|
| This zone is
characterised by
winter rainfall
and a mix of
annual and
perennial
grasses together
with
combinations of
variuous
clovers. The
limited growing
season through
cooler soil
temperatures,
shortening day
length and cold
winters limit
pasture growth
in the middle of
winter. This
seriously
affects the
potential
stocking rate
and pasture
utilisation and
therefore
affects the
recommendations
for ewe
management. |
|
The economic analysis that
supports these
recommendations is generated
using the Western Victoria
MIDAS model. Download
the full report of
the modelling for this
region (250kB
PDF)
Ewe Condition Score Targets
Ewe Condition Score at
joining and at lambing set
the framework of the profile
and the environmental
conditions, including
expected level of pasture
available in late-pregnancy,
dictate the shape of the
profile for a particular
region.
Print out and plot the CS of
your mob against the
targeted CS profile, so that
by the end of the year you
have a CS profile for your
own ewes.
Remember - ewe CS
for joining can be
influenced from weaning
and therefore it is
important to monitor
changes in ewe condition
between weaning and
joining.
Spring
lambing
provides
the best
match of
pasture
availability
to the
energy
needs of
the ewe
and
lamb.
This
match
can
allow
more
sheep to
be run
relative
to
lambing
at other
times of
the
year.
The optimum profile for spring lambing flocks in the High Rainfall Zone (HRZ)
as seen in Figure 1 is:
- to allow moderate loss of condition from joining to 'break of season', provided the condition can be regained prior to lambing on green feed
- aim for Condition Score 3 at joining
The most important target for ewe flocks is to regain condition lost in early pregnancy before lambing commences.
Meeting this target gives the optimum profitability.
Figure 1.
.jpg)
Ewes can lose some condition (0.3 of a condition score) over early pregnancy, however, they must regain all condition lost in early pregnancy by lambing.
Failing to meet the lambing target will decrease the value of the ewe's production by $16 per condition score. It costs at least $12/ewe to gain a condition score with grain feeding. Therefore gaining condition must be done with green feed.
Ewes require 800kg/ha FOO by day 90 and 1200 FOO by lambing for single ewes and 1800 FOO for twinning ewes to regain lost condition. If this amount of green feed isn't likely to be available then the next best approach is to maintain ewe condition throughout pregnancy. Establishing pastures should be deferred so that FOO targets can be reached.
Cost of not following the profile
If the regain in condition by lambing isn't made and the ewes continue to lose condition in late pregnancy to CS 2,
large penalties from ewe and lamb mortality will be incurred.
Maintaining ewes at their joining condition throughout pregnancy is expensive (approximately $2.65/ewe compared to losing and regaining) due to the extra hand feed over autumn.
However, this option is still more profitable than allowed to lose condition and fail to regain it in the last third of pregnancy.
If ewes are allowed to lose over autumn but only maintained in condition after day 90 (rather than re-gaining condition), $3.65/ewe lower profit will be achieved following this profile compared to the optimum (figure 1). This could be as much as $30,000 on a 1000ha enterprise!
Figure 2.
Profile 1. Profit is lower due to higher supplementary feeding costs in autumn
Profile 2. Optimum due to lower feeding in early pregnancy and regaining condition on green feed
Profile 3. Profit is lower due to impacts from lower condition at lambing
Profile 4. Ewe and lamb mortality severely limits profitability
Running lower Stocking Rates
These profiles are suitable for flocks run at stocking rates lower than the optimum and at lower stocking rates will return a higher profit than those run at a lower condition for lambing.
However, following the lifetimewool ewe profile can allow you to increase stocking rates safely and thereby further
increase profitabilty.
In years that ewes' peak condition prior to joining is above 3, it is worthwhile following the general trend of losing 0.3 of a condition score from end of joining to the break of season and regaining it all by lambing for that season rather than trying to drop further (0.6 CS) and regain only some of the lost condition at lambing. There is a difference of $376/ha profit (CS 3.3 at joining, 3.0 at day 90, 3.3 at lambing) compared to $351/ha profit (CS 3.3 at joining, 2.7 at day 90, 3.0 at lambing).
Continuing to run ewes at this higher flock condition score will give a similar profitability to runninng ewes at the optimum profile, as the higher production gains are offset by the higher cost of supplementation.
Aiming to be on this profile every year or in an average year will be slightly more expensive as it takes more supplement to grow maiden ewes to the higher starting condition score.
Trade-offs of risk for profit
The optimum profile shown in Figure 1. takes into account both profitability and the health of the breeding flock. The
alternative profile shown offers similar levels of profitability, but there are some important trade-offs to consider.
Ewe mortality generally increases with lower ewe condition by lambing (there are other factors such as weather, age and available feed). Ewe condition in late pregnancy has a large impact on lamb birth weight and therefore lamb survival.
There is a compensatory gain effect on lamb birthweight when ewes that have lost condition regain it in late pregnancy.
Twin lambs are more sensitive to this change in birth weight (& survival) as their birthweight is usually further from the optimum.
Table 1 shows the effect of several profiles on both lamb and ewe survival.
Table 1. Difference in survival of ewes and lambs for late lambing flocks compared to maintaining condition throughout pregnancy in the Western Districts of
st1:state>Victoria
.
Profile
|
Lamb survival % difference
|
Ewe survival % difference.
|
|
Joining CS
|
Day 90 CS
|
Lambing CS
|
Single lambs
|
Twin lambs
|
1
|
3
|
3
|
3
|
0.0
|
0.0
|
0.0
|
2
|
3
|
2.7
|
3
|
+0.8%
|
+4.5%
|
+0.1%
|
3
|
2.7
|
2.5
|
2.7
|
-3.9%
|
-2.7%
|
-1.7%
|
a
|
2.7
|
2.2
|
2.2
|
-17.8%
|
-22.6%
|
-6.1%
|
Following a lower, but similar shaped profile (profile a) to the optimum (profile 2) means that at 'break of season', the flock average will be CS 2.2. The mob will require careful monitoring and if the mob fails to regain condition to 2.7 by lambing severe penalties in ewe and lamb mortality will result.
Profile a in Table 1 shows that twin lambs have a predicted decrease in survival of 23%!
This can be compared to the optimum profile which can increase twin lamb survival by 4.5%.
As well as this, individuals in the mob will be below the recommended CS 2 for pregnancy and at risk of mortality.
Getting it wrong when following the lower profile will impact on acceptable stock husbandry as well as profitability.
The Condition Score profile is for the average of the flock. Usually in each flock there will be some individuals at least 0.5 of a condition score lower (and an equal proportion that are 0.5 of a condition score higher).
Individual ewes should not be below CS 2. Ewes at or below CS 2 during pregnancy should have preferential treatment to regain condition prior to lambing as ewe (as well as lamb) mortality increases dramatically when ewes are below CS 2.
Download the full MIDAS economic analysis report (250kBs pdf)
Or choose the general topic required :
How whole farm profit is affected by the condition of ewes
Improving ewe fleece weight and wool quality
Ewes in better condition at joining conceive more lambs
Improving lamb survival
More productive lambs through better ewe management
Managing twinning ewes for higher production
Managing ewe mortality
or download/ request a hard copyof the Ewe Management Handbook for the High Rainfall Zone
Tools including Pasture photos, condition scoring and feed budgeting
For more information on lifetimewool please contact
Tasmania: Andrew Bailey (email)
Dept. Primary Industries & Water
PROSPECT Tel: 03-6336 5381
For further information on lifetimewool activities and results please visit the 8x5 Wool Profit Program website;
www.8x5.com.au
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