Experts have warned of environmental pollution from increased animal husbandry, as the country became the world's top meat and egg producer last year.

"Domestic animal and poultry waste has become a major source of environmental pollution," Oriental Outlook Weekly quoted Wu Weixiang, associate professor with Zhejiang University's College of Agriculture, as saying in its latest issue.

Wu said animal husbandry in China produces 2.7 billion tons of animal and poultry waste every year, 3.4 times its industrial solid waste.

According to Cheng Xu, a professor at the China Agricultural University, the nation has more than 20,000 large and medium-sized livestock farms, but only 3 percent are equipped with waste treatment facilities.

Cheng said China had introduced a large number of modern livestock breeding systems since the 1970s, which had alleviated the shortage of meat, eggs and milk.

However, most of these modern farms are located near cities and emit untreated animal and poultry waste, which pollute the air and water.

A recent survey by Tsinghua University found agricultural production respectively accounted for 70, 60 and 35 percent of the nutrients (such as nitrogen and phosphorus) in China's three most polluted lakes Dianchi Lake in Yunnan Province, Chaohu Lake in Anhui Province and Taihu Lake in Jiangsu Province.

Cheng said animal and poultry waste made up a large part of the nutrients.

Henning Steinfeld, a coordinator at the Food and Agriculture Organization of the United Nations, said animal husbandry had become one of the most important factors in global environmental pollution.

"The breeding industry now produces even more greenhouse gas than transportation sectors," the weekly quoted Steinfeld as saying in a December forum in Hangzhou.

He said excessive development of livestock husbandry would threaten not only the environment but also the health of human beings.

(China Daily March 3, 2007)