This cow is `organic'. That means that she doesn't eat pesticides, or chicken droppings. What's more, you can buy her milk at Tesco

It is cheap, nutritious and readily available. For most of us, grabbing a carton or a bottle of milk is as automatic as cleaning our teeth. But what do we know about milk, apart from the fact that it comes out of a cow? Bread, sugar, coffee, eggs, meat have all been analysed, chewed over and worried about; but milk is just there - on the shelf, on the doorstep or in the fridge. Up till now, "semi-skimmed" or "skimmed" have been the principal variants on the theme.

Quietly, however, a market is developing for different varieties of milk. Health shops and delicatessens have sold organic milk and cheese for years, but now these products are going mainstream. Safeway, Sainsbury, Tesco and Waitrose have all been selling organic milk for a few years, and organic cheese since March. And the range is expanding. Kelly Murphy of Tesco said that "as this dairy area is definitely growing rapidly, we are now looking into stocking organic butter as well". Sainsbury are also planning to stock ing organic double cream made with Guernsey milk from this October.

Why are consumers choosing the organic option? Probably because it makes you feel virtuous, like cycling to work. In one simple purchase we feel we are buying a boxed set of principles: "protect the environment, protect yourself against chemical residues and protect animal welfare". So says Rachel Rowlands who, with her husband Gareth, farms at Brynllys Borth (the first dairy farm to receive the organic symbol in 1952). It helps that "organic" is not one of those nebulous terms like "farm fresh", "environmentally friendly" or "traditional". To be described as organic, a product must fulfil strict criteria under EC and national law.

What are the benefits to beast and man in choosing an organic pint or a wedge of organic cheddar? Is it really better for us than ordinary milk? Patrick Holden of the Soil Association, the certification body for organic farmers, puts it this way: "You are what you eat, and so are cows. Organic cows are fed on clover and herb-rich pastures full of variety and diversity." To be "organic", 60 per cent of an organic cow's diet must come from forage - grass, hay and silage that have been untreated with herbicides or pesticides, the natural diet of a ruminant. And 80 per cent of that forage must be organically produced. The remaining 20 per cent must come from a specified source: cereal concentrates made within strict guidelines.

Ordinary dairy cows, on the other hand, will not produce their high yields of milk on forage alone. Their intake of concentrates therefore goes up. Organic cows may only eat cereal concentrates, but concentrates fed to conventional cows are likely to include fishmeal and DPM (dried poultry manure). These substances are not permitted in concentrates fed to "organic" cows. So with organic dairy products, at the very least you know what you are getting.

There are also those who argue that organic milk has more flavour than the conventional stuff. The difference is most discernible in cheese. Jane Lindley, marketing manager for Alvis Bros which has recently started supplying four supermarket chains with a mature organic cheddar, certainly believes organic milk gives a different texture and flavour, and says the taste of the cheese varies according to what time of year it is, due to changes in the pasture.

Douglas Campbell of Welsh Organic Foods, which last year won the Soil Association's Dairy Product of the Year award for his Ty'n Grug organic Farmhouse Cheddar, goes further: "In cheese, uniquely, the nature and character of the milk will translate into the nature of cheese."

Another bonus to the pint of organic milk is that it is not that much more expensive than the normal pint. It hovers around the 36p mark, cheaper than an average home delivery price. The Lyecross cheddar is available in most big supermarkets at pounds 3.19 a pound, about the same as a conventional vintage cheddar.

Worries about the "safety" of organic milk will put off some potential buyers, fearing listeria or worse. Pam Best, with her husband Will and family, has a mixed organic farm of 270 acres in Dorset. She reckons the hardest fight for the organic industry is getting away from a consumer's perception that "organic means something to do with brown bread, sandals and bugs". Misconceptions about "bugs" are quashed by the fact that organic regulations are extremely strict and are on top of standard health and safety rules.

We also fret about the risk of pharmaceutical and pesticide residues in our food. Pesticides are obviously less likely to be present in organically produced dairy products. But so are pharmaceutical residues. In conventional dairy herds, higher-yielding cows require higher levels of medication; resistance to disease can be low. For example, they are treated routinely with antibiotics in the udder during the two months of the year when they are not milked.

This procedure is banned for organic production. An organic cow will only be given antibiotic or other drugs to prevent suffering when they are sick, and then the consumer is protected through extended withdrawal periods, during which the milk cannot be sold as organic. The really telling fact is that organic dairy farmers have extremely low veterinary bills.

Last but not least of the arguments for organic milk is the approach to animal welfare. The system upholds simple respect between man and beast. It is not just that new standards prevent the export of organic calves to continental veal crates. Organic guidelines insist that calves are not weaned before nine weeks and also prohibit over-production of milk. A dairy cow 200 years ago would have produced about 1,000 litres of milk a year. Cows' udders used to be barely visible. The modern super- cow now produces 10 times more.

John Webster, professor of animal husbandry at the University of Bristol, has calculated that the work of a typical dairy cow is exceeded only (in human terms) by cyclists in the Tour de France. But, unlike the cow, the cyclists do not have to sustain this for months on end. After two to three 10-month lactations, the young bovine mothers are often so worn out they are sent to the abattoir. In contrast, Dougal Campbell's organic cows give an average yield of 4,500 litres; some are 13 years old, still being milked and "healthy in body and mind".

At present, there are only 784 organic farms in Britain. In Austria there are 20,000 and farmers are converting to organic methods en masse, in groups of 700-800 at a time. One of the reasons why we lag behind continental Europe in organic farms is the less than generous grants. Here, an overall total of pounds 250 over five years is the maximum amount per hectare a farmer can receive to convert to organic farming. Compare this with Denmark, where organic dairy farmers receive an annual payment of pounds 117 per hectare. The Danish equivalent of our Ministry of Agriculture hopes by the year 2000 to have 25 per cent of Danish milk as organic. A spokesman said: "We are sending organic information into all Danish schools and are paying for research and development into organic food processing." MAFF, please take note.

However, it is not government intervention but consumer demand that will determine whether the organic cow survives to graze into the 21st century. So next time you are buying milk or cheese at the supermarket, toss the worthy option into your trolley. It costs only a few pence more. And who knows? It could only be a matter of time before "real" milk becomes as familiar to the British shopper as wholemeal bread.

Recommended reading: Organic Farming by Nicholas Lampkin (Farming Press, pounds 17.99); Animal Welfare by Professor John Webster (pounds 17.99)

Where to get regular supplies of organic milk and cheese

Organic milk and cheddar cheese are sold in branches of Tesco, Sainsbury's, Safeway and Waitrose.

Choice Organics (0171-924 1744) Will deliver organic milk, cheese, butter and yoghurts in London and the South-east. Will also deliver organic fruit and vegetables. Ring for catalogue.

The Farmers' Dairy Company (01293 612941) supplies organic milk and dairy products from the Bests and the Jones Family of Hertfordshire to Waitrose, Safeway, Budgens and many smaller outlets (01293 612941).

Neal's Yard Dairy, 14 Neal's Yard, London WC2 (0171-379 7646) stocks an organic cheddar among its cheeses. Ring for a mail-order catalogue

Rachel's Dairy, Aberystwyth, Dyfed (01970 625805) supplies organic yoghurts to the main supermarkets, plus smaller ones nationwide.

Welsh Organic Foods, Lampeter, Dyfed (01570 422772) supplies Pencarrey (Welsh version of brie) to Sainsbury, plus a range of organic cheeses locally. Will also send cheeses by mail-order; ring for a price-list and newsletter.

For details of other organic stockists, contact: The Soil Association Ltd (0117 9290661).

We asked shoppers: would you buy organic milk?

Karen Bartlett, 38, full-time mother "I wasn't aware until recently that there was organic milk and cheese. I buy the milk for my two-year-old daughter, Jodie - she calls it her `special' milk. It must have more goodness in it and less processing is good. The only thing that deters you is the cost. I buy vegetarian cheese, but organic cheese is more expensive - but it's good and the flavour is so strong that you don't need so much in cooking."

Vanda Harvey, 38, artist "No, I don't buy it, but that's because I don't know anything about it. Presumably it's from cows that aren't forced to produce large amounts of milk."

Margaret Scott, 76, retired "I've started to buy it because I'm not happy with what's being sprayed on the fields and for animal welfare reasons. I like the organic cheddar."

Roger Stone, 54, gardener "I wouldn't know what it was, though it's probably from cows not in battery conditions. I know that organic chicken is free-range. Mind you, not if you buy eggs from Ned. Old Ned only keeps half a dozen chickens in his garden, but he sells an awful lot of eggs. He buys them in. All his customers believe they're buying free-range. But going back to organic milk, I should think the cows' dung would be used in the fields rather than fertiliser."

Carol Guppy, 31, full-time mother "No, I wouldn't buy it unless I was made aware of terrible cruelty or hormonal injections. If I found ordinary milk was unhealthy or animals were maltreated, then it might be an issue. If I was confronted with organic milk in a supermarket, I'd probably think it was expensive and an unnecessary luxury, a bit like organic veg: nice to have but not essential. With organic meat there's been an issue of taste and quality - but milk just tastes like milk and butter's not going to taste any different."

Edward Kennedy, 28, piano dealer "It sounds wonderful. Can I get it at Tesco's?"