considerations I will add.

    If we speak of recessive diseases that are hidden in the heterozygous state, then that is true. Inbreeding or line breeding did not create the problem, it came to light because the related parents carried it from a common ancestor.

    However, if you consider that inbreeding or line breeding is done to "fix traits", that means increasing homozygous gene pairs. This includes MHC genes, therefore you could potentially create a problem. Loss of variability means the inability to fight infections and susceptibility to diseases. Increased risk of cancer and higher mortality rate. It could be a cause of issues with demodex in dogs. There was not any problem with the genes the animals carried, the initial dogs could have a good variability of MHC genes, but after generations of related breeding the variability is lost. The more variations in this system of genes the better overall. Some of these genes also provide other important functions besides those related to the immune system. Certain genes are associated with problems.

    I am okay with either, though it seems the definition of "line breeding" varies.
    How I look at it, either is done to fix traits. Inbreeding will likely fix traits quicker by increasing homozygous genes at a higher rate. Line breeding still achieves this, but it might take longer. At least in theory. In either case you have the same chance to bring forth and fix good or bad traits relative to the breeding being done, so I do not believe inbreeding to be "unsafe" or line breeding to be necessarily safe. What I am saying is if one bred a brother and sister theoretically it is expected that they would be homozygous for 25% of their genes. Let's say a line breeding is done and it could be expected that 9% of the offspring`s genes would be homozygous. In the inbreeding it is probable that more of the genes would be homozygous, but one cannot say if that would be good or bad in itself and if it is automatically for more defective traits. Of the 9% in line breeding there could exist a more deleterious genes. Of course in pure bred dogs where there has already been inbreeding and a narrowing of the gene pool I think that COI cannot tell us exactly what to expect, homozygosity is possibly going to be higher. Clearly even if you breed unrelated dogs they would have some of the same recessive traits in their breed. Even different breeds carry some of the same genes from breed to breed. Therefore an uneducated designer dog breeder who crosses breeds (mating with 0% COI) could yield pups who have a recessive disease carried by both parents and clearly having some homozygous genes in the offspring.

    As well in time assortative mating will increase homozygous genes even though you have as close to 0% COI of inbreeding as possible. So potential for defects popping up is still there when attempting to fix physical and behavioral traits that way. I see people put line breeding down as terribly bad and risky, yet breed pure bred dogs. To me it shows a lack of understanding in genetics. They appear to be under the delusional that by not line breeding the offspring produced will never be at risk for genetic problems. There is always a chance you lose some important diversity even though they are unrelated, or that by chance both parents carry a disease from some dog way back in the pedigree as being pure bred share some ancestors somewhere. The only thing not line breeding is protecting them from is a novel recessive disease.

    I very much agree. A lot of byb are out there randomly breeding unrelated dogs, but producing health or other issues in the pups. I believe Padgett gave an example of how inbreeding a pair of digs who you know do not carrying a known genetic disease would be a safer bet and less risk than out crossing to a dog of unknown genetype when the allele frequency of disease can be approximated within the breed.

    Couldn't agree more.
     
    #10 SpicyBulldog, Apr 9, 2017
    Last edited: Apr 9, 2017
    Katalyst likes this.
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