That is not what we are hearing out here in Arizona.  In AZ and other arid western states, cattle tend to congregate in riparian areas with the result being a break down of the banks of streams and fouling the water.  As to the feed grown for cattle, in 1985 80% of the water was used by agriculture, much of it being for alfalfa.  That figure is down to around 70% in 2000, but still substantial.
  Bob Eidsmoe    now of Rio Verde, AZ