Depth of Inbreeding

[dray33]

I know it has been asked before, but how do some of the pedigree experts/breeders on the forum know when "close" is "too-close"?

I was looking at breeding to a mare. Sometimes, the resulting mating would yeild a 3x4 to Seattle Slew. Too much? I know Broad Brush was 3x3 to Turn To. Can anyone offer some rules, how do they analyze the closeness factor in breeding?

Thanks...

[madelyn]

When it works, it's linebreeding and everyone jumps on it.. when it doesn't, it's "too close"

But seriously. Sometimes there can be no inbreeding, per se, in a horse's pedigree (5 generations) but, being "all one herd" there is if you follow the lines all the way back. Whatever you choose to do, inbreed 3x3, 4x4, etc., guaranteed if you get a good stakes winner folks will rush to follow.

[dray33]

Understood... but how do you decide? 3x3 is fine for some, too close for others. Why?

[louis finochio]

Lets say you would considering a mating of 3X3 to Nasrullah. By mating those two individuals you would double up the hot and nervous energy of Nasrullah in the offspring. Better to mate a calm individual with a nervous one to breed out the bad temperment.

When you are inbreeding to close the offspring of those matings will have many conformation faults, such a thin bone spindle legs that cannot support the weight of a Tb.

When a breeder seeks an outcross, those spindle legs will be replaced with good strong bone in their underpining.

[Georgerz]

Louis:
What kind of data do you have to back up your assertions? Otherwise, this is nothing more than wild, worthless speculation.

[louis finochio]

Common sense is where I get my knowledge of making the union of 2 nervous high strung individuals.

[bcassidy]

Some of the best individuals in any species occur as a result of inbreeding and it should only be done using the finest specimens available. You certainly wouldn't want to inbreed to an individual of poor quality.
If we look at the species of dogs, many of the breeds recognized by the AKC started as a result of inbreeding to a particular individual with a certain desirable trait that the breeder was trying to permanently imprint into that breed. After that trait or traits was capable of reproducing itself for many generations, then the AKC would recognize that breed as a distinct breed--- Sometimes that breed was the result of one unique individual or many times the result of several unique crossings.
therefore, I conclude that the closely inbred animal is by far the best animal to breed because the concentration of genes in an inbred animal yield the most consistent result in their offspring.
As an example, mating one stray dog to another stray dog could produce just about any type of offspring, while mating one pure bred animal to another pure bred animal of the same species will always produce a similar type of offspring----breeds of dogs are nothing more than selective inbreeding.
There are certainly many disadvantages to inbreeding because you not only get a concentration of the desirable traits you are trying to concentrate but quite often you can get a concentration of undesirable traits as well, so inbreeding can be very successful or more often very disastrous.
Another undesirable outcome of inbreeding is generally referred to as loss of vigor, sometimes as the concentration of genes through inbreeding increases---- overall wellbeing is compromised to the point that the offspring generally loses its overall wellness.
In such cases, breeding that animal to another animal of different concentrations (an outcrossed individual--- as an example or another individual closely inbred but to a different individual than the other parent) can often produce an exceptional animal---- often referred to as having hybrid vigor---these individuals can almost display superhorse type characteristics. .
I subscribe to the theory that we are all much better off when we start with animals that have a high probability of producing the same traits in their offspring (usually found in linebred or inbred animals) because mating two individuals of totally different backgrounds results in totally unknown outcomes---in other words---it's a total crap shoot.
Genetics is a very complicated field and I certainly couldn't go toe to toe with an up to date geneticist but I do know enough about the science to be conversational about it and I love to read about it ----but I am also quite confident---- that no person alive today totally understands the exact science of genetics. We are still years away from having mastered this field and in a lot of ways this makes the topic so much more interesting----we don't have all the answers today--so it leaves room for non experts like me, ha ha.

[bcassidy]

Dray-I reread my post and realized I didn't answer your question. No one knows how close is too close and it would vary depending on the individual in question. (some individuals are more closely inbred than others---so using one animal vs another would yield totally different results)
In general, inbreeding is very desirable when it yields great results, but the results are not always predicable and when it doesn't work it is quite disastrous, so the rewards are great but the risk is equally great.
Also breeding an inbred parent is much more consistent than using an outcrossed parent, as the concentration of traits is more easily reproduced in the inbred animal--making it more consistent.
I hope that helps---it is difficult to discuss this topic without getting too detailed or too wordy.

[louis finochio]

I am not against in-breeding but when it has been carried to far, the red flag warning will be rasied when a Tb breeder will notice the following.

Has the fire gone out of your Tb eyes, has the racing performance slipped to a lower level, are your Tb underpining starting to resemble a spindle leg appearance.

Do the heads of your colts look like filly's instead of colts? Do your Tb go off their feed after a hard work or race. Does your Tb take longer than normal to bounce back after coming out of a hard race.

Is the soundness in your Tb family starting to decline? Your Tb are telling you its past due time for an outcross.

[louis finochio]

Many years ago the Arabian Breeders were breeding their arabian horses to close. Those breeders were breeding Arabian horses that were getting smaller and smaller with a frail constution, as a result of too close inbreeding.

Many Arabian breeders were gelding their stallions to try and halt the close inbreeding that was taking its toll on their horses.

What those Arabian did to stop the decline in their horses was to import those Arabian horses from foreign countries that were an outcross from their bloodlines and that was the answer to breeding back the hybrid vigor and stout conformation that was a product of their original Arabian foundation stallions and mares.

[jagger]

Many good points have been made by Louis, Brendan and others on this thread and I would just like follow up on some of their thoughts. Inbreeding has been very successful in many forms as mentioned by bcassidy - dogs for instance. Cattle, hogs, sheep, chickens, corn, beans, alfalfa. The goal in all these inbreedings is to eliminate the negative traits and augment the positive traits. Corn can be made that requires less water and matures faster and is resistant to many diseases. Cattle can be inbred to produce an animal that requires less feed and grows faster than their ancestors. The difference between inbreeding thoroughbreds and all these other applications is that with cattle, hogs, sheep, corn and beans, we cull the miscreants. If the corn or chicken does not display the desired traits, they are not permitted to procreate. With thoroughbreds, if you spend 100k on a mare and 25k on a stud fee and another 20k to 40K on various costs and the resultant foal runs poorly, not at all or breaks down early in it's second year, the owner still wants to recoup their investment somehow and so a significantly flawed stallion is allowed to perpetuate these flaws and brings several hundred more flawed animals into the gene pool. How many times have we heard something to the effect of, "be sure you mare has good front legs if you take her to stallion A as he is severely "over at the knee". HELLO. We are talking about animals that are supposed to run fast and it would seem appropriate that any animals that we permit to breed, should have good LEGS!! If an inbed strain of corn seed required just 1 more additional month to mature, it would surely not be used ever again and this flaw would not be passed on. This is ONE of the reasons that we have horses like Louis has described above, with spindly legs who break down early in their careers and yet are standing at famous barns in Kentucky, Florida, California, Pennsylvania and so on.

Can a good horse result from inbreeding? Sure. Obviously. If it is my money, I would NEVER attempt an inbreeding unless the proposed inbreeding had proven successful in the past. To embellish bcassidy's good point mentioned above, the conduits in an inbreeding are more important than the inbred horse himself. For instance. Mr. Prospector is arguably one of the top sires ever and will be atop the general and broodmare sire lists for many years to come. He has many very successful sons, grandsons, great grandsons. It is impossible to know how many times a Mr. P inbreeding has been attempted but the number is probably in the thousands if not more. Yet, he has had roughly only 60 horses who have won a graded stakes race when inbred. Further, despite all his very successful sons, only a very few have been successful as conduits. Fappiano is by far the most successful - appearing in 18 or 19 of these 60 horses. So, if I had a mare with Mr. P in her pedigree who had never appeared in any of these 60 successful inbreedings, I would certainly not take her to a stallion whose conduit to Mr. P had not been successful as well. If the conduits to Mr. P on both sides were daughters, this also would be foolhardy as only 1 or maybe 2 of the 60 horses were inbred through 2 daughters. If I had a Fappiano mare, however, I would have no misgivings taking her to a Seeking the Gold line stallion.

I am fairly sure that <5 horses inbred to Seattle Slew have won a graded stakes race - to answer the original question.

Hope this helps.

[Isanti]

Brendan, you hit the nail on the head using the dog comparison. It's the same in horses, except for one small, yet harsh truth. A mare will only foal one foal, a bitch will whelp a litter. Within that litter is what the breeder chooses for show or companion. A foal, well, that is it my friend, until you get her in foal again.

My advice is to research the horses in question, not only the horse your linebreeding off of, but the offspring you will be using to perform the linebreeding, i.e. the son(s) and/or daughter(s), and see what unsoundnesses they have produced, and always be sure to compliment thier superior traits as well. In line breeding you really have to know the genotype, and where it's headed. I would also pay attention to phenotype of the individuals in question, it may help make some decisions as to what individuals you want to use to perform a linebreeding.

[bcassidy]

Louis/Jagger, I think there are many examples of inbred animals that have been exceptional either as runners or producers, who's to say because an animal didn't run well, it is totally the fault of the animal. Cleary humans and good fortune play a role in either a poor performer or even the exceptional performer. Who knows how Unforgettable Max might have performed in Matz's barn or Afleet Alex in Perkins barn? We will never know the answer to these type of questions.
Jagger, does goldmine look only at inbreeding on the male side of the pedigree? I am a big believer in inbreeding to the dam's side of the stallion pedigree. As you and I have discussed in print in the past, you have to be very careful with the raw data, you really have to know what questions to ask. Just as in the nicking data from Jack Werk or Dosage analysis, the devil is in the details. I am very curious if goldmine can analyze inbreeding on the female side of both the stallion and the dam.
Isanti, great point and I use this next example to make a point about the exact issue you raise. Bonnie's Poker was mated to Silver Buck four times----she produced Silver Charm only once. How do you rate this mating? Was it successful? Would you have stuck with the mating for four foals? Was Silver Charm a crap shoot?---that one in a million horse that could occur from just about any breeding if all the best genes line up in a specific individual? Were the other three foals handled differently? Did misfortune play a bad note for one of the other three foals?
These are great questions and unfortunately we will never know the answers to most of them.

So what conclusions do you draw from any of the issues raised above? I am not willing to give up on inbreeding merely because it has many risks associated with it. I think the best animal one can produce (especially one that will be a great producer) will be the inbred animal.
Waiting for lightning to strike, which can happen at any mating, is not a sound breeding strategy for me. Too many "so so" animals will be produced before the exceptional animal is produced. Just my thoughts--very curious to hear what others think on this subject.

[jagger]

Brendan,

Agree 100% with the above. I am NOT opposed to inbreeding and apologize if it seemed as so. I am unwilling to be the "guinea pig" and attempt any breeding whether inbred or outcross unless it has shown success in the past. If others want to, that's fine. Unless someone has "sheik" like cash, it seems imprudent to attempt any mating that has not had historical success. JMHO. Or to use the Goldmine analogy, if you were given 1 year to produce 1 pound of gold or you would be castrated (we need the castration part for incentive) would you be more likely to dig for gold in Vermont and Indiana or California and Alaska?

Yes, Goldmine can do any combination - male to male, female to female or female to male. Michael Ventura does admit, though, that the data is skewed when coming up with a VGS score for an inbred horse.

[bcassidy]

Jagger, so how would it reconcile an inbreeding to both the stallion's top side and bottom side simultaneously?
example----stallion is a son of Mr P, dam of stallion is a daughter of Danzig, which in turn is a son of Northern Dancer. Mare is a daughter of a son of Mr P and the second dam is a daughter of Saddler's Wells, which is a son of Northern Dancer.
Curious who would get the blame for a bad mating or the credit for a good mating in the example above. This is just one small example of what I mean about the devil is in the details.
As always I appreciate your input.