Management
sold. Selling bulls with genomically enhanced
EPDs is a standard practice to ensure that when a
young bull is sold to a commercial rancher, he will
perform as expected. In other words, purchasing
a heifer bull will not lead to a calving season filled
with pulling calves. Genomic testing increases
the confidence a seedstock producer has in the
bulls they are selling, as well as the confidence
the commercial customer has in their purchase.
Why the increase in accuracy? Due to basic biology,
officially termed Mendelian sampling, there are
over one quintillion possible combinations of
DNA that full sibling calves can inherit, no matter
the sire. Traditionally it has taken several years of
recording phenotypes of progeny to characterize
which calves inherited the “good” genes from their
parents. Genomic testing is a tool to characterize
what specific genetic merit an animal inherited
at a younger age than has been feasible from
pedigree information and progeny records alone
(Figure 1). Using the graph, comparing the curved
lines (Non-genotyped animals) to the straight
(Genotyped animals) for stayability (STAY) shows
that a very young calf can have a genomic test
which provides insight on inheritance of genes
equivalent to 25 progeny records based on where
the lines intersect, with an accuracy of 0.26. Think
about this - How old would a bull have to be to
have 25 daughters with stayability to 6 years
of age to calculate his stayability EPD from a
traditional pedigree based genetic evaluation?
Figure 1. Average BIF accuracies of GE-EPDs of DNA tested young animals (born in 2016 with no progeny) compared to non-genotyped sires
with progeny (born 2010-2014) in multi-breed genetic evaluation (Adapted from Saatchi et al. [2018] Iowa State Animal Industry Report
ASL R3227). The red square highlights the intersection of accuracies of genotyped and non-genotyped for stayability.
LIMOUSIN Today | 87