Changes in the calculation of productive life evaluations
resulted in lowered proof values, especially for higher ranking genomic-proven
sires. An excellent writeup on this
change is available here!
In summary, genetic correlations used
in PL calculations were updated to more accurately reflect culling trends. The positive correlation with DPR increased
(as DPR increases, so does PL) as well as the negative correlations with SCS
and size composite (as SCS and body size increase, PL decreases). Correlations with UDC and FLC are still
positive (as UDC & FLC increase, PL increases) but not as strong.
AIPL looked at how these changes affected the
top 100 NM$ genomic-only sires and also the top 100 progeny-proven sires from
the August 2012 summary. December 2012
evaluations for these bulls revealed average decreases of .9 months of PL and
53NM$ for the genomic-only sires as well as a decrease of .4 months of PL and 25NM$
for the progeny-proven sires.
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