A pair of recent research studies has updated the environmental footprint of the dairy industry: One looks at a 50-year period in California, while the other updates previous research to account for the last decade in the U.S. dairy industry.
The first study, published in the Journal of Dairy Science, took a close look at the climate footprint of milk production in California and found that it has been significantly reduced over the past 50 years (1964 to 2014), with the amount of greenhouse gas emissions produced per unit of milk decreasing by more than 45%.
In this study, University of California-Davis (UC-Davis) researchers conducted a life-cycle environmental assessment (cradle to farm gate) of California dairy farm production using the latest scientific models and international research standards.
"The study documents the productivity, efficiency and overall sustainability of milk production in California and the critical role dairy cows play in regenerative agricultural practices and sustainable food systems," said Dr. Ermias Kebreab, UC-Davis professor and Sesnon endowed chair who led graduate student Anna Naranjo in completing the research project.
According to an announcement from the California Dairy Research Foundation (CDRF), which supported the study, key findings include:
* The amount of greenhouse gas emissions per unit of milk (e.g., glass or gallon) produced has decreased more than 45% due to increased milk production efficiency, including improved reproductive efficiency, nutrition, comfort and overall management.
* The amount of water used per unit of milk produced has decreased more than 88% primarily due to improved feed crop production and water use efficiency.
* Dramatic improvements in feed crop production and agricultural byproduct utilization have led to significant reductions in the amount of natural resources used to produce each unit of milk, including land, water, fossil fuels and energy.
"The study shows we are producing milk more efficiently and sustainably, minimizing our climate footprint in the process," CDRF chairman Richard Wagner said. "While there is always more work to be done, the findings show a significant overall improvement in environmental performance, producing more wholesome, nutritious milk and dairy products with fewer natural resources, less water, less energy and fewer fossil fuels."
The researchers expect that as milk production per cow continues to increase through improved feed formulations, reproductive efficiency and management techniques, it will lead to further improvements in the environmental footprint of dairy farming.
As the study documents, more than 40% of dairy feed ingredients in California are byproducts of other agricultural and food production processes, such as almond hulls, citrus and tomato pulp, culled carrots and other similar products that are not suitable for human consumption but make healthy, nutritious feed for cattle.
As a result, nearly half of the feed needed to produce milk in California — which represents about 20% of total U.S. milk — is being provided without a single drop of additional water, CDRF said.
While the analysis demonstrates significant reductions in greenhouse gas emission intensity (more than 45%), these estimates can be considered conservative, and more progress toward climate-smart practices continues to be made, the researchers noted.
Furthermore, CDRF said the study did not factor in the implementation of large solar panel arrays, which has occurred on more than 150 dairy farms in California and represents a significant shift toward renewable energy.
Also, the California Department of Food & Agriculture has reported that through the implementation of dairy methane reduction projects, California's dairy farms will soon be more than halfway to achieving the state's target of a 40% reduction in manure methane emissions, equating to the reduction of millions of metric tons of greenhouse gases each year.
U.S. industry, 2007-17
In 2009, Jude Capper and colleagues published a report comparing on the environmental impact of U.S. dairy production in 1944 with 2007.
In the January 2019 Journal of Animal Science, Capper, who is with the Livestock Sustainability Consultancy in the U.K., and Roger Cady, with Cady Agricultural Sustainability Specialties in Lake St. Louis, Mo., updated their previous findings for the 10 years between 2007 and 2017.
In the article, Capper and Cady noted that while milk yield per cow had increased over the decade, whole-system environmental impact analyses had not been conducted during that period, which saw considerable improvements in environmental modeling science.
Capper and Cady reported that the resources required to produce 1 mmt of energy-corrected milk in 2017 were reduced considerably relative to those required in 2007, with the industry in 2017 using "74.8% of the cattle, 82.7% of the feedstuffs, 79.2% of the land and 69.5% of the water as compared to 2007. Waste outputs were similarly reduced, with the 2017 U.S. dairy industry producing 79.4%, 82.5% and 85.7% of the manure, nitrogen and phosphorus excretion, respectively."
They also found that U.S. dairy production in 2017 emitted 80.9% of the methane and 81.5% of the nitrous oxide per 1 mmt of energy-corrected milk compared to 2007.
Capper and Cady concluded that the U.S. dairy industry has made "remarkable productivity gains and environmental progress over time" and that the industry must build on those gains and demonstrate its "commitment to reducing environmental impacts while improving both economic viability and social acceptability."