Controversial animal rights group People for the Ethical Treatment of Animals (PETA) have fired off a series of fuming letters to actors Adam Sandler, Cher, Rosario Dawson, and Sylvester Stallone over the treatment of animals on the set of their upcoming comedy, The Zookeeper.

The film — currently in pre-production — will star Kevin James as an unlucky-in-love zoo worker, who secretly falls for a co-worker, portrayed by Rosario Dawson. The film will feature a number of exotic animals — voiced by Cher, Sandler, and Stallone — who coach him through his quest for her love.

PETA bosses are furious that Sandler’s Happy Madison production company hired animal trainers from California for the shoot at Franklin Park Zoo in Boston, Massachusetts – claiming the company has a history of neglecting animals. According to PETA, Gary Gero’s Birds & Animals Unlimited has been cited by the US Department of Agriculture for “numerous animal welfare violations.”

“We’re hoping to enlist the film’s stars to keep cruelty off the set. Exotic animals used as involuntary ‘actors’ are routinely subjected to rigorous and abusive training methods to coerce them into performing acts that are stressful, uncomfortable, confusing and even painful,” says PETA spokeswoman Amanda Schinke.

A rep for Gary Gero’s has fired back at PETA, branding the organization irrational and misinformed: “When we did (1989 movie) Batman, PETA said our penguins should have been kept cold, they were from South Africa! They don’t do their research and there’s nothing that can be said to change their minds. We’ve been in the business 45 years, we’re highly respected. We know our animals are well-treated and well-cared for and we can sleep very well at night.”