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At weaning, draft ewes into condition score groups and allocate the best available pasture to those ewes below score 3.
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Immediately after weaning, plan the grazing management up to next joining.
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Select ewes on rearing ability to make gains towards weaning more lambs. |
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Key decisions, critical actions and benchmarks
Maximise ewe condition
score at the next joining
Wean lambs based on seasonal
conditions or rule of thumb:
Weaning lambs 14 weeks after the
start of lambing is a fairly good rule of
thumb if the joining period was around
six weeks and you are experiencing an
average season with available green feed.
In most situations this will ensure that
ewes are able to regain liveweight and
body condition after weaning while
pasture quality is at a satisfactory level.
If the season is exceptionally good,
ewes are in more than condition score
3 and lambs are growing well, it may be
beneficial to extend the weaning date up
to 18 weeks, provided worm burdens are
carefully monitored.
However, in a very poor (drought) season
there can be a significant benefit to both
lambs and ewes by weaning as soon as
10 weeks after the start of lambing (for
a 5 week joining period) and providing
intensive management to both ewes and
lambs. This may mean drafting ewes
according to body condition, doing a
feed budget on available pasture and
providing supplements as needed to
achieve target body condition for next
joining. Weaning this early is likely
to result in many lambs less than 24
kg at weaning. These weaners will
require sufficient high quality feed or
supplements to grow at more than 1 kg
per month to avoid significant losses.
Worm burdens will need to be carefully
monitored and producers should be alert
to potential trace element deficiencies.
Condition score ewes and draft into groups at weaning
At weaning use tool 10.1 to separate ewes into management groups with the lower condition score groups being allocated the best available pasture. This is a relatively simple, low cost/high benefit management strategy that is worth the investment of your time.
Ewes in low condition score will rapidly gain weight when grazing green feed. But ewes in low condition cost more to supplementary feed once pasture quality deteriorates. They will also have poorer reproductive performance and are at higher risk of losing their lambs at birth.
Selecting replacement adult ewes
Refer to procedure 9.3 in Gain from Genetics for recommended approaches to selection and breeding.
Selection for age
While reproductive performance can
still be good in older ewes, death rates
may be higher and fleece values lower.
The optimum sale age for older ewes
is between 4 and 6 years depending on
flock structure, management plans and
relative livestock values.
In non self-replacing breeding flocks
the cost of replacement ewes influences
the ideal sale age. Meat breed ewes are
normally kept for 1-2 years longer than
Merinos.
Dry Ewes
Ewes that fail to get in lamb in any one
year have a low repeatability of failing to
get in lamb the following year. However,
ewes that fail to get in lamb 2 years in a
row should be culled.
Select for rearing ability
Small, but consistent, gains can be made towards weaning more lambs by culling those ewes which lamb, but fail to rear their young. The ‘wet and dry’ technique (stripping fluid from the udder at lamb marking) is used to identify ewes that are either rearing a lamb or have lambed and lost. Ewes not rearing a lamb have some udder development but tend to have clear fluid and teats that are dirty. Dry ewes have no birth stain on the breech and little udder development.
The progressive gains from culling maidens that fail to rear a lamb include:
- Ewes that reared as maidens rear 10% more lambs at subsequent lambing.
- The ability to rear a lamb is passed on to subsequent generations, especially if ram selection includes maternal rearing ability.
Genetic selection for reproductive performance
Reproductive traits have low heritability so genetic gains are slow. Ewe liveweight is correlated with reproductive performance. Scrotal circumference in rams is correlated with ovulation rate in ewes. Setting breeding objectives in a commercial flock is discussed in procedure 9.2 in Gain from Genetics.
In terminal sire breeding flocks where ewe replacements are purchased, consider freedom from disease and genetic merit when determining the purchase price. Use all the genetic information available from ewe and ram databases (from LAMBPLAN ASBVs) to make decisions when purchasing replacement ewes (see tools 9.3 and 9.6 in Gain from Genetics).
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Careful management of ewe nutrition after weaning to maximise condition score at joining.
