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[RC] Selecting for longevity in endurance competition - k s swigartEd said: You could singlemindedly select for horses that could run 100 miles in 24 hours from the time they were 5 until they had 10,000 miles of competition. You then, 200 years later, would have great endurance horses. Actually, you would have a hard time in actually selecting for the ability to do 10,000 miles of competition starting when they are 5 specifically, since by the time that you had proven that the horse can do it (thereby proving its ability for this)...and can throw horses that do it (therefore proving not only that the horse can do it but that the trait breeds on), the horse is dead. One of the essential requirements for "singlemindedly selecting for" a particular trait is that you must ruthlessly crop out those that do not exhibit the trait, and you must also ruthlessly crop them out if, even if the horse does exhibit the trait, its offspring don't. Consequently, you it is extremely difficult to select for a trait that doesn't exhibit itself until after the individual's breeding career is already over. You would have to find some other way to performance test the individuals (and its offspring) that you hope is a good proxy for the ability to do 10,000 miles of competition starting when they are 5. Some people say that being a war horse in the desert is a good proxy for this, some people say that the feral lifestyle of the western US is a good proxy for this, some people say that flat track sprint racing is a good proxy for this, and some people say that working cattle on the Rushcreek Ranch is a good proxy for this :). However, the fact remains, that all these things are but proxies to be used as selection criteria because the real trait that is being hoped for would take 30 years of testing to find out which horses you should have been breeding (before they died :)), especially since so far virtually all the horses that have successfully proven that they can do this are.....geldings (i.e. genetic dead ends :)). It is virtually impossible to "singlemindedly" select for longevity in endurance competition, instead what breeders must do is select for other traits that they hope will lead to longevity in endurance competition. Some of the new reproductive technologies (frozen semen, embryo transfer, etc.) may extend an individual horse's breeding years to the extent that it may become easier in the future. However, in order for it to be done with any real hope of success, it also has to be done LOTS. kat Orange County, Calif. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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