An expert on animal nutrition on Sunday dismissed a Web report that said chickens used by KFC and McDonald's "grow too fast".

Ce.cn, an economic news website, claimed birds at Suhai Group, a large processing company in Shanxi province, grow to full size in 45 days.

In the report on Friday, unnamed workers were quoted as saying they are made to feed the chickens additives and medicine that are "hazardous to humans", and said the company supplies large supermarkets as well as KFC and McDonald's.

However, Hou Shuisheng, an animal nutrition professor with the Chinese Academy of Agricultural Sciences, told China Daily that such a growth rate is perfectly safe and simply the result of successful animal husbandry.

"The growth is attributed to the breed of chickens and artificial feeds, not because of growth hormones, which are banned in China," he said. "Some breeds of white-feathered chickens in the United States can weigh 2 kg after 42 days."

White-feathered chickens, which are mostly imported from the US, account for about 50 percent of the chicken market in China, with the rest made up of domestic breeds, he said.

Suhai Group on Saturday also released an online statement saying it had met standards on feed processing, chicken raising and slaughtering during random checks by authorities this year.

Meanwhile, a manager at a KFC in Beijing's Chaoyang district who gave his name only as Feng said on Sunday that all of the restaurant's chicken is supplied by "qualified manufacturers in Shandong province, not Shanxi".

"Business has been as usual, and there's been no decline in sales since the report," he added.

KFC Corp posted a statement on the micro-blogging website Sina Weibo that said only about 1 percent of its chickens are supplied by Suhai Group, and those that they receive pass quality checks.

McDonald's also said on Sina Weibo that Suhai Group is not its current supplier.

jinzhu@chinadaily.com.cn