If you regularly buy 'cage-free' eggs instead of the conventional kind, you are off to a good start in supporting the welfare of farm animals, according to the World Society for the Protection of Animals (WSPA) and reported by Christian Science Monitor.

The same goes for buying 'free-range' poultry and 'grass-fed' dairy and meat although those products may be harder to find, a recent survey by the WSPA concludes. Even scarcer: meat, dairy, and eggs verified by an independent third party as humanely raised.

Marketers have caught on to the demand for humanely raised foods, using labels such as 'cage-free', 'no antibiotics used' and 'no hormones administered'. The trouble with these labels is that, even if the claims are substantiated, they only cover one aspect of production. In some cases, labels are redundant: 'no hormones administered' is not necessary on poultry, for example, since hormones are prohibited in poultry production.

In an effort to clear up the confusion that can surround various humane claims on foods, WSPA first categorized different labels as either 'good', 'better' or 'best' and then surveyed their availability in the nation's top 23 supermarket chains. The greatest selection was found at Whole Foods, while one of that store's competitors, Trader Joe's, tied for ninth place out of the 23 chains.

"It was very interesting, even for our staff," notes Sharanya Prasad, program officer of the WSPA-USA, "like in the case of Trader Joe's, where we didn't find so many options, whereas we were quite surprised that we found options in some of the other chains."

Consumers can sign petitions to demand more humane choices on WSPA's web site. The subject of the current petition is Trader Joe's. The company declined to comment.

"A majority of the public indicate that they want to be able to make that choice [to buy humanely raised foods], and decisions such as that can make a profound impact on the lives of animals that are raised for food," says Ms Prasad, citing two 2007 opinion surveys – one conducted by WSPA and one by Oklahoma State University, showing that 68 percent and 49 percent of respondents, respectively, felt concern for farm animal welfare.

Some animal scientists maintain that, in general, the animal agriculture industry is not intentionally inhumane.

"You see these things like PETA shows, with the dairy cows at the slaughterhouse and the pigs being kicked. That's not our standards," says Debbie Cherney, associate professor of animal science at Cornell University in Ithaca, New York state. "Those are the bottom-feeders."

But any amount of maltreatment that goes on in meat and dairy production is unacceptable, Dr Cherney says. "We can have a humane, sustainable system, even in light of rising food prices and more people in the world to feed."

In fact, meat production cannot be sustainable without maintaining humane standards, so long as science is carefully applied to the definition of 'humane', she says.

Certain standards, such as those pertaining to confinement and the ban of antibiotic treatments, for example, don't enter into the humane question. WSPA agrees, saying that 'natural' and 'organic' labels have no bearing on humane conditions.

"There's an entire scientific field designed to look at various aspects of behavior, and physiology, and production, to try to optimize production systems," says Joy Mench, animal science professor at the University of California, Davis. She explains that it takes a delicate balance of health, behavioural, and economic considerations to achieve humane conditions for domesticated animals being raised for food.

"The trick," Dr Mench says, "is to figure out what behaviours are important and that animals really want strongly to perform regardless of the circumstances they're in." For example, according to Certified Humane labelling program, chickens do not need access to the outdoors but they do require nest boxes and are not allowed to be caged. Basically, 'cage-free' is essential to chicken welfare, whereas a farm can easily shut its door on 'free-range' if that standard becomes unsustainable economically.

'Free-range' and 'cage-free' claims only go so deep. Because Certified Humane and other independent, scientifically reviewed labelling programs, such as American Humane Certified and Animal Welfare Approved, actively review multiple factors related to safety and health of animals, their labels are a better indication of humane conditions than any single-claim label.

These three organizations are accredited as certifiers by the Agriculture Marketing Service (AMS) of the USDA. "Our charge is to facilitate the marketing of products," says Craig Morris, AMS deputy administrator, "and we want to help consumers make sure that they get the kind of products that they're expecting, that the animals are treated the way they expect them to be treated."

Ms Prasad anticipates future collaboration with AMS on the part of the three humane labelling groups, hoping that national standards can be set, and a single label be overseen by AMS, as has been done with the National Organic Program.

"Farmers will produce the food that is most in demand," Ms Prasad reasons, "and although, currently, prices for humane products are higher, if there is a demand – as the survey indicates – they will become much more competitive with conventionally raised animals in factory-farm situations."

"We can't do it any other way," adds Dr Cherney to Christian Science Monitor. "If an animal is not comfortable, if an animal is in distress, [then] they aren't going to be producing at their maximum."