In the face of increasing concerns over the controversial use of antibiotic growth promoters in animal feed, agricultural researchers in China are trying to find possible replacements and reduce the need for antibiotics in factory farming.

It is common knowledge that bacteria can become resistant to antibiotics through overexposure. Ordinary people may be cautious when they take antibiotics to treat infections, but few realize that the animals from which our meat and dairy come are usually fed an abundance of antibiotics.

In fact, about half of the antibiotics used worldwide are given to farm animals, largely used at a sub therapeutic level to fatten them or to guard against infections that can spread through barns and pens, according to the World Health Organization.

Tong Jianming, a professor with the Institute of Animal Science under the Chinese Academy of Agricultural Sciences, said Chinese researchers have already focused attention on the potential hazards of antibiotic growth promoters, which speed pigs, poultry and cattle to market but also speed the development of bacteria that are resistant to antibiotics.

Tong is now presiding over a national research project developing and utilizing naturally occurring molecules such as bacteriocins, antimicrobial peptides and enzymes, which may serve as possible replacements for antibiotics.

The project, which started in 2000 and is due for completion by the end of the year, has made several breakthroughs, said Tong.

"My team has applied for patents for five products we have developed, and has put them on the market. Practice shows that these biological feed additives have some encouraging effects to promote growth.

"One example is a Beijing-based egg company that introduced microbe preparation as feed additives and phased out antibiotics and chemicals in chicken feed. The 'green' eggs these hens produced had a better taste and organic features, that helped increase the company's sales by 30 percent over the past four years," said Tong.

He said antibiotics had played a significant role in the development of modern animal husbandry. However, the routine low-dosage use of antibiotics on factory farms has been linked to increased incidence of antibiotic resistance.

The dose of aureomycin -- a widely used antibiotic in feed -- has had to be increased by nearly 10 times over the past 50 years.

In the 1950s, the recommended dose of aureomycin was 10-35 milligrams per kilogram of feed, but now the amount is 100-150. In some areas, the dosage is even higher than 150.

Tong said developing non-antibiotic alternatives was an urgent task.

Tong's point was echoed by Dr Pearse Lyons, president of the US-based Alltech Biotechnology Co Ltd, which is also engaged in the research and production of possible replacements for growth-promoting antibiotics.

Lyons said, "People have now paid more attention to feed safety, as what animals eat will go into humans."

Gu Junhua, general engineer with the China National Center for Quality Supervision and Test of Feed under the Ministry of Agriculture, said China is one of the world's major suppliers of animal products. However, most of the country's livestock rearing farms rely heavily on antibiotics, which seriously hamper the export of animal products to countries that set strict restrictions on the use of growth-promoting antibiotics.

(China Daily September 12, 2005)