Learning how to be a good egg

We were once urged to "go to work on an egg", and they are now being touted as the ultimate fast food in a huge advertising campaign. But as anyone who shops at a supermarket will know, the bewildering array of different types with apparently healthy credentials and assurances is enough to confuse the most cautious of consumers.

Eggs are a good source of protein and vitamins, including A (for healthy skin and eyes), D (for strong bones) and the stress-fighting B complex. They also contain zinc, which is needed for a healthy immune system, iodine, which is required for a healthy thyroid gland, and a good dose of anaemia-protective iron.

Here, ANGELA DOWDEN presents our guide to the way different types are produced and how healthy they are, both marked out of 10.

Eggs from "Caged Hens"

Welfare: Eighty per cent of hen's eggs come from birds kept in the battery system - cramped cages in rows or tiers. The cages have sloping wire floors (through which manure passes), feed troughs and drinking spouts. Hens kept more than four per cage have as little as 450cm2 to live in - about three-quarters of the area of an A4 size of paper. They can't flap their wings and may suffer from weak or broken bones through being forced to produce eggs so intensively. One plus point is that debeaking has recently been phased out as a routine practice in caged hens. 2/10

Health: Though the hens have a miserable life, their eggs are nutritious, largely because of supplemented feeds given with scientific precision. Caged hen eggs with the Lion symbol are the type to look for if you are using the eggs raw - those flocks have been vaccinated against salmonella. 6/10

Total: 8/20

Deep Litter Eggs

Welfare: Hens producing these eggs are kept at a maximum stocking density of up to seven hens per square metre of floor space. At least a third of the floor area is covered with a litter such as straw, wood shavings, sand or turf. The hens have freedom to move within the house, but in large colonies there may be feather pecking or cannibalism, which requires the hens to have their beaks partially removed. 3/10

Health: Nutritionally, deep litter eggs are the same as battery eggs. Disease is likely to be more rife than among caged eggs though (as the hens aren't kept apart), which may mean more prescribed drugs. Though in theory there is a clear-out period during which eggs can't be sold, there is a possibility of eggs with chemical traces reaching the food chain. 5/10

Total: 8/20

Barn eggs

Welfare: Also known as Perchery Eggs, these come from hens crammed in at up to 25 hens per square metre of floor space - but with access to perches of sufficient length to ensure at least 15cm of space per hen. The birds have more freedom to move within the house, but hens can be injured by falling between levels or flying into perches. Risk of feather pecking and cannibalism is high, meaning beak trimming is often necessary. 2/10

Health: Same as for Deep Litter Eggs. 5/10

Total: 7/20

Semi-Intensive Eggs

Welfare: Semi-intensive eggs are produced using either deep litter or barn egg production, but the hens also have access to open-air runs. This sounds great in theory, but breeds not used to venturing outside may end up living in even more crowded conditions inside because the allowed stocking density (2.5 square metres per hen) is calculated according to the area of hen house and pasture combined. 4/10

Health: Same as for Deep Litter Eggs 5/10

Total: 9/20

Free-range Eggs

Welfare: The minimum requirements are the same as for semiintensive, but with the maximum stocking density being lower (one hen per 10 square metres). Birds have access to a different food source (the pasture) and are able to express more natural behaviour.

In the worst-cases, birds are kept in really large flocks, which means almost mandatory debeaking. They don't have access to outdoors at night and can be kept tightly crammed then. At the other end of the scale, smallscale free-range producers keep their hens in excellent conditions with plenty of space at all times. 4/10 (up to 10/10)