The anthrax outbreak in the New South Wales Upper Hunter region has spread to another farm, meaning five properties have now been quarantined since Christmas Eve.
The Department of Primary Industries said the latest property is nearby four other affected farms at Rouchel near Scone.
But it says despite the spread, the outbreak's still considered to be contained.
DPI spokesman Brett Fifield says three thousand vaccinations are up in Scone, and will be distributed to livestock owners.
Mr Fifield says about 20 beef cattle have now died as a result of the outbreak.
He says all the carcasses have been cleared and the properties will be quarantined for a minimum of 41 days.
The quarantine bans the movement of all farm animals onto or off the properties.
Spores of the naturally occurring anthrax bacteria can remain inert in the soil for decades, and they're known to become active after a period of heavy rain.