Ewe lambs and maidens
To maximise the productivity and profitability of a breeding flock, ewe lambs require special treatment.
If ewes have had access to appropriate nutrition and been managed well, lamb birth weights should be between 4.5 and 5.5 kg and lambs should have access to a good supply of colostrum.
Good nutrition and ewe management will also minimise the risk of depressed mothering ability and lamb behaviour.
Provided that growth targets for ewe lambs are achieved and good ewe lamb management at joining is practiced, there can be financial benefits associated with joining ewe lambs.
Growth targets for ewe lambs
Ewe lambs can be joined from seven months of age, as long as they are at least 45 kg at joining and are provided with quality feed to continue to grow after joining through pregnancy to lambing. If ewe lambs achieve these targets, acceptable reproductive performance among ewe lambs can be realised.
Ewe hoggets should be managed to reach 75-80% of their mature weight by 15-17 months of age and pasture should be preferentially allocated to ensure this.
Expected lambing percentage from ewe lambs
The lambing percentage of ewe lambs will primarily be influenced by time of joining and ewe live weight. Sheep are seasonal breeders with reproductive activity peaking in autumn, stimulated by shortening day length. Few ewe lambs under 12 months old will cycle naturally before January - a March/April joining will usually be more successful.
The heavier and older the ewe lambs are, the greater the percentage that will successfully cycle, join and lamb.
Selecting the right genetics
By selecting sires with Australian Sheep Breeding Values (ASBVs) that positively influence ewe fertility eg Number of Lambs Weaned (NLW) and Post Weaning Weight (PWT), the reproductive success when joining ewe lambs can be improved - impacting the productivity of the flock.
Nutritional requirements for successful ewe lamb joining
Having managed nutrition so that ewe lambs reach the target weight of 45kg at 7-9 months of age, it is important that good nutrition be maintained to allow the young ewe, plus the unborn lamb, to grow.
If the season deteriorates, supplementary feeding may be required.
Ewe lambs will be in oestrus for a shorter period than older ewes and will not seek out rams to the same extent.
A few management variations can combat this:
- Introducing a higher proportion of rams (minimum 2%) will increase the number of ewe lambs join.
- The use of experienced rams.
- Ensuring that the joining paddock is not too large to enable good contact between rams and ewes.
- Extending the joining time to eight weeks.
- Using the 'ram effect' to initiate puberty and cycling in ewe lambs.
The ram effect
This involves the sudden introduction of rams or teasers (vasectomised rams) in spring to ewes that have been isolated from rams (by at least one kilometre for one month) and will induce cycling in the ewes. For out-of-season joining, teasers can be introduced two weeks prior to rams. This will stimulate ewes to cycle when the rams are introduced and will lead to a more compact lambing period.
Young ewes should be moved into lambing paddocks as soon as the first lamb is born. Ideal mob size for single bearing ewes is less than 300 and for multiple births, no larger than 250. Lambing losses can be minimised through allocation of appropriate lambing paddocks, ideally with a warm, northerly aspect and adequate shelter.
During lactation, maidens should be provided with good-growing improved pasture.
As with ewes, the lambs from maiden ewes can be weaned around 14 weeks after the start of lambing. This will allow maiden ewes time to regain condition lost during lactation to allow successful joining next year.
Financial benefits of joining ewe lambs
Joining ewe lambs rather than joining at 12 or 18 months is estimated to result in a slight increase in returns based on a conservative lambing percentage of 60% lambs weaned/ewes joined.
It is vital to ensure that ewe lambs have reached a target body weight of 45kg and following lambing they are able to regain their body condition before next joining.