In the case of this event, National Western Stock Show, field level is only for staff photographers. I was in that group 2 years ago and it was not a pleasant experience. Lower rows, starting at about 15 feet are possible but at a cost and you need to get them months in advance.
A99| A77| A700 | QX10
Bower 8mm & 14mm
Sony 28-75|70-300G|70-400 G
Minolta 35-70|50mm|200 G|1.4 & 2X TC
Sigma 18-250|70-200|50-500|2X TC
Tamron 90|1.4 TC
Albums at www.sony-snapper.com