No wonder Donkey and Puss in Boots get pushed aside in Shrek the Third. Way must be made for awfully big bull — namely the stodgy story’s inability to walk the talk of its final message.

Suggesting our deeds, hearts and words define personality — not taunting slams of those who insist we’re dorky losers, or, in Shrek’s case, an evil ogre — isn’t a problem. (Although, unlike Spanish verb tenses or calculus formulas, it didn’t need so much repetition to sink in.)

It’s that very little is surprising, touching or funny about the deeds, heart or words of this third go-round. Safely and sluggishly, Shrek the Third behaves like what it’s been told it is — life (or retail) support for a cash cow.

Granted, any movie that pays such close attention to a gingerbread man’s tortured psyche will have several smirks, and the astounding visuals are crisp enough to pick out Shrek’s flecks of stubble. Still, the movie substitutes the gleeful fun of the first two for something every bit as humdrum and homogenous as the films called out by the charming insolence of the 2001 original.

The industry of ironic fairytales spawned by Shrek further makes it suffer by comparison. Prince Charming (voiced by Rupert Everett) might have hatched his revenge plot after renting Happily N’Ever After. In Shrek 2, the green ogre (Mike Myers) foiled that vainglorious worm’s bid to marry Princess Fiona (Cameron Diaz) and reign over the fairytale land of Far, Far Away.

Charming now presents his revisionist-history take to a less-than-receptive dinner-theater crowd. Finally unable to take it anymore, he visits a tavern, caters to the brooding anger of fairytale villains (Captain Hook, the Headless Horseman, Rumplestiltskin) and plots a coup of the kingdom.

Meanwhile, Fiona’s father, frog king Harold (John Cleese), is on his death-pad, and Shrek dislikes putting on royal airs in his in-law’s place. Before Harold croaks, he asks Shrek to succeed him. (Why Queen Lillian, voiced by Julie Andrews, can’t rule as a monarch is never considered.) Shrek begs off and instead agrees to seek out Harold’s long-lost cousin Artie, the next next in line.

Shrek sets sail with pals Donkey (Eddie Murphy) and Puss in Boots (Antonio Banderas), but not before learning Fiona is pregnant. Reluctant to raise ogre children with exponentially greater capacity for poop and tears, Shrek suffers literal nightmares in which he’s beset by baby broods.

Plus, it turns out Artie (Justin Timberlake) isn’t king material. He’s a high-school twerp so meek that his tormentors are a “D&D” brace-face and a kid whose nose bleeds when he snorts. Eventually, the quartet gets lost on its way home, where Fiona, Lillian and fairytale-princess ladies in waiting plan retaliation from underground while Charming’s crew pillages and plunders above.

Shrek the Third offers more dazzlingly detailed animation than its predecessors, but this most cinematic installment has a script barely worthy of straight-to-DVD. Rather than firing another barrage of unnecessary new characters, the movie should’ve junked the Artie storyline and seen Shrek and Fiona cope with leadership roles and pending parenthood before Charming’s revenge.

There’s nothing interesting at all about Artie, unless you consider what once was a can’t-miss promotional tie-in before Timberlake and Diaz dissolved their real-life relationship. Instead, Artie distracts from everyone we’ve come to love, namely Puss and Donkey. Save for a fun body-swapping gag courtesy of addle-brained magician Merlin (Eric Idle), they’re marginalized.

One plus to Shrek the Third is that most of the jokes that work abandon easy, empty pop-culture references (except a chuckle-worthy bit with Merlin playing “That’s What Friends Are For”).

Gum-cracking girls at Artie’s Worcestershire High School alternate modern slang and Middle English. Pinocchio further fudges facts to prevent his nose from growing. And evil, enchanted trees lament how hard it is to branch out. None is a belly laugh, though, and it’s clear that with this patchy entry, the series has jumped the Shrek.