There are hopes that virtual fencing technology, which is increasingly being adopted on Tasmanian dairy farms, could be used to optimise pasture consumption and boost milk production by developing novel grazing regimes that support the natural behaviours of livestock.
Dr Megan Verdon, Senior Research Fellow at the Tasmanian Institute of Agriculture (TIA), received funding from the Tasmania Government through the Agricultural Development Fund to work with the dairy industry to explore the productive benefits of Halter virtual fencing technology. The project is called Virtual fencing: A game changer for pasture-based livestock systems.
Dr Verdon is an animal welfare scientist and has been leading research on virtual fencing technology for several years, including publishing the world’s first evaluation of virtual fencing technology in the dairy industry in 2021.
In this latest project, Dr Verdon is collaborating with Tasmanian dairy farmers that are early adopters of virtual fencing technology to learn from their experience and share insights with others that are interested in using the technology in the future.
“The research is guided by dairy farmers who are sharing their on-the-ground experience using the technology and what they see as possible future uses,” Dr Verdon said.
“A top priority that farmers identified as a future use for virtual fencing technology is around new and novel ways to optimise grazing. Farmers are interested in opportunities to increase the amount of pasture that cows are consuming to support increased milk production – and doing this in a way that maintains or improves animal welfare.”
Dr Verdon said previous research conducted by TIA has looked at encouraging cows to feed more frequently to increase pasture intake, but this resulted in animals feeding at the expense of rumination which upset the normal balance and reduced milk production.
This trial takes a different approach by focussing on aligning pasture availability to the natural grazing behaviours of cattle. The complex grazing regime would be labour intensive using conventional electric fencing but is facilitated by virtual fencing technology.
“Dairy cows have natural behavioural fluctuations and like to have their main feed in the evening, a little top-up at night, a small meal at dawn, and then snack during the day,” Dr Verdon said.
“We designed a grazing trial to work with the natural behaviour of dairy cows by aligning the availability of food to when cows want to eat.”
A five-week trial involving 160 cows was conducted at the TIA Dairy Research Facility at Elliott in North-West Tasmania during spring 2024.
The treatment groups were provided with the bulk of their pasture allocation (65 per cent) in the evening, a small allocation before the morning milking (15 per cent) and a top-up after the morning milking (20 per cent).
The research team studied the effect of this optimised grazing regime on pasture utilisation, cow health, cow behaviour, and milk production.
The treatment groups were compared to control groups involving a typical grazing regime with 50 per cent of the daily pasture allocation provided after the morning milking and the other 50 per cent after the afternoon milking.
Data was collected to monitor the effectiveness of the novel grazing regime, including monitoring pH levels as an indication of cow digestive health. A proportion of cows were given a smaXtec bolus as a non-invasive way to continuously monitor pH levels for subacute ruminal acidosis (SARA) and acidosis.
Preliminary data indicates that the optimised grazing regime significantly reduced the time that cows spent in SARA and acidosis.
“Acidosis, including subclinical acidosis, is a metabolic disorder that occurs when the rumen pH drops below the normal range. Our experiment showed that cows in the treatment herds spent 60 per cent less time in subclinical acidosis and 86 per cent less time in clinical acidosis compared to the control cows,” Dr Verdon said.
“These results are promising. Acidosis and subclinical acidosis lead to reduced feed intake and nutrient absorption, resulting in lower milk production and impact cow health.”
The research team is continuing to analyse data in 2025 around milk production, pasture utilisation and animal behaviour. This will provide more information around the potential benefit of this optimised grazing regime.
Watch Dr Megan Verdon speak about the virtual fencing research at the 2025 TIA Dairy Research Facility Field Day.
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