THE THEORY that Collingwood pair Lachie Keeffe and Josh Thomas could have eaten beef contaminated by clenbuterol in New Zealand has been rejected by the Kiwi beef industry.

Keeffe and Thomas tested positive to the banned drug several days after returning from a week-long training camp in Queenstown, New Zealand, where they reportedly ate out several times, including a steak meal.

Australian cyclist Michael Rogers was cleared after testing positive to clenbuterol in 2013 when authorities accepted he could have eaten contaminated meat while racing in China two months earlier.

While clenbuterol is used in livestock in some countries, New Zealand beef industry association chairman Bill Falconer was adamant that was not the case in his country.

"It's just not something that has cropped up in New Zealand," Falconer told Radio 3AW.

"Obviously you can read stuff to say that there had been rumours of it happening in China and Spain but not in New Zealand."

Former ASADA head Richard Ings also dismissed the possibility.

"Clenbuterol is not present in the Australian food chain. It is not present in the New Zealand food chain, it has occurred in China and Mexico but it is not an issue here," Ings told 3AW.

"So the players will need to find the right explanation where this clenbuterol came from.

"It's a veterinary drug in Australia, it's a veterinary drug in New Zealand; it's only approved for use in racehorses.

"But as with all these performance enhancing drugs you can get it online and there is a person at the back of some gyms that will sell it to you. It is commonly abused in bodybuilding and other sporting activities."

Keeffe and Thomas have denied knowingly taking the drug and have sought independent legal advice through the AFL Players' Association.

Collingwood coach Nathan Buckley said the entire squad had eaten out while in New Zealand.

"I'm not a scientist. I haven't done a lot of study in the area," he said. 

"All our boys ate out. We had a couple of team dinners. One happened to be a steak dinner, but I don't know about the efficacy of the possibility of the substance coming from something that was ingested. 

"We've gone through what we've provided the players and there's no doubt at all that the internal environment here and what we've provided to our players has been beyond reproach."