printStock Journal Technical Column - September 2023
Author: Emma Shattock, Elders Livestock Production Advisor
Everyone knows them. That tail end in a drop of weaners that fail to meet sale targets, produce less and lower quality wool or have high mortality rates. This can be a long-term problem too, with higher percentages of ewe lambs culled out or failing to conceive at their first joining. These issues can represent a large cost to both an individual business and the industry as a whole. The good news is that there are management strategies we can use to minimise this tail to and help ‘at-risk’ lambs remain productive.
The lightest 25% of weaners, often those born as multiples or towards the end of lambing are most at risk. Lighter weaners have fewer body reserves to buffer against short term energy restrictions or appetite loss. They are also the weaners with the highest energy and protein requirements, so drafting these off to manage separately can allow focused management. Other animals at risk include those under higher levels of stress, disease and spring drop lambs which are lighter and younger going into their first summer.
A low post-weaning growth rate can also compromise weaner survival. However, weaning weight and post weaning growth can compensate for each other. High growth rates can lift production in lambs with a low weaning weight. Conversely, poor growth or weight loss after weaning can compromise lambs with a high weaning weight. For this reason, it is critical to minimise time off feed during weaning.
Weaners should grow at a minimum of 50g/head/day but this may need to be higher for lighter weaners. Faster growth allows lambs to accumulate more fat and protein to use as body reserves should feed become limiting. Always check for any underlying causes of poor growth such as worms or shy feeders. Continue to weigh and monitor weaners to ensure they are hitting growth targets through to 18 months of age. Animals falling behind can be separated and managed accordingly.
Weaners have high demands for balanced levels of energy and protein and these demands are even higher for younger, lighter animals or where a high growth rate is required. Additionally, the high nutritional demands relative to size of the rumen means that feed needs to be of good digestibility. High fibre, low digestibility feeds, like straw and hay, cause the lamb to reach ut fill before daily requirements are met. A feed test is important to determine the suitability of a feed.
Imprinting, where the lambs are introduced to a new feed (or other experience) while still with their mother can greatly reduce the time to eat and increase daily feed intake once weaned. This is critical for lambs with low weaning weights. Where imprinting is not possible, trainer animals, such as wethers or non-maternal ewes, can be used to help train the weaners, although this is not as effective as imprinting. Always ensure enough trough space and access to supplementary feed to reduce the number of shy feeders.
Paddock selection is important for tail end weaners. Ideally, paddocks should have around 2000kg DM/ha of green feed with some legume content to meet energy and protein requirements. Spring born lambs will generally be weaned onto dry feed and will require supplementary feeding.
Plan ahead and prepare paddocks with a low worm burden to wean lambs into. Other considerations include managing grass seeds, which can significantly reduce growth rates and shelter if possible.
Ensure water sources are clean, cool, good quality and available in a sufficient quantity. Young stock are also more sensitive to salinity than a dry ewe and this tolerance is reduced further on salty or high protein feed. Insufficient water intake, due to poor quality or lack of access, will reduce feed intake.
Finally, none of these strategies will be effective if disease is holding them back. Weaners have a much more naïve immune system which can be further compromised by stress. A good animal health program can include control for internal and external parasites, clostridial and arthritis vaccinations and supplements for vitamin and mineral deficiencies.
With preparation and good management, it is possible to reduce the number of animals that fall into that tail. By targeting tighter joining, weaning weights, post-weaning growth and disease management, lambs have every opportunity to get ahead.