The first 48 hours of a lamb's life are critical and, according to Lyndon Kubeil, the Victorian co-ordinator for Making More from Sheep (MMfS), selecting the best lambing paddocks is one simple strategy to increase the chances of lamb survival.
"Around 70% of lamb mortality that occurs between birth and weaning occurs within this period. While lamb survival is closely related to lamb birth weight and condition score of the lambing ewes, there are other factors which come into play," Lyndon said.
"There are a number of potential risks with lambing in unsuitable paddocks and these risks can be reduced by planning ahead."
Based on the ‘Wean More Lambs’ module of MMfS, Lyndon recommends the following checklist when choosing the right paddocks for lambing:
The factors contributing to the risk of hypothermia in lambs include combinations of temperature, rainfall and wind speed. Of these, only wind speed can be controlled by using naturally sheltered lambing paddocks.
As a guide, sheltered paddocks can reduce lamb mortality rates by about 10% but shelter will provide less benefit if lambing in location/seasons with mild weather.
Ideally, lambing paddocks that are sheltered from the prevailing winds and provide shelter over the entire paddock are best for lambing. Satisfactory shelter can be provided by trees, shrubs and tussocks.
It is important that shelter belts are designed properly otherwise they may act as wind tunnels when grazing livestock remove the foliage from the lower branches.
The following MLA video outlines the benefits of shelter belts.
Assess pasture targets and available shelter and prioritise lambing mobs accordingly.
As a guide, maiden twin bearing ewes should be placed on the best pasture/best shelter paddocks followed by mature twin bearing ewes of lighter condition, down to single lambing high condition score mature ewes which should be placed on the poorest pasture/most exposed paddocks. If pasture is limited, defer placing ewes into lambing paddocks until as late as possible to help extend feed availability.
When selecting lambing paddocks, consider the sheep grazing behaviour and paddock characteristics and avoid those where ewes are likely to lamb in exposed areas. Preferred paddocks are north and east facing, have good sunlight in the morning, are well drained and provide good access to water.
In high rainfall regions, worms are a major cause of production loss in ewes and poor growth in lambs. Ideally, graze ewes on paddocks with low worm contamination during lambing.
The most important consideration is to match pasture availability with breeding ewe demand. As a general guide, the best results are likely when mob size is as low as practically possible, particularly for twin bearing ewes. Good lamb survival results have been achieved when twin bearing mobs are kept below 200 ewes, most probably due to a lower incidence of mismothering.
Single bearing ewes are less susceptible to mismothering and mob size can be increased to help reduce twin mob sizes if necessary.
It is also preferable to keep stock densities under 18 ewes/ha in twin lambing paddocks.
Best practice is to minimise the disturbance of the lambing flock therefore consider where the paddock is in relation to traffic, noise, sheep dogs etc. If supervision is warranted, the best time to enter the maternity paddock is in the early afternoon.
Develop a routine so ewes will become accustomed to a human presence and will not leave their lambs.
(source MLA Friday Feedback 13/3/15)