Take home messages

• Spatial grazing technology could help to overcome the poor grazing efficiency and uneven distribution of grazing pressure when grazing large paddocks.
• Many grain growers (mixed farmers) expect that spatial grazing using virtual fencing, if available, would be very beneficial to their farming system.
• Whole-farm economic analysis of soil-specific pasture grazing shows that this practice has the potential to increase farm profit and substantially increase the role of livestock on mixed farms.
• The results offer encouragement for the ongoing pursuit of cost-effective virtual fencing technology for sheep.
• Virtual fencing technology for cattle is in the later stages of development.

Background

Achieving optimal integration of cropping and grazing remains a major management challenge. As an example, increasing paddock sizes (or in some cases removing fences) to increase cropping efficiency usually reduces the ability to graze efficiently and manage any areas vulnerable to soil erosion. There is potential for sub-paddock fencing to improve both cropping and livestock productivity by managing grazing pressure of pastures, grazed crops and crop residue within cropping paddocks. Being able to avoid excessive grazing pressure on the most vulnerable parts of the paddock could also make grazing more profitable and less risky when meeting the increasing demand for early-season crop grazing to provide winter feed for livestock.

Electric fencing for sub-paddock grazing is rarely used because of the labour, costs and other difficulties associated with managing temporary fences on large mixed farms. The potential for virtual fencing using GPS-enabled devices which are attached to animals and provide a signal to animals to deter them from grazing in particular areas of a paddock is an attractive option to many farmers. Other potential benefits of spatial grazing include the ability to target grazing on areas of paddocks with high weed levels, reduce grazing pressure on vulnerable areas of establishing pastures, reduce risk of crop yield loss caused by overgrazing vulnerable areas of grazed grain crop, and protect areas for revegetation. The commercial release of such a device designed for cattle is proposed in the near future (Agersens website). However, only relatively recently has attention been given to the potential for virtual fencing for spatial grazing of sheep.

Potential demand for virtual fencing by grain growers

In a study of the grain grower’s use of precision agriculture technology across 12 southern and western grain growing regions, 48% of grain growers with livestock expected that they would get substantial benefit on their farm from a technology that could control where livestock grazed using electronic collars or ear tags (Llewellyn and Ouzman 2014).

Spatial grazing behaviour of sheep

The spatial grazing behaviour of a flock of 200 two-year-old merino ewes was tracked while grazing in a 107ha paddock near Nandaly, Victoria, with a range of soils commonly associated with Mallee paddocks (deep sands to clay loams) (Moodie et al. 2016). Twenty five of the animals were fitted with UNE Tracker II GPS collars. The sheep grazed a vetch paddock from 28 July to 17 September 2015 and vetch biomass was monitored at 25 locations. Sheep were found to concentrate 50% of their time on 25% of the paddock (Figure 1). A further 25% of the paddock was left unutilised despite the high availability of quality feed on this area. It was estimated that an additional 65 ewes with lambs could have been fed if the paddock was evenly utilised.

Figure 1. Livestock residency index (hours spent grazing) in 30m x 30m cells for 10 day periods in a Nandaly vetch paddock (Source: Moodie et al. 2016).

Whole-farm economics of spatial grazing

Whole-farm economic analysis was used to evaluate the potential profitability of sub-paddock grazing technology in a low-rainfall Mallee region with typically high levels of soil variability and the potential for soil-specific management (Llewellyn et al. 2017). The analysis only considered the livestock production benefits of spatial grazing of pastures. It assumed that spatial grazing would allow sheep to graze according to the minimum groundcover threshold (residual pasture biomass) for different soils within a paddock, instead of having to remove sheep from an entire paddock when the groundcover (residual pasture biomass) reached the minimum threshold for the most vulnerable (sandy) soil type. Using spatial grazing was shown to potentially increase the profitability of livestock in the system and increase whole farm profit by approximately 10-20% (excluding the cost of the technology) depending on the current status of soil-specific cropping management. Importantly, it greatly increased the potential for higher livestock numbers to increase overall whole-farm profit. In the case of a farmer currently managing six different soil types with different crop inputs across their 3000ha farm, introducing spatial grazing could increase potential whole-farm profit by 15% (depending on cost of the technology) and the profit maximising sheep stocking rate would more than double (with 80% cropping).

Current work on virtual fencing

While virtual fencing technology for cattle is approaching commercial release (Agersens website), work has begun investigating the potential for virtual fencing for sheep. Initial CSIRO trials have demonstrated the potential for control of sheep using virtual fencing collars and work is continuing on research stations and on-farm trials, including a recent small-paddock trial in the NSW Mallee. Unlike cattle, the use of collars with sheep is unlikely to be a long-term solution for commercial devices so technical development of other platforms such as eartags is likely to be required.

Conclusion

Increasing paddock sizes has helped to increase cropping efficiency but has made achieving grazing efficiency and livestock management more difficult. Virtual fencing has the potential to benefit grazing management and productivity on mixed farms. Virtual fencing technology for cattle is expected to be released in the near future. The results presented here offer encouragement for the pursuit of cost-effective virtual fencing technology for sheep.

References

Lee C,  Henshall JM, Wark TJ, Crossman CC, Reed MT, Brewer HG, O’Grady J and Fisher AD. 2009. Associative learning by cattle to enable effective and ethical virtual fences. Applied Animal Behaviour Science 119, 15-22.

Llewellyn RS and Ouzman J (2014). Adoption of precision agriculture-related practices: status, opportunities and the role of farm advisers. CSIRO report published by GRDC. 74pp.

Moodie M, Economou Z, Trotter M,  Frischke A, Murray J. 2016. Livestock grazing behaviour in large Mallee paddocks. Mallee Sustainable Farming.

Llewellyn RS, Monjardino M, Moodie M, Trotter M, Economou Z. 2017. Spatial grazing in mixed farming systems: the potential for virtual fencing. Proceedings of the Australian Agronomy Conference, Ballarat, Victoria, September. Website

Acknowledgements

This research is under the banner of various projects with investment from GRDC, Mallee CMA and the Commonwealth Government Department of Agriculture and Water Resources. The whole-farm analysis and farmer interviews were part of the GRDC-funded CRC Future Farm Industries EverCrop project (CSA00044). The field tracking study was conducted by Mallee Sustainable Farming in partnership with University of New England and BCG with National Landcare Program funding through the Mallee CMA. Funding from the Commonwealth Government Department of Agriculture and Water Resources has supported trialling of the potential control of sheep grazing using virtual fencing. The research is made possible the significant contributions of growers through both trial cooperation and the support of the GRDC — the author would like to thank them for their continued support.

Contact details

Rick Llewellyn
CSIRO, Waite Campus, Adelaide
08 8303 8502
rick.llewellyn@csiro.au