The 150th-anniversary edition of the Iowa State Fair’s entering its final weekend. One of yesterday’s attractions was the sheep dog trials. If you saw the movie “Babe” — the one where a pet pig herds sheep — then you have an idea of what this competition was like. With whistles and commands, an owner directs the dog as it herds sheep into pens and around fences. Des Moines native Tracey Miller lives in South Dakota now. She started competing in sheep dog trials 17 years ago.One of her friends had a border collie that herded sheep, and she “got addicted.” Watching a sheep dog trial is sort of like watching a big tennis match or golf tournament, the fans are quiet, and only clap when the dog has completed its task. “And you don’t want a lot of crowd activity because when you’re working with sheep, as I’m sure you can tell, little things set ’em off,” Miller says. And the dogs don’t bark. “They’re not supposed to. That shows weakness in the dog…it kind of says ‘I can’t do this.'” Miller worries about the sport because there are fewer sheep herds in the countryside. “Trialing is a hobby more than a true art anymore,” she says. She says most of the people who compete now do it as a weekend sport, and don’t raise livestock for a living. State Fair spokeswoman Kathie Swift says the sheep dog trials are another example of the variety of competitions on the fairgrounds.