Except that the bulk of water used by cattle production is that >same< irrigation. I can't find numbers breaking down the irrigation usage, but I would be surprised if it doesn't comprise the bulk of agricultural irrigation.

"By far, the largest component of beef’s water footprint is the huge volume of virtual water consumed by cattle through their feed, in this case both forage and grain."

http://www.news.cornell.edu/stories/1997/08/us-could-feed-80...

Water required to grow the feed for a Holstein Cow: Corn 30,208 L, Alfalfa 201,004 L

http://ianrpubs.unl.edu/live/g2060/build/g2060.pdf