loading ANT propetyfile using JVMarg attribute

I have a property file for ant which consists of all properties related to my build script. I am trying to load the propertyfile using JVMarg attribute. Please suggest me a way to load the propertyfile.
I tried in following in way, it is not working.
Please suggest me a way to load the property file with the ant task.
<schedule interval="30">
 <ant buildfile="c:\build\build.xml" target="build" time="1450">
  <JVMArg arg="-Dpropertyfile=local.properties">
  </JVMArg>
 </ant>
<schedule>

I appreciate your help.
Satyapal

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