SANTA CLARA — Rather than hold out for a new contract entering the final year of their rookie deals, Colin Kaepernick and Michael Crabtree were on the 49ers' practice field Wednesday looking in sync during organized team activities.

Also practicing was linebacker Aldon Smith, a week after pleading no contest in Santa Clara County Superior Court to felony weapons charges and misdemeanor drunken-driving charges.

Not present for the voluntary program Wednesday were running back Frank Gore, tight end Vernon Davis, right guard Alex Boone and wide receiver Stevie Johnson.

Among those who stretched but did not take part in team drills were defensive tackle Justin Smith, nose tackle Ian Williams and cornerbacks Chris Culliver and Jimmie Ward.

Right tackle Anthony Davis, who's coming off shoulder surgery, worked out on a treadmill in the weight room while wearing a New Jersey Devils sweater. Offensive tackle Jonathan Martin observed practice but did not participate, meaning more reps for Adam Snyder and Ryan Seymour at right tackle.

Gore's absence is not tied to a contract dispute -- he's entering the final season of a three-year extension -- and instead he was merely getting rest, a league source said. Gore has participated in morning workouts previously this offseason.

With Gore out, the running back duties were handled by Kendall Hunter, LaMichael James, Jewel Hampton and Marcus Lattimore, who missed last season recovering from knee surgery. Rookie Carlos Hyde, a second-round draft pick, missed practice to fly to this weekend's NFL Players' Association rookie photo shoot in Los Angeles.

Cornerback Eric Wright appeared to tweak his right ankle early in practice and headed to the locker room. Cornerback Chris Cook and Tramaine Brock saw time with the first-string defense, with Perrish Cox resuming his role covering the slot receiver.

Boone reportedly is skipping at least the start of OTAs in search of an extension to his contract that runs through 2015. Joe Looney saw time on the first unit at right guard, and Vance McDonald filled in for Davis at tight end.

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