ORRRRRRRR... You are actually wrong. Unless of course, you take a random cow farmer and not the average, in which case you may be right. The 2600 gallons is pretty close to be right for grass fed cows in the US.
The
actual source that they quote in your link says 176 gallons for conventional US production of beef. Funny how a site with an agenda can't even quote sources correctly, even when it is in their favor. As a world average, the article quotes 1600 gallons per pound of beef, for conventional production