Super Chicken strutted a step closer to the dinner table Thursday.

The U.S. government said it will start considering proposals to sell genetically engineered animals as food, a move that could lead to faster-growing fish, cattle that can resist mad cow disease, or perhaps heart-healthier eggs laid by a new breed of chicken.

The Food and Drug Administration issued a proposed legal framework for how it would resolve such questions as whether the altered animals are safe for human consumption and pose no serious environmental risks.

FDA officials said they are focusing on animals that will be used as food, or to produce medications that would then be consumed by people or other animals. The agency is not interested in reviewing genetically engineered mice already widely used in lab experiments.

"Genetic engineering of animals is here and has been here for some time, " said Larisa Rudenko, a science policy adviser with the FDA's veterinary medicine centre. "We intend to provide a rigorous, risk-based regulatory path for developers to follow to help ensure public health and the health of animals."

Canada does not allow genetically engineered animals to be used in food, feed or released in the environment without approval from federal authorities, Health Canada spokesperson Stéphane Shank said in an e-mail.

Reaction from consumer groups was mixed. On one hand, they welcomed the government's decision to regulate genetically altered animals. But they cautioned that many crucial details remain to be spelled out. For example, the FDA does not plan to require in all cases that genetically engineered meat, poultry and fish be labelled as such for consumers.

Pigs with mouse genes?

"They are talking about pigs that are going to have mouse genes in them, and this is not going to be labelled?" said Jean Halloran, director of food policy for Consumers Union. "We are close to speechless on this."

Nonetheless, Gregory Jaffe, who heads the biotechnology project at the Center for Science in the Public Interest called the FDA action a "good first step."

"This is the first time the federal government is announcing a comprehensive regulatory system that addresses the concerns from these animals," said Jaffe. "But it may not have addressed all the environmental concerns."

Genetically engineered animals are not clones, which the FDA has already said are safe to eat. While clones are exact copies of an animal, genetically engineered animals are manipulated by scientists to bring about a change in their characteristics. In years past, this was done by breeding animals with desirable traits. But now the changes can be made directly in the lab.

Genetically engineered animals are created when scientists insert a gene from one species of animal into the DNA of another animal to reprogram some of its characteristics. For example, fish could be made to grow faster, or pigs might be re-engineered to produce less waste. Animals can also be engineered to produce substances in their milk and blood that can later be used for human drugs.

Genetic engineering is already widely used in agriculture to produce higher-yielding or disease-resistant crops. But it's unclear how consumers will react to altered animals, even if they come with a government seal of approval.