Black Angus - epd MARB to IMF% conversion???

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lms0229

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For the US Black Angus breed the epds have MARB scores, but places like Australia use IMF% (which to me makes more sense), but how do they correlate? For example, if here the MARB score is 1.26 what would that mean in IMF% terms??? I haven't been able to find anything out that looks straightforward. Thanks!
 

WB Angus

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Good question I would like to know the answer to that myself. Here in the states a few years back they gave a shear force score which in my understanding was a marbling and tenderness type score before the marbling epd of today
 

Nkline

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Marb epd in Angus is largely influenced by %imf ultrasound data, they take the estimated correlation of marbling and imf%, plus a little bit of actual carcass data (usually hardly any on a lot of cattle), and derive the marb epd. As a general rule around 9% imf is prime, but don’t quote me on that, and marbling “fleck” size matters, as large continuous flecks don’t count more towards carcass marbling score than a tiny fleck. You take total number of flecks per area to determine marbling score and in turn carcass grade.
 
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lms0229

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Marb epd in Angus is largely influenced by %imf ultrasound data, they take the estimated correlation of marbling and imf%, plus a little bit of actual carcass data (usually hardly any on a lot of cattle), and derive the marb epd. As a general rule around 9% imf is prime, but don’t quote me on that, and marbling “fleck” size matters, as large continuous flecks don’t count more towards carcass marbling score than a tiny fleck. You take total number of flecks per area to determine marbling score and in turn carcass grade.
What is the estimated correlation factor between marbling and imf%???

So just making sure I understand. They would take the imf% from their scanner and then multiply it by a standard correlation number? Would you mind doing an example for me? Thanks so much!
 

wbvs58

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You could look up a couple of US bulls used in Australia on the Angus Australia website and see what the relationship is between their Australian IMF value EBV is compared to their US marbling EPD. This is not a scan value but the expected difference above a base line.
eg. GAR Ashland

Ken
 
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lms0229

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You could look up a couple of US bulls used in Australia on the Angus Australia website and see what the relationship is between their Australian IMF value EBV is compared to their US marbling EPD. This is not a scan value but the expected difference above a base line.
eg. GAR Ashland

Ken
Ken thanks! This is perfect!

Why does the US choose a MARB score over IMF%???
 

Nkline

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What is the estimated correlation factor between marbling and imf%???

So just making sure I understand. They would take the imf% from their scanner and then multiply it by a standard correlation number? Would you mind doing an example for me? Thanks so much!
So it looks like the correlation the AAA lists for ultrasound imf% and marbling is 0.71 which is high. A correlation of 1.0 is perfect this would mean as imf goes up marbling score perfectly matches the up trajectory, at 0.71 as imf goes up marbling score very likely goes up but not necessarily matching imf based on different animals so pedigree info is brought in to massage the numbers. If a family usually has a better marbling score than their ultrasound imf indicates they will be biased up for marb epd.

Why does the AAA use marbling epd instead of imf, because marbling score is what is measured on the kill floor, and they can use it directly in the $ index values (generating hype).
 

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