Have A Very Inbred Christmas

[Patuxet]

Some interesting observations on inbreeding which in turn prompted some interesting comments.

http://fmitchell07.wordpress.com/2012/1 ... christmas/

This in particular caught my attention and gave me pause:

"The late maturation of bone in the Raise a Native sire lines must be taken into account and accepted when inbreeding to this sire. One of the main reasons for the so-called unsoundness of this strain is that mentally and physically the young horses from this sire line mature very early, but their bones mature much later. The end result is that many 2-year-olds with a great deal of speed are allowed to self-destruct as their bones are not yet ready to withstand the stress of racing or even fast gallops or breezes."

[louis finochio]

RAN progeny have a pounding action, that accounts for many of their unsoundness. When RAN was bred to those NP mares, they had lifetime starts of, 136 Teddy mare, 50 Rock Sand mare, 40 Alibhai mare, 46 starts Double Jay mare, 76 starts My Babu mare.

If RAN was bred to those FB mares in the present, there would be widespread unsoundness.

[zinn21]

This is getting a bit ridiculous. The article Patuxet quotes alleges RAN line's bone mature late. Where is that scientifically documented?? And Louis with a "pounding action" by RAN line horses. There is absolutely no data on any line regarding running action. If both previous mentioned are "observations" it is, IMO, preposterous..

[valjoe]

There is absolutely no data on any line regarding running action.

Now there is .. if Luis said so

[Pan Zareta]

This is getting a bit ridiculous. The article Patuxet quotes alleges RAN line's bone mature late. Where is that scientifically documented?? And Louis with a "pounding action" by RAN line horses. There is absolutely no data on any line regarding running action. If both previous mentioned are "observations" it is, IMO, preposterous..

Further to the above, the article specifically states that late maturing bone is a characteristic of the Raise A Native sire line. The only factor constant to all members of a sire line is the tiny Y chromosome which is utterly lacking in diversity within the domestic horse. They're all the same. "Sire line" is a meaningless abstraction in terms of anything other than classification and sentiment.

What has been scientifically documented (McGivney et al. 2012, Bower et al. 2012) is a marked increase in frequency among TBs within the past 50-75 years of a 'mutant' (newer) allele in the myostatin gene complex on chromosome 18. Myostatin has a negative (inhibiting) effect on muscle mass. The newer allele exerts less inhibition than the wild type allele. In terms of muscle mass, a horse with even one copy of the newer allele will respond faster to exercise, with corresponding increase in weight. If there has been any commensurate increase in rate of bone growth no evidence for it has been presented in publication. When evaluating genetic factors that might be coming into play in regard to 'self-destructing' 2yos I'd say these facts merit consideration.

[Patuxet]

zinn21 wrote: "There is absolutely no data on any line regarding running action."

When you come right down to it I know of no scientific data proving that sire lines are responsible for any specific genetic traits.

As another poster aptly put it:

"The direct sireline is probably on average the LEAST influential line of inheritance, because while there are a number of traits sited on the X chromosome, the Y is pretty much devoted to turning a female (the default) into a fully functioning male. All other chromosomes are as likely to come from any horse in the same generation as they are from the tail-male ancestor."

[louis finochio]

A stallion will stamp his foals to a higher degree, than his mares. As those stallions progeny will look more like the stallions in conformation than his mares.

It will not happen 100 % of the time, as some mares are more dominant than recessive, as they will over ride the stallion.