Management
plant as a production metric,
why should pounds per cow
be used in the beef industry?
The objective of this decision
aid is to provide producers an
additional metric to determine
if raising replacement heifers
is the most efficient use
of ranch resources. Input
variables include: number
of cows, replacement rate,
weights of cattle marketed,
expected prices received/paid
for: calves, cull cows, and bred
heifers. According to input
variables, net energy devoted to
producing cows and developing
heifers is quantified. Total
net energy is the sum of that
devoted to cows and heifers,
respectively. The decision aid
then calculates how many
cows are currently displaced
by developing heifers. Lastly,
the decision aid is also unique
in that additional performance
attributable to heterosis in
the purchased replacement
heifer system is accounted for.
Heterosis is the key to
maximizing production
efficiency through a
combination of individual and
maternal heterosis advantages.
The combined effects of
maternal and individual
heterosis yields a 20-28%
increase in pounds weaned /
cow exposed /year (Spangler,
2007; Weaber, 2015). In a
crossbreeding system where
F1 females were mated to a
terminal sire of a different breed,
the observed advantage was
23.3% (Gregory et al., 1965;
Cundiff et al., 1974). In this
system 8.5% of the heterosis
advantage was attributed to
individual traits (Gregory et al.,
1965) and 14.8% was attributed
to maternal heterosis from the
crossbred cow (Cundiff et al.,
1974). This demonstrates the
importance of both maternal
and individual heterosis, namely
the benefit of the crossbred cow.
Purchasing bred crossbred
females for use in a terminal sire
system is an attractive solution
as it offers the simplicity of
managing a straight-bred
herd, while simultaneously
maximizing herd heterosis.
The upfront cost of purchasing
bred crossbred heifers can
sometimes be a deterrent
but failing to maximize ranch
productivity could be much
more expensive. This decision
aid will assist producers to
visualize the costs associated
with raising heifers and if those
resources were reallocated
to the mature cow herd how
much they could afford to
spend when purchasing
replacement bred females.
In summary, the decision aid
used to compare the two
systems is rooted in biology.
According to user input, the
production potential of the
operation is estimated and
carrying capacity is calculated.
Paired with economic conditions
unique to each individual
operation, the decision aid
will hopefully simplify the
replacement heifer dilemma. I
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