Late
winter-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)
(
click on
image for
printable
version
)
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.
