Practical
pointers from Signet when full recording
Gimmer weights (Mature Size)
electing for growth rate without measuring the mature size of the
ewe can increase the size of the breeding female over time. Where
the aim is not to change the mature size, most breeders are interested
in identifying “curve benders”, those animals that have high growth
potential but do not increase the mature size of the breed. Where
a breed, or flock’s, objective is to change the mature size then
this can only be achieved by taking this weight and selecting animals
using the Mature Size EBV.
Weighing gimmers before putting to the tup for the first time
can monitor and identify genetic potential for Mature Size. Submit
the weights to Signet on the Gimmer weigh sheets sent to you.
Accuracy
To ensure that the ranking of your animals is the best prediction
we can provide, it is important that the data on which the EBVs
are based is as accurate as possible. There are a number of opportunities
for inaccuracy due to faulty equipment or human error, but we can
all be a part of keeping the error rate as low as possible.
Signet ensures that there are validation checks at each stage
of our data processing and Egenes also identify any extreme data
and will exclude it from the analysis and issue error reports for
Signet to act upon. All scanning technicians have to successfully
complete accuracy and repeatability tests.
Not surprisingly, an incorrect animal’s weight within a “breed”
analysis will have an insignificant impact on the analysis as a
whole. At a flock level, particularly in small flocks, it can have
a greater effect on the flock rankings and the individual’s EBV
predictions.
Please play your part in helping
to ensure accurate recording:
Record all lambs – ensure that you record the
details of the entire litter for any ewe’s lambing, not just the
lambs you think are good or that you want to retain. Include all
fostering and embryo transfer details.
Weigh crates – keep these in good condition and
oil them before use. Check that they are weighing accurately by
using a couple of 20kg bags of feed. It is important that the weights
are accurate between 15 and 45 kgs at 8 weeks of age rather than
worrying that the indicator needle always returns to zero.
Weigh sheets – weigh lambs between the ages of
42 and 84 days of age to ensure that an adjusted 8 week weight
is calculated. A weight at 8 weeks indicates that the ewe has reared
a lamb and is used for the calculation of both 8 week and Maternal
Ability EBVs. Usually a flock can find one day to weigh all lambs.
If your lambing is protracted, or you lamb in two distinct periods,
you may have to weigh later lambs on a later weigh day. Always
work out the latest day to weigh by adding 84 days to the date
the first lamb was born.
Weights – whether you submit on a paper-based
weigh sheet or send Signet the weights via email in a spreadsheet,
please remember to indicate the weigh date/s and whether the weights
are in lbs or kgs. It may seem obvious to you but a series of weights
around 35-45 could be either lbs or kgs depending on breeding,
feeding and management.
8 week results– this is an important printout
whether you use it for selection and culling purposes, or just
for checking the data we hold on the database is accurate:
-
Check all lambs alive in your flock are listed on the printout
and are the correct sex
-
Check that lamb dates of birth are correct
-
Check that each lamb has a sire and dam and they are correct
-
Where any lamb does not have a sire or dam, inform Signet
of any missing information
-
Check
all lambs have an adjusted 8 week weight, if not, check your
own records to ensure that they were weighed and within the correct
age range
-
Check all lambs have an adjusted 8 week weight, if not, check
your own records to ensure that they were weighed and within
the correct age range
-
All adjusted 8 week weights will be expressed in kgs, irrespective
of whether they were submitted in lbs or kgs. Check that the
weights look correct
-
Check that the stock sire identities are accurate
-
Use the ram progeny list to check that stock rams used in
your flock over time have not been mistakenly recorded under
more than one identity
- If you want the ram name listed, inform the Society of the
missing information
Scanning– if you have submitted your lambing
data in plenty of time, the technician will have received an electronic
file of your flock. As each lamb is scanned the identity and sex
is cross-checked and ensures another point of validation. When
completed, the technician will leave a printout of the raw data
showing all the lambs in your flock, sire and dam of lamb, and
the scanning information including age at scan, weight, muscle
and fat depths.
-
Identify any different management groups accurately. Early
and late lambing groups may need scanning at different dates.
Show teams may have been fed differently, you must inform your
scanner to ensure that lambs have been managed in separate feeding
groups.
-
Rear lambs in as large a contemporary group as possible.
Recording small numbers of lambs, or having them evaluated within
several small groups means elite lambs are less likely to stand
out. If small groups have to be used ensure the scanner is aware
of them.
-
Ensure the lambs are old enough to scan. Scanning data
for any lamb under 84 days of age at scanning will be excluded
from the analysis.
-
Check that the weights look correct (they will
be expressed in kgs)
-
Check that there is a muscle and fat depth
present for all lambs scanned.
-
Check the sire and dam is correct
for each lamb.
Final results– if you have taken steps above
to check your data, the final result printout should not need further
checking for data accuracy and can confidently be used to aid selection
decisions.
If you have not received an earlier printout, please follow the
checklists above.
Using EBVs
to make the best breeding decisions
Breeding evaluations are relatively risk averse, depending on
good quality data to identify animals that are truly genetically
superior. Don’t select sheep on EBVs alone, as this provides no
guide to structural soundness, but equally don’t select them entirely
“by eye”
Set flock breeding objectives
– then identify EBVs of importance
Before making any breeding decisions consider your breeding objectives
and the strengths and weakness within the flock
Select high EBV
ewe lambs
Some flocks draft the ewe lambs they like the look of into a pen
and then deselect those with poor EBVs; others select those with
the highest EBVs and then cull those they don’t like. Both approaches
should achieve the same objective
Cull low EBV stock ewes
In established flocks the regular replacement of older, low EBV
stock ewes with high EBV shearlings will greatly increase rates
of genetic gain. In new flocks the culling of stock ewes on their
EBVs should be carried out with more caution, as less may be
known about their true breeding potential, particularly for maternal
traits
Consider using homebred ram lambs
These may be your best source of genetics. If usually sold as shearlings
they may also provide a cost effective mating solution
Mate the
top stock ewes with care
Only those ewes in the Top 20% of your flock are likely to produce
a future stock ram worthy of use in the home flock. It is vital
you get these ewes mated to the right sire. Occasionally a breeder
puts all of their best ewes to a new unknown sire, this is a massive
risk - which rarely pays off
Using well-known rams
Consider using at least one well-known (from a recording point
of view) sire. The performance of their progeny will enable more
accurate comparisons to be made to other recording flocks. This
might involve exchanging or sharing recorded rams with other
flocks
Testing
rams
Test "unknown" rams as fairly as possible; ensure their
progeny are born at the same time as those by other well recorded
sires. Ensure they produce at least 10-15 fully weight recorded
progeny in any year, more in large flocks
Use Accuracy Values
Accuracy Values indicate the likelihood that an EBV will change
over time. They are useful when assessing the breeding potential
of sheep from less well recorded flocks
All of these decisions should form part of an integrated breeding
plan that also needs to minimise increases in rates of inbreeding
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