By Sarah Muirhead
June 6, 2009
U.S. population’s requirements for dairy products is best fulfilled and most sustainable through the application of modern agricultural techniques rather than those of past decades.
Contrary to the negative image often associated with large farm operations, the U.S. population’s requirements for dairy products is best fulfilled and most sustainable through the application of modern agricultural techniques, a just-released study has shown.
The study, conducted by Drs. Jude Capper and Dale Bauman of Cornell University and Roger Cady, formerly of Monsanto and now with Elanco Animal Health, compared the environmental impact of modern (2007) U.S. dairy production with that of dairy systems in 1944.
For the comparison, the researchers used a deterministic model based on the metabolism and nutrient requirements of the dairy herd. The model estimated resource inputs and waste outputs per billion kilograms of milk. Both the modern and historical production systems were modeled using characteristic management practices, herd population dynamics and production data from U.S. dairy farms.
Among the findings were that modern dairy practices require considerably fewer resources than dairying in 1944 with 21% of animals, 23% of feedstuffs, 35% of the water and only 10% of the land required to produce the same 1 billion kg of milk.
Waste outputs were similarly reduced, with modern dairy systems producing 24% of the manure, 43% of CH4 and 56% of N2O per billion kg of milk, compared with equivalent milk from historical dairying.
In 1944, the U.S. dairy population totaled 25.6 million cows producing a total of 53.0 billion kg of milk annually. It was a system characterized by pasture-based systems with rations reliant on home-grown forages with few purchased concentrate feeds. Draft horses powered the majority of agronomical operations, with only 1.2 tractors employed per farm. Inorganic fertilizer use was not yet widespread; instead, animal manure was used to fulfill crop nutrient requirements.
The researchers noted that many of the characteristics of 1944 dairy farming (low-yielding, pasture-based, no antibiotics, inorganic fertilizers, or chemical pesticides) are similar to those of today’s modern organic systems.
By contrast, the researchers said, the 2007 U.S. dairy herd comprised only 9.2 million cows, with an annual milk production of 84.2 billion kg. Typical modern dairy production systems are characterized by the use of total mixed rations formulated to fulfill nutrient requirements, together with herd health and management programs and facilities designed to minimize stress and maximize production. Furthermore, feedstuffs used in modern systems are harvested from high intensity row-crop farming practices, they said.
The carbon footprint per billion kilograms of milk produced in 2007 was found to be 37% of equivalent milk production in 1944.
"The 2007 dairy industry produced 59% more milk (186 billion lb. vs. 117 billion lb.) using 64% fewer cows (9.2 million vs. 25.6 million)," said Capper. She noted that this major improvement in efficiency reduced the carbon footprint per gallon of milk by 63%.
Furthermore, Capper said, the total dairy industry carbon footprint was 114 million metric tons in 2007, just 59% of the 194 million metric tons produced in 1944.
The researchers work was recently published in the Journal of Animal Science. Capper is now an assistant professor of dairy science at Washington State University.