Fixing Type

[Shammy Davis]

http://www.mitotyper.com/fixingthetype.html

[Dave C]

I think it deals with ideals rather than reality or at least recent reality. There aren't that many breeders now days that are doing multi-generational breedings; many of even the most accomplished mares will move through the auction rings a couple of times as broodmares. I also question what percentage of breeders ever really understood the concepts of linebreeding and inbreeding; most probably, like today, just bred to the best stallion that was available and hoped for the best.

[Nessa]

This is probably what is wrong with racehorses these days. They don't have a fixed type, too many are bred with the sales ring in mind and not fixing and reinforcing the qualities that the mares or stallions possess.

[Shammy Davis]

Nessa: I agree. I've been reading a book titled "Breeding to Win" by Michael Miller that was published in 1943 in the UK. He makes the same important point and actually discusses the breed for the commercial market mentality. It amazes me, as I read many of these dated books, that the same problems that we today see in the breed was recognized pre-WWI.

[Shammy Davis]

Nessa posted:

This is probably what is wrong with racehorses these days. They don't have a fixed type, . . .

You know I remembered your comment and I've been re-reading (for the um-teenth time) Franco Varola's TYPOLOGY OF THE RACEHORSE. On page 2, I came across this:

Of course, the Mendel theories do apply to the Thoroughbred, for the simple reason that his animal is a hybrid; but breeders have never been able to make them work, in the first place because the Thoroughbred is not produced with the intent of isolating a specific trait, but rather on the basis of racing ability. This means that the personal judgement of the horse's connections as to what the racing ability is, and sometimes the relations of which they dispose racing ability is, and sometimes of which they dispose on the commercial side of the bloodstock world, determine whether a certain horse or mare will have a reproductive career, and on which terms. . . the life span of a broodmare is too short to allow any significant testing of the Mendelian principles . . .

[Roger]

I don't think that fixing type is all that hard if one will consider 3 or 4 generations. Defining type is the problem because sprinters and stayers call have very similar body types. It really requires knowing what is in the first two removes of horse and breeding towards the type you want. Its done all the time in cows and other livestock. I've been told that dairy breeders have been able to increase milk volume and butter fat content. Thats like saying we've been able to breed a speed horse that can run two miles. Another problem with defining type is the fact that your classic horses for the most part could be outstanding sprinters.

[Linda_d]

I don't think that fixing type is all that hard if one will consider 3 or 4 generations. Defining type is the problem because sprinters and stayers call have very similar body types. It really requires knowing what is in the first two removes of horse and breeding towards the type you want. Its done all the time in cows and other livestock. I've been told that dairy breeders have been able to increase milk volume and butter fat content. Thats like saying we've been able to breed a speed horse that can run two miles. Another problem with defining type is the fact that your classic horses for the most part could be outstanding sprinters.

Robert Kleberg of the King Ranch in Texas did this with his Quarter Horses by continually inbreeding and then line-breeding to a horse called Old Sorrel (1916). By the 1960s, King Ranch Quarter Horses had a pretty well established type, even down to phenotype since most were sorrels (chestnuts) with few white markings.

I'm not sure if the King Ranch still continues to practice inbreeding/line-breeding today because they've added new bloodlines through stallions since the 1970s.

I think Kleberg used line-breeding in his TBs but I don't think that he ever employed the level of inbreeding in his TBs that he did with his Quarter Horses. I'm not sure why, except perhaps that he just never had a good enough TB stallion to build a program around. He might have also felt that perhaps there were too many variables in making a race horse versus making a ranch horse.

[xfactor fan]

My guess is that he didn't have the huge numbers of horses to work with that he did for the Quarter Horses. The ranch needed a large number of working cow horses so he was able to tightly linebreed/inbreed pull superior horses for the breeding program and put the "culls" to use as working ranch horses.

Same thing for his cattle breeding program, but in that case "culls" ended up at the supermarket.

I was reading that Robert Kleberg managed to secure two breeding to the great stallion Hyperion, toward the end of the stallions life. The best of the two foals was killed by a lightning strike, and the second died shortly after retiring from racing. Must have been a huge disappointment for Kleberg. One of those what if questions. If either of these foals had survived, what might Kleberg been able to do with the bloodline?

Given that Assault managed to get a few mares in foal toward the end of his life, I wonder why he didn't include a few TB mares in the band of mares running with Assault?

[Venusian]

Re Assault, was his original inability to get his mares in foal a libido/shyness or a sperm count/deformity problem?

How did he get to become fertile in his later years?

[Roger]

"I was reading that Robert Kleberg managed to secure two breeding to the great stallion Hyperion, toward the end of the stallions life. The best of the two foals was killed by a lightning strike, and the second died shortly after retiring from racing. Must have been a huge disappointment for Kleberg. One of those what if questions. If either of these foals had survived, what might Kleberg been able to do with the bloodline? "

The horse that lived was Zenith and he was a pretty good sire with one major winner. His name was Buffle. At the time the breed was saturated with Hyperion blood and it seems that the inbreedings to him were failures, its been a long time since I look at this stuff.

[Shammy Davis]

I'm no expert, but I've done some reading. Most recently I completed a couple of books on breeding by Michael Miller. Miller and Hislop agree that inbreeding has to come from the distaff side. Both suggest too much emphasis is placed on the sire.

For many years, I bred field trial and hunting quality Chesapeake Bay Retrievers (CBR). I used the female path to inbreed for blood renewal and as I often say, bring the "dead" athletes back to life. It was very successful. I must say though, you can only get away with inbreeding up to point. Culling is a difficult process and it is very inexact. There were a few litters that I had problems with and I had to dispose of them and re-evaluate my program. There comes a point that the breeder has to gamble on the benefits of outcrossing. It probably only takes one outcross, if the breeders judgement is spot on. The CBR and TB are hybrids so I don't think you are seeking hybrid vigor. I just think you offering up other traits to compliment the existing type that hopefully the breeder has fixed. Maybe, with outcrossing, you are actually diluting the gene pool so that over dominance does not become a detrimental factor in the offspring of a particular mating.

I am not the brightest candle on the cake, but experience tells me that when involved in breeding you have to look for genetic strengths but you must also seek environmental support. During the early period of a foal's life, the mare provides that. In the mare, we find the foundation for sustaining the TB. As breeders, IMO that we have look toward the family lines and use the inherently good traits as a map for future matings.

On Louis' inbreeding/unsoundness thread, he keeps saying that by outcrossing within TB lines you regain hybrid vigor, etc. Don't be fooled. Hybrid vigor is not an option when breeding two TBs. I think that within the TB their are different types and characteristics and because the mare population is so large that any idea of truly close inbreeding is an extremely distant challenge.

We have a small broodmare herd of 9 mares. Not one of them has Mr. P in them. Quantitatively, anyone, like Louis, who believes that the industry is on the verge of breeding siblings to siblings or sire to daughter, etc. is out of touch w/the realities of how many TBs there are in this world. IMO of the opinion that gene pool is relatively safe and what Louis and others are calling inbreeding is just linebreeding.

[Roger]

"On Louis' inbreeding/unsoundness thread, he keeps saying that by outcrossing within TB lines you regain hybrid vigor, etc. Don't be fooled. Hybrid vigor is not an option when breeding two TBs. I think that within the TB their are different types and characteristics and because the mare population is so large that any idea of truly close inbreeding is an extremely distant challenge. "

When you think of hybrid vigor, I think you have to consider gene pairs in the heterzygous (sp) state. Then take horses that I call inbred to traits and you can get hybrid vigor. A horse whose sire and dam are speed bred and cross it with a horse whose sire and dam are distance bred and you can get some hybrid vigor. If you do body types and speed to body types and distance, you get more hybrid vigor.
In the past there was a good theory about achieving hybrid vigor from breeding to horses in other parts of the world even when they had similar pedigrees. I think it was called environmental hybrid vigor. I think hybrid vigor results when two inbred "in the first 3 removes" horses are mated together. the old inbreed and out cross idea.

[Shammy Davis]

Roger posted:

. . . I think hybrid vigor results when two inbred "in the first 3 removes" horses are mated together. the old inbreed and out cross idea.

You know I think the literature on this subject is very confusing. I understand what hybrid is. I understand how the term "vigor or vigour" is used. What I have trouble grasping, and maybe someone can help me, is the concept of "hybrid vigor."

Hybrid vigor is a result. It occurs when the offspring is an improvement over the parents. The use of the word "parents" in this context, I believe to mean "both parents are purebreds but each parent is from a different breed."

I'm either confused or not confused, but I believe hybrid vigor is only attained by the underlined above.

Louis is using it in his thread as result of mating two TB's of the same breed which already happens to be hybrid. I don't think hybrid vigor is a result of such a mating. I think the original foundation breedings was when hybrid vigor was attained. The pertinent question when dealing w/the TB is over-dominance or dominance.

I think this is important issue.

The Thoroughbred's athleticism and stature has not dramatically changed in over 150 years. Some of the records have only been improved upon by fractions of seconds. Some records have stood for at least 50 years. The size of the TB has for the most part been static with very few samples in the 17 plus range.

Within the context of the Inbreeding/Soundness thread I think it is disingenious for Louis to suggest a result that is not/may not be available. I don't believe hybrid vigor is the result of breeding a sire and dam who are hybrids, like the TB. I think they have to be two different purebred breeds, like Black Angus and Hereford in the bovine world.

Xfactor Fan suggested to me that Haun was not a good science writer. I agree. I do now see the Xfactor path, but as with everything to do with genetic science you have to change your way of thinking.

My canine experience says to me that Roger is right. I think 3 removes is optimal for inbreeding and then you've got outcross.

[Roger]

The term hybrid is used when crossing two breeds, or when individuals within a breed with different traits are crossed. The old monohybrid cross of Tall peas and short peas is an example of hybrid traits (TT, Tt, tt) Tt is the hybrid. Individuals from different species are also called hybrids ie. mules. Hybrid vigor is nothing more than those positives that occur when two inbred animals or plants with different genes for the same trait are crossed. They tend to be stronger, more fertile and over all more healthy than their inbred parents. In horses we get away from the idea that traits can be bred to and we sometimes start looking at names in pedigrees without thinking about the traits those names represent.

[Shammy Davis]

"the detection of an existing species or subspecies as a new [i.e., as a nonintermediate] derivative of past hybridization is well-nigh impossible, since by definition such new types would not be recognizably intermediate between their parental species."

http://www.macroevolution.net/heterosis.html

In reply to Roger's last post, my point is that breeding Thoroughbreds with different pedigrees does qualify as an opportunity for heterosis or hybrid vigor. The definition of inbred is difficult at best to ascertain so I won't even go there.