04/10/2012 11:16 BST | Updated 04/12/2012 05:12 GMT

Cow's Milk is the Cruellest Drink: A Case for the Vegan Option Continued

Milk is only in constant supply if dairy cows give birth to a calf every year. This means they are pregnant for most of their lives. Brought into season with hormones and artificially inseminated they become worn out from producing a hugely unnatural quantity of milk and are usually culled after four or five years of milking, or - in the most intensive systems - two. Their carcases are used for soup or other processed food at the cheap end of the market.

Milk production has grown ever more intensive over the years. In the UK in the 1950s dairy cows produced about 10 litres a day. Now 22 litres is typical with the top-yielding cows producing 30 to 35 litres every day. As a consequence udders have become grotesquely large and when full can weigh 50 kilos and up to 75 kilos for the highest producing cows. These hugely heavy, pendulous, mammary glands drag on udder tissue and press down on the cows' back legs. The discomfort is evident in their unnatural lumbering gait - a huge contrast to cows in suckler herds: they suckle their own calves that take just a few litres at any one time, have udders of a natural size and walk in a distinctly easier - and normal - way.

Producing hugely unnatural quantities of milk has a dire impact on health. Like slimmers on the Atkins diet who use up all their carbohydrate stores and burn fat instead, dairy cows can enter a state called ketosis which means ketones are deposited in the liver. When humans are 'in ketosis' they feel extremely unwell. Since cows in the same condition become ever more depressed and lethargic experts assume they must feel equally ill. The accompanying exhaustion weakens immune systems: infections and ill health follow.

Lameness is another inescapable part of a dairy cow's life. Cows are heavy, and heavier still when they are carrying unborn calves and udders engorged with a vast quantity of milk. The weight bears down on hooves which can crack and split. Laminitis - an inflammation of the sensitive layers of tissue inside the hoof - is excruciatingly painful, particularly if cows have to walk long distances for milking. Sole ulcers are caused when dirt and bacteria get into cracks in the outer rim of feet and abscesses develop. Dermatitis causes extremely painful lesions, also on feet. Surveys show that half the dairy cows in the USA and Europe are lame at some time every year.

Another common disease is mastitis, an infection of the udder and also very painful. Caused by bacteria entering the teat canal, the infected udder becomes swollen, hot to the touch, lumpy, distended and a brown discharge leaks from the teats, rife with pus. Farmers try to reduce cases of mastitis by injecting a long-acting antibiotic into all 4 teats during the 6-8 week 'dry period' - when milking is stopped before cows have their next calf. But cows that have mastitis repeatedly are culled.

The story of calves is no less brutal. They are taken away soon after birth so that their mothers can be returned to the milking parlour as soon as possible. Most female dairy calves are kept to become herd replacements - and the whole brutal cycle begins all over again. Unwanted calves are dispatched - shot or electrocuted. The remainder are usually sold on through markets for rearing as low quality beef or veal and often exported to the Continent. Distraught at being separated from their mothers and made wretched by the trauma of travelling, one in 5 under 2 weeks of age dies within a few weeks of having been passed through a market.

Humans are the only species that drinks milk from another animal or that drink milk throughout adulthood. Supermarkets are abundant with milk products - like cheese, yoghurts, cream. Yet the health benefits are questionable: saturated fats; hormones; overly rich in protein; and implicated as a cause of testicular, breast and prostate cancer and heart disease.

Nevertheless milk consumption increases and milk production becomes ever more intensive. All over the world mega dairies are burgeoning - in the USA, China, Saudi Arabia. In the UK the National Farmers Union is pressing for mega dairies here too. These are zero-grazing systems in which cattle are fed cut grass and never go outside to graze. Tethered by their necks in vast sheds with concrete flooring they are endlessly restless as they try to lie comfortably as their huge weight bears down on pressure points.

Cow's milk (at 25 pence a pint) is cheap. But what is the cost to the cows? They are treated as milk producing machines rather than living, sentient beings. Their management is inhumane, heartless, oppressive and callous - and makes cow's milk the cruellest drink.