Something else you could try Bob, put a good sized piece of a brightly colored fabric, yellow or red, on the other side of the field away from your freshly invaded stand area, it seems that cattle are attrected to brightly colored objects in their pasture. I found this out when as a youth I set up a Yellow two man tent in a remote corner of a cow pasture, came back a hour latter and it was surounded by cattle. It might work, and certainaly worth the try.