Production efficiency cited as one key to reducing dairy’s carbon footprint.
By Dave Natzke
Proponents of dairy technology and sustainability have a new arrow in their quiver. On June 30, the Proceedings of the National Academy of Sciences web site published a Cornell University study demonstrating the use of recombinant bovine somatotropin (rbST) reduces the carbon footprint of milk production.
The study, “The Environmental Impact of Recombinant Bovine Somatotropin (rbST) use in Dairy Production,” is authored by Cornell professor Dale Bauman, post-doctoral research associates Jude Capper and Euridice Castandena-Gutierrez, and Monsanto scientist and Cornell alumnus Roger Cady.
With modern agricultural practices – especially those related to livestock production – coming under increasing pressure, the entire dairy industry is seeking ways to become more “sustainable” and reduce its overall carbon footprint. For example, spearheaded by Dairy Management Inc., producers, processors and marketers recently held a “Sustainability Summit” to address issues from the farm to the consumer (see July 2008 Midwest DairyBusiness, “Make Dairy Industry More ‘Sustainable’,” by Paul Rovey).
However, frequently lost in the rush toward “sustainability” is the need for adequate food production to feed a growing population, and the need for food producers to achieve adequate profitability to stay in business.
According to the Cornell study, as the global population reaches 9 billion people in the first half of the 21st century, the food supply required over the next 40 years will approximately equal the total amount of food produced throughout the history of humankind. U.S. milk production will have to increase to 5.62 billion gallons by 2040 to meet USDA dietary recommendations for three 8-oz. glasses of milk per person each day. The most sustainable way to increase U.S. milk production is to improve production per cow, and assess total population environmental impact per unit of milk produced.
“Sustainability is important in agricultural production, with an emphasis placed on meeting human food requirements while mitigating environmental impact,” said Bauman. “This study demonstrates that use of rbST markedly improves the efficiency of milk production, mitigates environmental impact including greenhouse gas emissions and reduces natural resource requirements such as fossil fuel, water and land use.”
The study design included three models to predict the environmental impact of using rbST:
1. one examined the impact of increased productive efficiency of individual cows in a producer’s herd.
2. another examined industry-scale adoption of rbST-supplemented cows, a number equal to approximately 15% of the current U.S. dairy herd.
3. another examined the environmental impact of achieving future increases in the future U.S. milk supply required to meet projected population growth and USDA Dietary Guidelines using conventional, conventional with rbST or organic production systems.
Increasing milk production efficiency reduces the feed required per unit of milk by diluting the fixed maintenance feed requirements over more units of milk. This means less manure is produced per unit of milk, and the amount of nitrogen and phosphorus that could potentially run off into waterways is reduced.
The carbon footprint will also decrease when the same milk can be produced with fewer animals and less crop production. “The total reduction in the carbon footprint conferred by rbST supplementation of 1 million dairy cows is equivalent to removing approximately 400,000 family cars from the road, or planting 300 million trees,” the study’s authors said. “Increased milk production efficiency also decreases the energy needed from fossil fuels and electricity required for cropping and milk production.
“The savings in gasoline alone would be sufficient to power approximately 1,550 passenger cars, each traveling an average of 12,500 miles. Further, the total fossil fuel and electricity savings would provide sufficient annual heat and electricity for approximately 16,000 and 15,000 households, respectively.”
More cows are needed to meet projected dietary demand, but with technologies and husbandry practices that increase productive efficiency, that need can be greatly reduced. The authors report that 8% fewer cows are needed in an rbST- supplemented population, whereas organic production systems would require a 25% increase to meet future production targets.