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 Heterosis/Prepotency/IBCs

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Grassfarmer



Posts : 850
Join date : 2010-09-27
Location : Belmont, Manitoba, Canada

PostSubject: Heterosis/Prepotency/IBCs   Tue Jun 05, 2012 6:51 pm

I was spending some time playing with the Kintraks program the other night looking at IBC scores and I came away further confused. My breeding program is basically closebreeding the descendants of the best animal I had in an attempt to reduce variation and reproduce more of the original animals type. I have quite a few animals now with 10-20% IBC scores, achieved by breeding closer to but not exceeding the "50% of one animals blood" theory. Very quickly my calves will all be similarly bred, although this is only on paper - there has been no selection or culling to date other than basic functionality.
So as we have a coming together of common ancestory it starts to look like this: <
The parent stock I've used generally have low IBC scores - indeed my best cow had a score of just about exactly 0%. This appears artificially low because what happened was the blending together at that period of time of two different, closebred strains of cattle - the Scottish Luing and the Canadian Snowlanders. Because of our small genepool I was able to do some close matings and get 16+% IBC scores in the first generation of offspring. On the Luing side many of the parent stock I started with are only 10-15 generations removed from the foundation of the breed from crossbred stock. But if you go back and work out the animals in those early generations of the breed they mostly had 15-20% IBC scores. We don't have records on the Snowlanders but they were likely similar. So in terms of close breeding and shared ancestory it looks like the < pattern we are breeding now is inverse but almost equal to the closeness > the breed started from. I guess this level of closebreeding is to be expected in the foundation of a new breed or strain of cattle as it would be the only way to fix a type? I guess every breed/strain would start from the same small base and depending how many generations and how much outcross breeding happens the > just keeps getting bigger and bigger. Maybe eventually a breed could get to a l and then you have to start over and select for a type or strain?

My question though is how does this affect the level of heterosis in the cattle I have given their two divergant parent stock breeds. People have suggested on here that because our breed is so young with so few generations under it's belt and from mixed breed ancestory that the heterosis must be at a high level. I didn't argue with that but have always been pleasantly impressed with the apparent prepotency of any of the bulls we have used. So how do heterosis, prepotancy and IBC scores inter-relate in this situation??

Man, that was confusing to write - hope you understand what I'm asking Smile
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MKeeney
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PostSubject: Re: Heterosis/Prepotency/IBCs   Tue Jun 05, 2012 9:30 pm

was I one that said heterosis would still be high? If so, I`ve changed my mind Smile
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Grassfarmer



Posts : 850
Join date : 2010-09-27
Location : Belmont, Manitoba, Canada

PostSubject: Re: Heterosis/Prepotency/IBCs   Tue Jun 05, 2012 10:22 pm

MKeeney wrote:
was I one that said heterosis would still be high? If so, I`ve changed my mind Smile

Don't remember if anyone actually said it - it was just the impression I got - and I started to wonder about it myself after reading how many generations of cattle it takes to establish a type or strain. So do a pattern of higher IBC scores automatically indicate reduced heterosis?
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Grassfarmer



Posts : 850
Join date : 2010-09-27
Location : Belmont, Manitoba, Canada

PostSubject: Re: Heterosis/Prepotency/IBCs   Sun May 05, 2013 12:41 am

Does anyone know what the IBC scores on the Lents herefords are like? Is there a way to access that information on-line - through Hereford Association or should I contact the man himself?
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MKeeney
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PostSubject: Re: Heterosis/Prepotency/IBCs   Sun May 05, 2013 8:01 am

Iain,
there was a university research study Jim used to tout that showed his cattle inbreeding intensity considerably greater when compared to the Hereford breed and compared to Line 1...it was not just a pedigree analysis, but was before the day of genome mapping...might have been blood groups etc...call or email Jim; you`ll enjoy the conversation...
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Kent Powell



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Join date : 2010-09-24
Location : SW Kansas

PostSubject: Re: Heterosis/Prepotency/IBCs   Sun May 05, 2013 8:47 am

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Grassfarmer



Posts : 850
Join date : 2010-09-27
Location : Belmont, Manitoba, Canada

PostSubject: Re: Heterosis/Prepotency/IBCs   Sun May 05, 2013 9:43 am

Thanks Kent. I'll maybe do that Mike.
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