RODALE NEWS, EMMAUS, PA—In 2006, a United Nations report raised some eyebrows when it found that cow flatulence accounts for more greenhouse-gas emissions than all the tailpipe emissions from the transportation sector combined. The report blamed issues associated with industrialized operations—things like cutting down rain forests for grazing land; feeding cows an unnatural diet of corn and soy that creates excess, methane-laced cow flatulence; and massive pools of liquid manure that accumulate in huge, factorylike production systems. A 2009 study out of the University of California–Davis put the number closer to 3 percent, but no matter which way you look at it, your cup of milk could be a significant source of pollution. To figure out which farming systems are more sustainable than others, a new report looking at four scenarios finds that grass-based, organic dairy farmers operate much more lightly on the planet, while often producing milk that's healthier for people. It's better for cows, too: They live significantly longer and under better conditions than chemical-based dairy operations.
Your body will thank you, too. Harvard researchers found that grass-fed dairy cows produce milk that's much higher in conjugated linoleic acic, or CLA.. In the study, people with the highest levels of CLA in their tissue touted a 36 percent lower risk for heart attacks when compared with people to with the lowest levels. Plus, you're drinking milk free of growth hormone and antibiotics.
THE DETAILS: Charles Benbrook, PhD, chief scientist of The Organic Center and former executive director of the board on agriculture of the National Academy of Sciences, led the study that investigated four scenarios looking at milk and meat production and money earned, feed intake, land and chemicals needed to produce feed, as well as the amount of waste generated.
Here are the four different types of farm models they analyzed:
1. Industrial production—Holstein cows (the black and white ones) are given genetically engineered growth hormone and other hormones when artificially inseminated (they're not bred naturally). These cows don't live as long as others in the study and are pushed to produce milk beyond their genetic ability. Their diet consists of corn and soy, two things cows were not meant to eat—they make cows gassy.
2. Conventional farm—Holstein cows in this scenario are less intensely managed than in the above factory-farm model, and although conventional, still do feed some grains to the cows, though they also eat more forage-based feeds.
3. Intensely managed organic—Holstein cows are fed grains, but are also required under organic-certification standards to eat natural grass-based foods, too, and to have access to pasture. They are under less stress because they are allowed a somewhat natural diet, and they live longer than cows in the previous two scenarios.
4. Jersey dairy (smaller and light brown) cows raised in an organic, pasture-based system that produce up to 30 pounds less of milk per cow per day, compared to the factory-farm scenario. But the cows live longer in dramatically healthier conditions, making farming more profitable in the long run. And the milk boasts significantly higher levels of beneficial omega-3 fatty acids. No hormones are given, and the cows' main diet is natural, not corn and soy.
Here are some main points from the study:
• Organic dairy-farming systems promote cow health and longevity by placing less stress on cows and feeding them healthier forage-based diets, while also improving the nutritional quality of the milk produced.
• Because cows live and produce milk longer on organic farms, milk cow replacement rates are 30 to 46 percent lower, reducing the feed required and wastes generated by heifers being raised as replacement animals.
• The average organic dairy cow lives several years longer than conventional and industrial cows.
• Organic cows reproduce more easily.
• The manure-management systems common on most organic farms reduce manure methane emissions by 60 to 80 percent; enteric methane emissions (animal belching and farting) are significantly reduced.
Published on: November 10, 2010
Updated on: November 12, 2010