Animals are housed in sheds the size of five football fields with herd sizes usually between 1000 and 12,000 and sometimes larger.
They are milked by robots two or three times a day for 10 months. The remaining two months of the year they may go outside into feedlots where they eat grain and bonemeal out of conveyors, stand on concrete, and lie in their own faeces and urine.
The only way we can have milk is for cows to be kept pregnant. The process of continual impregnation and lactation stresses cows' bodies so much that an estimated half suffer from mastitis, and many also suffer from foot diseases, causing lameness.
Cows raised intensively are often so sick, exhausted and spent that they are "turned around" every two years, whereas in the wild they can live up to 20 years.
Yet it could well be that the greatest suffering for dairy cows worldwide is the removal, immediately after birth, of their calves so they don't drink their mother's milk. Calving season can be stressful for farmers, who sometimes hear mothers and calves calling each other for days.
The abundant supply of unwanted male calves and female calves surplus to requirements are slaughtered at a few weeks old for meat, or raised for veal.
In many countries veal calves live for four or five months, tethered with chains around their neck in wooden crates.
They cannot turn to stretch their limbs and are fed an all-liquid milk substitute deficient in iron and fibre to produce anaemia, so the flesh becomes pale. If we were to go down the mega-dairying track, how long before our landscapes, as in certain parts of the US, are filled with veal "hutches" where babies, weak, and with compromised immune systems, live out their short, lonely, miserable lives before being bundled off to the slaughterhouse?
Mega-dairies also negatively affect human health and pose severe threats to the environment.
The routine use of antibiotics to control disease spreading among cows living in close proximity is standard practice in these places. They also generate large amounts of manure, which is stored in huge "lakes". Faulty storage can result in pollution seeping into rivers and streams, and even the water table.
People living near mega-farms in the US have reported health problems.
Cutting down trees to make way for mega-dairies releases carbon, and dairying itself releases huge amounts of potent greenhouse gases in the form of methane and nitrous oxide emissions.
The use of economies of scale is at the base of mega-farms. Billions of animals are raised in factory-like conditions to improve productivity for stakeholders and meet consumer demand for animal produce (milk, eggs, meat). The billions of animals kept in these conditions are objectified as units of production instead of living, feeling beings.
This most basic of assumptions - that animals are our private property with no rights of their own - rarely gets challenged, but it should be.
In the meantime, let us steer well clear of US-style intensive dairy farming in New Zealand.
Sandra Kyle is a Hamilton-based teacher and writer. Lynley Tulloch is a lecturer in sustainability education at Waikato University.
