They say that resistance to antibiotic drugs is a growing health crisis, fuelled by widespread overuse of antibiotics in both agriculture and in human medicine.

And they add that leading health experts and scientific bodies agree that nontherapeutic use of antibiotics in animal agriculture leads to antibiotic-resistant infections in humans.

In their statement the farmers said: "As American farmers and ranchers raising beef cattle, dairy cattle, pigs, and poultry, we are doing our part to address this crisis by avoiding unnecessary uses of antibiotics on our farms and ranches.

"We believe the imprudent use of antibiotics not only renders antibiotics less effective or ineffective for sick farm animals, it also threatens public health and the safety of our nation's food supply.

"We are concerned for the health of our customers, our neighbors, our employees, and our own families."

The farming group says that their farms and ranches demonstrate that it is possible to protect public health and offer Americans a steady supply of food.

And they show that it is not only possible but actually economically viable to produce meat, dairy products, and eggs that are safe to eat without continually dosing animals with drugs they do not need.

Their petition is backed by hundreds of scientists, who have also issued a statement saying that scientific research studies and analyses by international scientific bodies support the conclusion that the overuse of critical human drugs in food animal production is linked to human diseases increasingly impervious to antibiotic treatment, putting human lives at unnecessary risk.

"The use of antibiotics for whatever purpose over time creates drug?resistant strains of bacteria, thwarting successful treatment of infectious diseases. So, antibiotics should be used only when necessary," the scientists say.

"Despite wide acceptance of this principle, antibiotics are still routinely added in enormous quantities to the feed and water of most livestock and poultry-not to treat disease, but to promote faster animal growth and stave off diseases caused by poor diets and by raising animals in overcrowded, unsanitary living conditions."

The two groups say that the problem of antibiotic overuse is enormous.

They add that recent Food and Drug Administration (FDA) data show that nearly 80 per cent of all antibiotics sold in the United States are used in animal agriculture.

"The majority of these drugs-many of which are critical in both animal and human medicine-are routinely given to livestock and poultry that are not sick. This is done not to treat disease, but to promote faster animal growth."