Shelter options for increased lamb survival
| Project start date: | 01 May 2018 |
| Project end date: | 01 May 2022 |
| Project status: | Completed |
| Livestock species: | Lamb |
| Relevant regions: | Southern Australia |
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Summary
Climate in southwest Victoria dictates that the main lambing season extends from June to September. Optimum lambing time is largely driven by the need to match peak energy demand with a consistent supply of quality pasture. However, this period corresponds with the highest frequency of ‘chill’ days and therefore the most risk to young lambs.
The aim of this Producer Demonstration Site (PDS) was to show the potential economic, social and environmental benefits of increased shelter for lamb survival through the establishment of a variety of shelter options.
All shelter options were effective at reducing the percentage of time when the chill index was considered high (that is, greater than 1000kJ/m2/h). The plantation provided the greatest reduction of high wind chill with a decrease of 18%, followed by TWG (15.4%), hay bales (14.7%), and corrugated iron shelters (11.5%). D. hirstum provided the smallest reduction in time at high wind chill with a decrease of 7.3%, however, this was influenced by poor establishment and small, slow growing plants.
Objectives
The project aimed to demonstrate the economic, social and environmental benefits of increased shelter for lamb survival through the establishment of hedgerows of tall wheat grass and leguminous shrubs, as well as constructed shelters using hay bales and corrugated iron. Opportunistically, the third and fourth years of the project also demonstrated using eucalypt plantations. In addition to the benefits of increased shelter, the project set out to demonstrate how to establish and maintain the shelters.
Progress
Improvements in lamb survival did not occur across all shelter types. Plantations delivered the biggest improvement, increasing survival by 15.7%, followed by hay bales (5.3%) and TWG (1.8%). The presence of corrugated iron shelters correlated with an overall reduction in lamb survival, of 2.7%. These results were also influenced by the amount of shelter coverage across the paddock as well as sheep breed, feed on offer and lamb birthweight.
Economic analysis of the tall wheat grass shelter in this demonstration found it to be a profitable investment. A breakeven analysis found that an extra 2.9 lambs on the 37-ha tall wheat grass shelter paddock compared to the control paddock is required to justify the tall wheat grass shelter establishment (at a lamb price of $127/hd).
Utilising already-existing forms of shelter on farm, such as eucalypt plantations with good understorey, presented a good opportunity to improve lamb survival.
