Menu

Stay in Touch
Sign up for ENews
Subscribe Now

Unlimited access >

Menu

Linebreeding

Sport Horse Breeding
#81

[QUOTE=paulamc;7202175]
There is not much point looking at a 5 generation pedigree of a horse to determine how much linebreeding and inbreeding there is
with Nearco and Ribot, the duplications dont start until the 4th and 5th generations really but both horses , particularly Nearco are inbred to superior females, sons and daughters of mares, and alot of sex balanced line breedingwhich you will not see often until you go a bit further back

Paulamc[/QUOTE]

Absolutely there is! :lol: If there isn’t any inbreeding or linebreeding in the first five generations it means that there was a certain amount of outcrossing. If you go backward in the lineage in any breed there are going to be common ancestors.

Nearco and Ribot certainly were not the result of sibling or half sibling or mother/son or father/ daughter crosses. That was my point.

#82

[QUOTE=DownYonder;7201304]
Look at it now. I edited Ahorn’s pedigree to show his sire as Alme instead of Alme Z.

Leon Melchior had/has an annoying habit of adding “Z” to the name of horses he buys, which causes a certain amount of confusion when trying to research bloodlines. And just as annoying is the KWPN habit of renaming horses from other registries to fit its naming conventions. Thanks to Melchior and KWPN, the great Ramiro shows up in bloodlines as Ramiro, Ramiro Z, G Ramiro, and G Ramiro Z. :rolleyes:[/QUOTE]

Almé stood for a time at the Zangersheide, when he did, he appears in the pedigree as Almé Z. When he was standing in France, he was just Almé.

I would assume that the different listings for Ramiro also reflect a timeline as to where he was standing.

Guess they didn’t anticipate the internet and brainless spreadsheet sorts that couldn’t ignore slight discrepancies while keeping the big picture in focus. :lol:

#83

[QUOTE=grayarabpony;7201326]
And the point of your posting his pedigree is what? He’s an unproven 2 year old.

This one: http://www.chronofhorse.com/forum/showthread.php?408479-Jaguar-Mail-colt-How-will-these-bloodlines-be-regarded[/QUOTE]

The point…? Really? I thought this thread was about line breeding. Isn’t his pedigree line breeding?

Unproven 2 yo…Honestly? (He’s still a yearling, for a few more months).

Surely you must be aware that at some point, EVERY horse is an unproven 2 yo!

I guess the good thing is you won’t be able to hold that against him forever.

In a few more years, he’ll either be a dud, or not a dud. That’s really all I expect at this point! Who would ask for more?

#84

[QUOTE=poltroon;7201341]
Back to the OP’s post:

To my mind, this question is very different if you are looking at a living horse on the ground versus a theoretical mating.

The risk of inbreeding is that you are more likely to double up on unfortunate recessives.

HOWEVER. Once you have an individual on the ground who appears healthy and useful, you can assume that there are no especially dangerous recessives in that individual, at least not to any greater extent than any other horse may have. (After all, outcrosses can create dangerous recessive combinations too.)

So, if you’re looking at a very young filly who is not yet in work, you might be a bit wary. But if this is an older filly and she’s strong and healthy and fabulous, I’d have no reservations on buying her as a performance animal. As a breeding animal, a horse that is linebred or inbred and also a strong, useful individual is somewhat more likely to pass on those characteristics you admire.[/QUOTE]

I wanted to address this post again, the third para.

If you breed a carrier and non-carrier of a recessive gene, on average (always assuming no recombination), you have a 1 in 2 chance of getting a carrier. If you breed 2 carriers, 1 in 4 will be doubled up, 2 in 4 will be carriers, and 1 in 4 will be free of that gene.

It’s important to note that not all genes are simple dominant and recessive, on or off. There’s the interplay of environment and other genes to take into account. So, while a parent may not show an effect by the age of 10, the offspring might, or even sooner.

#85

[QUOTE=M. O’Connor;7202272]
The point…? Really? I thought this thread was about line breeding. Isn’t his pedigree line breeding?

Unproven 2 yo…Honestly? (He’s still a yearling, for a few more months).

Surely you must be aware that at some point, EVERY horse is an unproven 2 yo!

I guess the good thing is you won’t be able to hold that against him forever.

In a few more years, he’ll either be a dud, or not a dud. That’s really all I expect at this point! Who would ask for more?[/QUOTE]

Lots of horses are line bred. If you’re talking about line breeding, I’d assume you’d want to discuss the advantages and disadvantages. A bit difficult to do with an unproven long yearling. Also, if you think the thread is a train wreck, why are you posting?

#86

[QUOTE=beowulf;7201291]
I love Jaguar Mail. What an interesting thought. I will have to see how your Cougar progresses. JM has, on his TB side, one of my favorite sporting lines to see in a TB pedigree. What are your aspirations for Cougar?[/QUOTE]

We will let him grow and develop. He is for sale, so maybe someone else will let him grow and develop. Otherwise, we will just keep putting one foot in front of the other in a logical manner, and see what happens.

His dam is well started over fences, and has started showing. Happy to report she is far from a dud–in fact, she is starting to look amazing. Jaguar Mail went to the Olympics, and the next year was young rider champion in France with a good girl rider.

I am told our Cougar Mail has a great temperament. I have seen him only a few times since weaning. He’s with Junior Johnson at the moment, and I’m getting great reports.

Since he’s only a baby still there’s a LONG road ahead; like all unproven colts he’ll be on ‘probation’ as we watch him develop, to see whether he is a stallion candidate or not.

#87

I’ll take a stab at answering politely. As for advantages…

What I was after in this pedigree was to bring forward and strengthen the influence of several important older bloodlines (Buckpasser, Boran, Almé, Turn To) that have in most horses receded into the past.

Whether it works for performance and/or for breeding or not remains to be seen. Breeding horses is a long game. I’ll get back to you in 6 years (if I’m still at it) and let you know how it all turned out.

I think greyarabpony has a point in that you can’t assume that all is well when an individual horse appears to be ok…however, we are much more advanced now in our knowledge of which diseases and traits are genetic in nature. It’s to be hoped that something like HYPP would be more quickly evident in this day and age with the consequences of inundating the gene pool with a defect better understood.

In any case since it does take a few generations to assess the quality of a particular strategy one way or another, but that day does come eventually. Our yearling is already our second generation–it will be interesting to see the third, if indeed we get that far (which is not a given). As we are in close touch with our mare’s dam’s breeder, we feel like we have a good handle on our side of the equation. Jaguar Mail’s sire and dam are also very known quantities so all that can be done now is to wait. In the meantime, we can look to the pedigree with some hope, as it contains many names that were both good producers and performers.

#88

This is incorrect. Carrier (heterozygous for a deleterious recessive autosomal allele) versus clear (homozygous for the dominant autosomal allele) matings result in 50% carrier and 50% clear.

#89

I know that GAP knows this because she has indicated in the absence of recombination, but it is just one of my biggest pet peeves to always talk about inheritance in Mendelian terms. It is improbable that any of the “recessives” we are talking about are inherited that way.

What makes linebreeding so dangerous is that one is often breeding for a phenotype. In order to do this we increase the percentage of alleles that contribute to this phenotype in the offspring. However, we cannot do this by breeding the gene for amazing top line to another gene for amazing top line since it does not exist. Instead the trait of amazing top line is coupled to genotypic determinants. Unfortunately these desirable traits may be inherited with the traits that we do not want (ie disease ect).

It serves little point to discuss this inheritance in terms of 25/50/25, because we know that this is not accurate (even if there was Mendelian inheritance there would always be recombination). We cannot diminish the risk in this way and have a serious discussion about the risks of linebreeding. This is why knowing the horses that you breed is very important. Knowing the family of horse implicitly will aid in the decision to linebreed as you will have a better understand of how closely associated the desireable trait is to other traits that may exist that you do not want (if we had the ability to map all genomes, which is cost prohibitive now, this would be indicated by the distance away from each other two traits are on the chromosome, as those close together will be more likely to be inherited together).

ETA: All of that rambling was made to indicate that it is very important in dealing with traits in horses to consider penetrance as well as linkage. End rambling.

#90

Sorry, mating a heterozygote to homozygote results in 50 per cent inheritance of the recessive and not 25 per cent.

Stoney, inheritance of genes don’t often vary THAT much from the Mendelian model. I remember a breeder on here likening recombination to the genes all being shaken up and recombined – not true. The law of segregation and independent assortment still applies to genes on separate chromosomes for the most part.

Inbreeding is a much more haphazard way to discover gene linkage than studies in the lab.

#91

[QUOTE=M. O’Connor;7202268]
Almé stood for a time at the Zangersheide, when he did, he appears in the pedigree as Almé Z. When he was standing in France, he was just Almé.

I would assume that the different listings for Ramiro also reflect a timeline as to where he was standing.

Guess they didn’t anticipate the internet and brainless spreadsheet sorts that couldn’t ignore slight discrepancies while keeping the big picture in focus. :lol:[/QUOTE]

Yes, I know that. But thanks for the insult - I am one of those “brainless spreadsheet sorts” who finds it really aggravating that people change the names of BREEDING HORSES to aggrandize their own egos.

#92

Sorry, mating a heterozygote to homozygote results in 50 per cent inheritance of the recessive and not 25 per cent. Typo on my part, and that much more reason not to add something like Czantiago to a gene pool.

Stoney, inheritance of genes doesn’t vary THAT much from the Mendelian model. Much depends on whether or not genes are on separate chromosomes. The laws of segregation and independent assortment still applies to genes on separate chromosomes, for the most part.

#93

[QUOTE=M. O’Connor;7202290]
I’ll take a stab at answering politely. As for advantages…

What I was after in this pedigree was to bring forward and strengthen the influence of several important older bloodlines (Buckpasser, Boran, Almé, Turn To) that have in most horses receded into the past.

Whether it works for performance and/or for breeding or not remains to be seen. Breeding horses is a long game. I’ll get back to you in 6 years (if I’m still at it) and let you know how it all turned out.

I think greyarabpony has a point in that you can’t assume that all is well when an individual horse appears to be ok…however, we are much more advanced now in our knowledge of which diseases and traits are genetic in nature. It’s to be hoped that something like HYPP would be more quickly evident in this day and age with the consequences of inundating the gene pool with a defect better understood.

In any case since it does take a few generations to assess the quality of a particular strategy one way or another, but that day does come eventually. Our yearling is already our second generation–it will be interesting to see the third, if indeed we get that far (which is not a given). As we are in close touch with our mare’s dam’s breeder, we feel like we have a good handle on our side of the equation. Jaguar Mail’s sire and dam are also very known quantities so all that can be done now is to wait. In the meantime, we can look to the pedigree with some hope, as it contains many names that were both good producers and performers.[/QUOTE]

Thanks. Not that there is any reason you shouldn’t have answered politely. :slight_smile: People tend to read too much emotion into replies on bulletin boards.

#94

I have a gelding who has one grandsire. Obviously, this is a different situation than the one you’re contemplating because I have no intention of breeding him. But my experiences with him might be helpful. I can tell you that he has ALL of the wonderful traits of his grandsire. And, in fact, he is the spitting image of him, complete with identical markings! He has his grandsire’s classic good looks, suspended, expressive movement, HUGE, rhythmic canter and scope galore. His temperament is exactly what I would have expected had we gelded his grandsire.
On the other hand, he has all of his grandsire’s drawbacks as well. Granddad was a MANLY stallion, gelding is quite the stud, himself. He can be a handful, overbearing, likes to challenge weakness, has a temper…like I said, he’s JUST like his grandsire, who was by NO means an amateur’s horse, under saddle or on the ground. Fortunately, I loved his grandsire very much and I love everything about my boy, including his quirks, but do your research. If you know the grandsire, be prepared for a female version. If you don’t, find out whatever you can about him before proceeding. Best of luck either way!

#95

Oh, I do want to add that my gelding is a violent vaccine reactor, has hay fever-type allergies and suffers seasonal gutteral pouch tympany. He is also the only adult horse on the farm that gets the fall and spring “snotties” when the babies do. I fully attribute his wonky immune system to his inbreeding. He’s improved with age, but he definitely requires careful management that I don’t think he would if he’d benefitted from more genetic diversity.

#96

[QUOTE=DownYonder;7202450]
Yes, I know that. But thanks for the insult - I am one of those “brainless spreadsheet sorts” who finds it really aggravating that people change the names of BREEDING HORSES to aggrandize their own egos.[/QUOTE]

Whoops!!! (But horses are all about aggrandizing egos! That’s what horses do! :D)

#97

FWIW, I have a BS in zoology and took courses is genetics including molecular genetics and population genetics and have continued to read on those topics over the years so I do grok your point and happily concede that the simple Mendelian model of inheritance is neither fully accurate nor precise. :slight_smile:

My point on correcting GAP’s misstatement on the [approximate] inheritance pattern of the recessive mutations associated with disorders like CA, SCID, LFS, HERDA, and LWO was that it is not uncommon to see incorrect statements of the statistical outcome of mating carrier individuals to clear individuals in regards to using these screening tests. This is a common mistake/misstatement that I did not want to see perpetuated.

#98

[QUOTE=Dawn J-L;7202566]
FWIW, I have a BS in zoology and took courses is genetics including molecular genetics and population genetics and have continued to read on those topics over the years so I do grok your point and happily concede that the simple Mendelian model of inheritance is neither fully accurate nor precise. :slight_smile:

My point on correcting GAP’s misstatement on the [approximate] inheritance pattern of the recessive mutations associated with disorders like CA, SCID, LFS, HERDA, and LWO was that it is not uncommon to see incorrect statements of the statistical outcome of mating carrier individuals to clear individuals in regards to using these screening tests. This is a common mistake/misstatement that I did not want to see perpetuated.[/QUOTE]

Thanks Dawn, for correcting my mis-statement. I have a BS in Biology as well. The 1:2:1 ratio for the cross of two heterozygotes was correct.

"It serves little point to discuss this inheritance in terms of 25/50/25, because we know that this is not accurate (even if there was Mendelian inheritance there would always be recombination). "

Surely, Stoney, you do not mean that Mendelian inheritance never applies? As I said, for genes that are not on the same chromosome or closely linked, MI usually does apply.

#99

[QUOTE=grayarabpony;7202588]

Surely, Stoney, you do not mean that Mendelian inheritance never applies? As I said, for genes that are not on the same chromosome or closely linked, MI usually does apply.[/QUOTE]

No of course not, and aside from semantics I think that we closely agree with our attitudes towards line breeding in general. ETA: I think we are focusing on apples and oranges, because in re-reading Dawn was talking about specific diseases above, which may likely be inherited according to Mendelian models I havn’t looked at them specifically, whereas I am talking about how line breeding works as a whole in regards mainly to traits.

To clarify (hopefully) what I meant earlier:
If we want to talk about highly-penetrant genetic disease or a trait like eye color, then yes, it is likely that you can approximate with a Mendelian model and be highly accurate. However, the purpose of line breeding is not necessarily to breed for disease or lack of disease, but rather to amplify phenotypic traits in your breeding population. Most of these traits are not concretely defined by a single gene and therefore the pattern of inheritance may diverge from the Mendelian Ideal. I have done enough linkage analysis in my own research (as a post-doc at a well regarded University) to feel confident in saying that when looking at traits we will often find ourselves in the realm of partial penetrance and incomplete inheritance.

You cannot simply breed for a trait like a great neck according to the Mendelian model since we are talking about a trait made up of the influence of several genes which are linked either strongly or weakly, have varying levels of penetrance, and may or may not be inherited together. Line breeding is used to increase the homozygosity of the population, and through this to strengthen the linkage of the genes associated with “great neck” or some other trait (through increasing the chance that these genes will all be inherited together). Once this has been done, the penetrance will dictate the effect you will see once you breed outside blood into the population. The goal of outcrossing is to maintain the beneficial linkages establishing your desired trait while diminishing the liklihood of adverse linkages from being established in the population.

Then you have the general rinse and repeat over the generations that works to link traits together as well. This is the idea behind why Holstein has founded their breed on a specific few superior lines. They breed according to the lines, then bring in blood for a generation and then go strait back to their line breeding for subsequent generations in order to hopefully establish a linkage that embeds the traits they want in their breeding population. This is how they have linked traits together to establish the general “type” that they are so proud of.

For those that like links showing evidence (these are a select few, and may not be available outside of University. If anyone wants to read them, I will be happy to provide them directly, although I have to say they are highly science-oriented and all related to human health):

Outlines the application of Mendelian genetics versus non-Mendelian genetics (shows that GAP is correct about genes with high penetrance, but that it does not often apply):
http://www.nature.com/ng/journal/v33/n3s/pdf/ng1090.pdf

Outlines the fact that Mendelian inheritance patterns are important as “textbook examples” but “In most clinical genetics settings cases are seen where the disease diagnosed is well known to have a strong genetic component, and show some familial recurrence, but no clear Mendelian inheritance.” (Quote is from the text)
http://hmg.oxfordjournals.org/content/13/suppl_2/R225.full.pdf+html

Outlines that we have known that traits are not inherited according to a Mendelian model of genetics since the 1970s with examples on assessing traits and heritability (the example used is handedness in humans).
http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1977.tb41916.x/pdf

#100

Stoney you’re getting into the realm of expression of genes versus inheritance, which is another matter ON TOP OF Mendelian genetics and gene linkage.

Get your Digital Subscription here - only $21.95 / year

Subscribe here
See gift options

Sign up to our monthly newsletter!

By submitting your email, you agree to our Terms of Service and Privacy Policy. You may also receive promotional emails from The Chronicle of the Horse. You can opt out at any time.

Copyright © 2023 The Chronicle of the Horse