Two important scientific papers

[brogers]

Two really important scientific papers were published today (at least I think they are!).

The first was a paper written by Matthew Binns to do with inbreeding in the thoroughbred. He and his team found (unsurprisingly) that the thoroughbred has increased in inbreeding coefficient in the last 40 years, and even more so since the advent of big stallion books. The papers is really quite eye opening as it outlines the rate of inbreeding and how with the advent of big books, the rate has increased exponentially. The Thoroughbred is an inbred horse as it is, and of course increased inbreeding has been found to have a negative effect on overall population fitness. Binns made no assertions what the level of inbreeding may cause. I am sure that someone will grab on this paper and say that this is the reason we are having more breakdowns in thoroughbreds, or some other theory, but the paper doesn't make that assertion. It actually states that we don't have the data to support something like that at this time.

Importantly, this result is based on inbreeding coefficients determined from the genetic variation present at the DNA level in these horses and not from coefficients calculated on the basis of written pedigrees. We can't see how more inbred horses are becoming just looking at the pedigree page. This paper can be found here http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract

The second paper is on OCD's in thoroughbreds. The discuss the finding of a QTL, or location on the genome, on Chromosome 3 that may have SNP's (changes in the gene code) associated with prevalence of OCD's in thoroughbreds. They do say that their findings need to be independently verified by another source. This is the first paper I have seen on OCD's in thoroughbreds and its genetic cause (there have been papers on other breeds). This paper can be found here http://www.springerlink.com/content/07341964128pp8u2/ It is going to be really interesting to see how the industry at large reacts when geneticists start finding the variants that cause diseases like OCD's. Are breeders going to make an effort to select away from these types of things (presuming in doing so they don't also select away from speed!)

[Elles]

Can OCD be associated with inbreeding?

[vineyridge]

Shammy Davis posted a New Zealand researcher's presentation at a TB meeting that said pretty much the same thing as the Binns paper, although the New Zealand author's research was more statistical and concerned stallion books. More breeders in Australia use shuttle stallions than native born ones, IIRC the paper correctly. The shuttle stallion books are bigger, and the native lines are dying on top.

It's interesting that genetic study and the statistical one mesh so nicely.

So do we blame Coolmore and others like them for the distressing increase in levels of inbreeding? How can Coolmore stand what is essentially a 60% Danzig group of stallions? The other 40% are Sadler's Wells. They are just about 100% Northern Dancer. Vinny Roe may be their only non-ND stallion, and he isn't supported very well. Coolmore is also among the very biggest shuttlers.

[Shammy Davis]

Brogers wrote:

. . . He and his team found (unsurprisingly) that the thoroughbred has increased in inbreeding coefficient in the last 40 years, and even more so since the advent of big stallion books. The papers is really quite eye opening as it outlines the rate of inbreeding and how with the advent of big books, the rate has increased exponentially. The Thoroughbred is an inbred horse as it is, and of course increased inbreeding has been found to have a negative effect on overall population fitness. . . .

I think that the shuttle stallion program in Australia is positive, but it is only a stop gap measure until the global TB and horseracing industry decides to reform its sales and marketing methods. Large stallion books and select marketing are just a couple of the problems facing the NA TB industry. I've noticed over the years that Aussie horseracing periodicals have focused the physical state of the TB. Their articles are comprehensive and very informative and they leave me with impression that an "informed" Pacific/Asian fan base is their objective.

Education is the key, particularly when trying to lure more owners into horseracing.

I'm not very good at understanding this "genetic science" stuff, but I can understand enough to make some sense of it. JMO, but I don't think "inbreeding" has the negative effect that is currently being discussed. Having bred hunting retrievers for over 40 years, I know that good linebreeding (inbreeding is really not the correct term) breeding management and culling promotes a physically stable and instinctive breed. To increase good broad spectrum breeding programs and promote the stamina end of the TB, it is time that JC, NTRA, BC, et al start promoting longer races and also promoting "chasers" by insisting that a good portion of all race cards contain 12f and above competition. The racing public is not going to be upset. The high end stallion owners will not be happy with this approach because this requires that they approach the business with an eye toward supporting a healthy racehorse population and not a healthy bank account.

[Shammy Davis]

Elles wrote:

Can OCD be associated with inbreeding?

Currently OCD is referred to as "developmental" which suggests abnormal physical maturation. I would not be surprised that sometime in the not so distant future that the " equine genome studies" identifies some connection.

http://equineextension.colostate.edu/fi ... Priest.pdf

On the above pdf, there are a couple of links to KER studies. KY Equine Research is a valuable site. It will answer many of your questions. You should go there.