Jones et al.: Value of Bull Characteristics
327
Figure 2. Predicted Premiums for Adjusted Yearling Weight and Yearling-Weight EPD
genetic information in birthepd relative to
birthwt, it appears they are unwilling to do
so for yearepd.
Reasons for the difference in these results
are not entirely clear. A possible explanation
may lie in the accuracy of the EPDs at the time
of sale. Bulls are typically sold at 1 year of age
or older. Buyers may believe that the yearepd
values for yearling bulls are in fact unreliable.
Because yearepd is based solely on records of
related animals (parents, grandparents, and
siblings), they may believe that the possible
variation in the EPD is quite large and thus
place more confidence in the actual weight.
Table 6 shows expected changes in the value
for EPDs over a two-standard-deviation range
as the accuracy of the EPDs increases. The
expected accuracy value for yearepd on a year
old bull would likely be 0.05. At this level, the
possible range of change for this variable
would be 616.17 pounds from the current
value of the EPD. This represents a large
change and gives cause for buyers paying
larger premiums for adjyearwt, an observable
trait. Another possible explanation is that
actual yearling weight is nearly observable at
the time of sale (i.e., the bull is either heavy or
not), whereas birthepd is perceived as the
better indicator of birth weight of offspring.
Model Including Carcass Ultrasound EPDs
A second model specification including car-
cass ultrasound EPDs was estimated to
explore the value that buyers place on carcass
quality. Age, actual weights, production
EPDs, marketing factors, and sale dummy
variables were included in the model, while
sire rankings were excluded because of limited
data. The model is specified as
In price ~ b0 z b1age z b2age2 z b3birthwt
(3)
z b4adjweanwt z b5adjyearwt
z b6birthepd z b7 weanepd
z b8milkepd z b9yearepd
z b10uimfedp z b11uribepd
z b12ufatepd z b13uprpepd
z b14saleorderz b15picture z b16et
z b17sementhirz b18semenhalf
z b19fullbrotherz b20pathfinder
28
z b21 seasonofsale z cj salej z e:
j~ 1