The following article has been contributed by Laura Kemmis of Productive Livestock Systems (firstname.lastname@example.org)
Due to the ongoing dry conditions and the resulting lack of pasture growth, early weaning should be considered as a way to reduce overall feed demand. Feeding a dry ewe and a weaned lamb requires approximately 30% less energy than a lactating ewe/lamb unit, as the conversion of pasture (or supplementary feed) into milk is a relatively inefficient process. Early weaning also gives the ewes more time to regain condition in preparation for joining, allowing greater control over the allocation of feed resources.
Key points for a successful early weaning:
- Liveweight at weaning and post-weaning weight gain are the main factors determining weaner survival. For best results, lambs should be weaned when they reach 20 kg.
- Lambs must be at least 8 weeks old. By this age, a lamb is capable of receiving more nutrients from pasture than from milk.
- Lighter lambs can be weaned but the risk of mortality increases considerably for lambs less than 18 kg (Figure 1). Underweight lambs require a high level of care to avoid losses. A livestock advisor can assist in developing an appropriate management plan.
- Weight gain of lambs can be increased by setting up a creep feeder system which provides lambs access to grain whilst excluding ewes.
- Early weaning may not be suitable if lambing is very spread out as some lambs will be too small and/or young. However, if feed availability is a real issue, heavier lambs can be weaned while smaller lambs remain with the ewes for several more weeks.
- Lamb marking wounds should be allowed to heal properly before weaning.
- At weaning, drafting of ewes according to condition allows preferential feeding of the poorer ewes to improve fertility at joining.
The following graph shows the relationship between liveweight at weaning and weaner survival at 12 months of age. Even small increases in weaning weight can considerably improve lamb survival.
Figure 1 Liveweight at weaning and survival of Merino weaners to 12 months (adapted from: Lifetimewool, 2011, More Productive Progeny through Better Ewe Management.) Note: while the graph is based on data from Merinos, the same recommended weaning weights apply to crossbred lambs.
It is critical that early weaned lambs are given high quality nutrition to promote weight gain and maximise survival. A minimum growth rate of 50 g/day should be targeted. Achieving higher growth rates will further reduce mortality.
Ideally, lambs should be weaned onto high quality lucerne or other legume-based pastures, as these will generally provide sufficient protein to optimise growth. Alternatively, a protein supplement can be fed to weaners on lower quality pastures. Confinement feeding is a practical option when nutrition from pasture is inadequate, although it does require careful management to avoid issues such as acidosis and shy feeders.
When supplementary feeding, lambs should be trained prior to weaning so they are accustomed to the feed type and feeding method that will be used.
Managing weaned lambs:
Regardless of whether lambs are weaned onto pasture or into confinement:
- Smaller mobs improve survival rates of lighter lambs.
- Clean, good quality water is essential to maximise growth.
- Vaccinations should be up to date, especially Pulpy Kidney.
- Worms require management. Worm tests should be used to decide if drenching is warranted.
- Providing roughage reduces the risk of redgut on lush pastures.
- The risk of coccidiosis if trail feeding grain should be considered.
- Weaner weight gain should be monitored if possible. This will help identify any nutritional or management issues before deaths occur.