Dr. John Hough, EPD International

Accurate pedigree and performance information going into the Senepol Cattle Breeders Association’s performance program is essential in calculating accurate EPDs. Accurate weights,
correct pedigrees, whole herd reporting and correct management identification are just a few of the factors essential in calculating accurate EPDs. Correct identification of contemporary groups
could be the most important key in calculating accurate EPDs. With calves grouped incorrectly,
the accuracy of EPDs is less than possible.

Each Senepol breeder provides SCBA with the pertinent information. The EPD International
computer systems actually assign contemporary groups. Calves are ratioed within a single contemporary group and the University of Georgia calculates EPDs based on comparisons within a
single contemporary group. The SCBA computers assign contemporary groups according to a
specific set of guidelines based on information provided by each Senepol breeder. Breeders
provide the general information and the computers designate the actual contemporary groups based on this information.

Contemporary group definitions

A contemporary
group is defined as a
group of calves that
have had the same
opportunity to
perform. This means
they are from the
same herd, sex, born
in the same season
and raised under
similar management
and environmental
conditions.
Specifically, SCBA
defines
contemporary groups
in the following
manners.
Birth Contemporary
Group — A group of
calves from the same
herd (although not
necessarily in the
same ownership), the
processing group
(batch of work sent to
SCBA), the same sex
(male or female), the
same percentage
Senepol (3/8, 1/2 ,
3/4 and 7/8 and
above) the same
management
(management of the
dam during
gestation) and born
within 90 days of one
another.

Weaning
Contemporary
Group — A group of
calves from the same
herd and processing
group, the same
weaning sex (bull,
steer or heifer), the
same percentage
Senepol, the same
feed code (creep fed,
non-creep fed, etc.),
the same
management
(different pastures or
other management
differences) and
weighed within 7
days of one another.
All calves should be
weighed between
160 and 280 days of
age.
Yearling
Contemporary
Group — A group of
calves from the same
weaning
contemporary group,
the same yearling
sex (for example, bull
at weaning and a
steer at yearling), the
same feed code
(high grain,
roughage, etc.), the
same management
(different lots or other
management
differences) and
weighted within 7
days of one another.
All cattle should be
weighed between
310 and 430 days of
age.
Many
Performance
Records are
Removed
Unfortunately, many
records are edited
out of the database
prior to calculating
EPDs. There are
several reasons
some performance
records are thrown
away. Calves from
single-calf
contemporary groups
can not be used in
the EPD analysis.
Calves weighed
outside of the
acceptable age
ranges are not
utilized. Embryo
transfer calves and
twins are not used.
Calves with unknown
sires or dams are not
used in the EPD
analysis. All
precautions should
be taken to insure
that a minimum
number of records
are deleted prior to
the EPD analysis.
Consequences
of Incorrect
Contemporary
Grouping
When calves are
grouped together
incorrectly, ratios and
EPDs calculated will
not be as accurate as
they should be. For
example, let’s say
you have a group of
calves that are
running on two
different pastures.
Pasture “A” has 20
pairs on a high
quality improved
pasture and calves
wean at an average
of 600 lb. Pasture “B”
has 20 pairs on a low
quality unimproved
pasture and calves
wean at an average
of 500 lb. If you
group all 40 calves
together, the average
weight is 550 lb. A
calf from pasture “A”
weighing from 550 lb.
has a ratio of 100
(550 / 550 X 100 =
100). A different calf
from pasture “B”
weighing from 550 lb.
also has the same
ratio of 100. The
EPD analysis treats
these calves exactly
the same because of
your directions.
In reality, the calves
should have been
grouped separately
because of the vastly
different pasture
conditions. If pasture
“A” calves would
have been grouped
separately with an
average weight of
600 lb., the 550 lb.
calf would have had
a ratio of 92 (550 /
600 X 100). If
pasture “B” calves
would have been
grouped separately
with an average
weight of 500 lb., the
550 lb. calf would
have had a ratio of
110 (550 / 500 X
100). Both calves
when pastures where
combined ratioed
100, but really should
have ratioed either
92 or 100 when
pastures were
grouped separately.
The EPDs calculated
from a calf with a
ratio of 92 would be
considerately
different from one
with a ratio of 100
and certainly different
from one with a ratio
of 110.
When calves are
grouped incorrectly
ratios are calculated
incorrectly. When
ratios are calculated
incorrectly, EPDs are
calculated
incorrectly. Calves
raised in different
pastures do not
necessarily belong in
different
contemporary
groups. If two
pastures cause the
calves to perform
differently, the calves
should be grouped
separately. If two
pastures are identical
and calves perform
similarly, the calves
can be grouped
together.
First-Calf
Heifers
One question that
always arises is how
to group first-calf
heifers. Are calves
out of first-calf heifers
automatically
separated into
different groups from
calves out of mature
cows. The answer is
no. Unless a breeder
indicates the first-calf
heifers’ calves are
managed differently,
they will be grouped
with the mature
cows’ calves. Many
breeders are not
aware, but do under
normal management
practices separate

the first-calf heifers
and give them extra
feed to allow them to
continue to grow and
re-breed. Under this
scenario, the calves
should definitely be
grouped separately
with different
management codes.
When first-calf
heifers are allowed
better feed and still
grouped with mature
cows, their calves get
a double advantage.
The calves get the
advantage of their
mothers being fed
and they receive a
substantial age of
dam adjustment in
their adjusted
weaning weight
calculations. Either
feeding the dam or
receiving the age of
dam adjustment is
perfectly fine, but not
both. When first-calf
heifers are given
superior treatment
and grouped with the
mature dams, the
EPDs calculated
from these weights
are biased upward.
The EPDs are really
better than the dam’s
production because
of the double
advantage given
them. When their
heifers get older with
additional progeny,
their EPDs will drop
because they no
longer receive the
added feed and
added age of dam
adjustment.
When grouping firstcalf
heifers
incorrectly, the dams
and their calves are
given unfair
advantage. With any
genetic analysis
system, when some
animals are given
unfair advantage,
others are given
unfair disadvantage.
The mature cows’
calves are given a
disadvantage under
this example.
Therefore their EPDs
are lower than their
true performance
indicates.
In many cases,
certain bulls are used
for calving ease and
are only bred to firstcalf
heifers. If these
heifers are treated
better and grouping
together with mature
cows, EPDs
calculated for the sire
are also biased
upward to a large
degree.
Managing first-calf
heifers differently
than mature cows,
many times makes
good management
sense. Breeders
must realize under
this type of
management, the
progeny of these firstcalf
heifers must be
grouped separately
from the mature
cows’ calves.
Large Groups
versus Small
Groups
There are two ways
to group calves
incorrectly. One is
grouping calves that
should not be
together. The other is
separating calves
that should be
together. The first is
a much more serious
problem that the
second. For overall
accuracy,
contemporary groups
should be as large as
possible and still
meet the correct
contemporary
grouping
requirements. A
larger group means
can be directly
compared to one
another. Calves
should never be split
simply to have more
groups or because
you do not want one
calf to be ratioed
against another.
Identifying
Contemporary
Groups
Correctly
Incorrectly grouping
calves in
contemporary groups
is probably the single
most important factor
contributing to
inaccuracy in EPDs.
It is absolutely
imperative that all
Senepol breeders
know how calves
should be correctly
grouped. A
contemporary group
is a group of calves
that have had the
same opportunity to
perform. Grouping
calves together that
have had different
management or
environmental factors
causes serious
problems in the
calculation of EPDs.
If you are at all
unsure how to assign
calves within
contemporary
groups, please call
the SCBA office for
clarification or more
information.