Outcrossing on Shetlands

[Boinky]

Hi John,

Thanks so much for answering questions! This is all very enlightening. I'm not sure if I can word this correctly hopefully it's not too confusing. I found it interesting in several of your posts that you had said that you had never seen dwarfism in purebred shetlands (and other pony breeds you mentioned). By outcrossing more with shetlands would this gradually reduce the carriers produced since that gene is not coming from one of the two parents each time? If you were to heavily out cross over several generations would you likely eliminate the dwarf gene in that line all together?

If so this "fad" (as many like to call it) of ASPC/AMHR horses could only be GOOD for our, lack of better words, "breed".

Thanks,

Hillary

 

[Arion Mgmt]

By introducing horses (ponies of any breed) with genetics that are not, you can gradually decrease the percentage of resulting carriers, but it would take quite sometime. For one you do not know which foals from the crosses are non-carriers and which are carriers, only breding and getting a dwarf would distinguish that. Using the ponies as outcrosses does not solve the problem short term or even long term genetically for well conformed desired horses that are still carriers of the recessive gene, because those individuals would still carry those genes on to their offspring and later generations. What was done decades ago in the Hereford and Angus cattle breeds was the carriers of the recessive dwarf gene were slaughtered as soon as they produced a dwarf. That very quickly removed a large portion of the dwarf gene carriers. Thereby it was pretty much erradicated by slaughter and got meat market money for the carriers rather than trying to find a common physical trait and solely basing the carriers on that trait, (this was before animal genetic research testing was common). We in the horse industry dont have that option at all.

So to answer your question as easy as possible, adding pony breeds to the gene pool will help dilute the number of carriers within our "breed" over the long term and make the dwarf genes less common within the gene pool therefore causing less dwarfs to be born. However it will not eradicate the dwarf genes from the total gene pool within our "breed".

John