Grocery shoppers are often bombarded with confusing egg carton claims, including 'cage free', 'free range' and 'pastured', reports Star Tribune from Minneapolis and St Paul in Minnesota. "Does the degree to which a hen is confined affect the quality of its eggs - and our health?" asks the newspaper.

Even if you do not care about chickens' rights or have an opinion about the flavour or nutritional merits of the free-range eggs, buy something more produced locally whenever possible. Saving a buck to keep a giant farm in the Central Valley of California in business does nothing for our local economy, other than keeping a dollar in your own pocket.

Decoding Labels

Buying eggs at the grocery store used to involve one step: Flip open a carton to check for cracks. Now there is a multitude of choices: there is 'cage-free', 'free-range' and 'pastured'. There is a range of prices, health claims and even shell colors. Labels can be confusing or nebulous: does 'organic' mean 'free-range'? Why does any of this matter?

Getting straight answers is about as easy as whipping a fluffy meringue by hand.

Usually, the cheapest option is a conventional egg, which means it was probably produced at a large commercial operation with thousands or even more than one million hens. Hens are typically contained in small cages, called battery cages, and cannot spread their wings. Lighting might be controlled to regulate egg production, and hens are fed a corn, grain and soy mix. Proponents say this method is cheap, efficient and good for food safety.

Critics of conventional production say that it is cruel, unnatural and environmentally damaging and that it stresses hens to the point they become sickly and produce less healthy eggs. Last month, California voters passed Proposition 2, which says hens in that state must at least have room to spread their wings. Battery cages in the European Union will be phased out by 2012.

Conventional-cage eggs make up 95 per cent of US egg sales, while 5 per cent are cage-free, which includes free-range and pastured, according to the International Egg Commission's 2008 figures. That is up from 2 per cent cage-free sales in 2000. More consumers are also choosing organic - a designation that means hens have access to a pasture, the outdoors and a comfortable shelter. Although organic poultry and egg sales still represent less than 1 per cent of total sales, organic egg sales alone are expected to rise nearly 40 per cent by the end of the decade, according to the US Department of Agriculture.

Free-range eggs can cost a dollar or two more per dozen but Angel Dobrow of Northfield, Minnesota was more concerned about the health consequences of eating eggs produced under 'inhumane' and 'horrible' conditions. Ms Dobrow buys free-range farm eggs directly from Simple Harvest Farm or the Just Food co-op in Northfield and says that once her family started eating free-range farm eggs, they realized 'They just taste better,' she said. "The proof is in the pudding."

"From a food safety point of view, absolutely, cage-free eggs are much safer," said Dr Michael Greger, director of public health and animal agriculture for the Humane Society of the United States, which supported Proposition 2. Dr Greger said crowded conditions create more faecal dust and opportunity for spreading disease. He pointed to a number of studies that conclude caged egg production increases the risk of salmonella.

However, the American Egg Board, an industry organization funded by producers with more than 75,000 layer chickens, says on its web site, "Most new construction favours the cage system because of its sanitation and efficiency."

Minnesota does not track the manner in which eggs are produced, and Jeff Bender, director for the center for animal health and food safety at the University of Minnesota, says both production methods have advantages and disadvantages. Birds roaming on pastures could pick up microbes from wildlife they encounter outdoors, Dr Bender said, while caged birds in close quarters might spread disease rapidly.

From a nutritional standpoint, conventional eggs are among the least healthy choice, said Mary Jo Forbord, a registered dietitian, farmer and executive director of the Sustainable Farming Association of Minnesota. If battery-caged hens represent one end of the spectrum, 'pastured' hens are the opposite end. These animals are free to walk in the sun, stretch and spread their wings and forage for some of their food, which might include green plants, seeds, insects, worms, vegetables and grains. They are typically raised on smaller farms with flocks in the hundreds or less.

There is a growing body of evidence that pastured or free-range animals are nutritionally superior, Ms Forbord said. Their eggs are packed with higher doses of healthy fats such as conjugated linolenic acid and omega 3, as well as vitamin E and beta-carotene, which converts to vitamin A. "What animals are fed really affects the quality and composition and resulting nutrients of the product," she said.

Kristin Tombers, owner of Clancey's Meats in Minneapolis, said customers often comment on the flavour and freshness of the shop's eggs, which come from small Minnesota farms with unconfined, chemical-free hens. "It's a super bright colour and bright flavour. There's no comparison," she said.

Just as consumers can choose what eggs to buy, producers should be free to raise those eggs in whatever environment they choose, said Mitch Head, spokesman for United Egg Producers, a national farmers' cooperative that represents about 90 per cent of egg producers in the country, including most of the largest producers. That is one of the reasons the group opposed Proposition 2.

"Consumers have those choices in the grocery store today," he told Star Tribune. "They have the choice, so they can vote with their pocketbook every time they go into the store."