Should Pima County be in the cattle business?...by Tim Vanderpool...There was a time when cow-punching defined Southern Arizona. Acre after acre of cattle country spilled across the range, some of it beautiful, some of it grazed to the nubs. Today, the cattle ranching industry is largely in decline, a victim of shifting markets and ongoing drought. But there's one rancher who seems set for the long haul, and its name is Pima County. Under the dictates of the Sonoran Desert Conservation Plan, county officials have bought up a slew…