Life-Cycle Studies: Milk
For the past five years, Worldwatch has explored the history, production method, and environmental and social impacts of everyday products – from chopsticks to pencils – in the Life-Cycle Studies section of its bi-monthly magazine, World Watch.
Milk has nourished young mammals for millions of years, but only humans skim, shake, “chocolify,” and otherwise alter and commodify the milk of other species. Yet before cattle were domesticated some 9,000 years ago, milking a cow was an extreme sport and humans avoided or just ignored their milk. And after weaning, they had no need for the enzymes that separate lactose sugars, so most older humans were lactose intolerant. But geneticists guess that 5,000-7,000 years ago in Europe a rare adventurous lactose-tolerant individual dared to drink the milk from his or her cattle. Those with similar genetic advantages eventually followed in a similar milky way.
Many of the cultures that first developed tastes for milk, such as the almost entirely lactose-tolerant Scandinavians, continue to drink it the most: The highest annual per-capita milk consumption worldwide is found in Finland (184 liters) and Sweden (146 liters). More than 578 million tons of fresh milk were produced in 2008, a 20-percent increase from 1998, according to the UN Food and Agriculture Organization. China, Brazil, and India accounted for nearly half of the decade’s increased output. The FAO expects that milk consumption will double by 2050.
Like humans, cows must become pregnant to produce milk. Within a calf’s first two days, females are removed and raised for dairy production, while males are often sold for beef. Cows are increasingly living out their lives in concentrated animal feeding operations (CAFOs). In the United States, the largest dairy farms raise an estimated 1,200 cows each, according to the U.S. Government Accountability Office. The GAO estimates that such large farms generate 30,502 tons of manure apiece each year, forming lagoons of waste that often generate runoff water pollution and foul the air with nitrous oxide and other contaminants.
Dairy herds are fed corn or soy to increase daily milk production. However, cows evolved to eat grasses, so a starch-based diet often results in increased physiological stress and infections, which producers typically minimize through multiple antibiotic injections every year. Larger operations treat herds with pesticides to prevent irritation from flies and lice, exposing farm workers and potentially contaminating nearby water resources. Some producers also treat their cows with bovine growth hormone (or rBST), which researchers have linked to calf deformations, udder infections, and cancer risks in milk consumers. While the United States considers rBST health risks to be “manageable,” the hormone is banned in Australia, Canada, most of Europe, and New Zealand. Consumer opposition has led several dairy farms to end rBST use voluntarily; applications in the United States decreased by at least 5 percent since 2002, according to the U..S. Department of Agriculture.
Dairy farms contribute, on average, 93 percent of the greenhouse gas emissions associated with milk (with dairy processing and packaging production responsible for the remaining gases), mostly due to methane released directly from cows and land-use changes associated with creating cow pasture. On average, one kilogram of milk is responsible for one kilogram of carbon dioxide equivalent, according to the International Dairy Federation. The FAO, in a report released in April, estimated that the global dairy sector contributes 4 percent of human-caused greenhouse gases. Each kilogram of milk also requires nearly 10 liters of water for feed, cleaning, and production.
Milk can generally be certified as organic if dairy herds are fed crops (or pasture) free of synthetic fertilizers, pesticides, genetic modification, and slaughter byproducts such as manure or blood. Farmers must also grant herds access to pasture during growing seasons, treat the cows humanely, and separate any sick cows treated with antibiotics.
In addition to organic certification, several governments and industries are rolling out initiatives to limit dairy farm waste, emissions, and water use. The United Kingdom, for instance, announced its Milk Roadmap in 2008 – a voluntary campaign to reduce water usage 5-15 percent per liter of milk by 2010, develop manure management plans on 95 percent of farms, and reduce dairy-related greenhouse gases 20-30 percent below 1990 levels by 2020.
Link to Worldwatch Institute