Dairies Upcycle California Farm By-Products to Improve Sustainability

Cows at the UC Dairy.
Photo credit: Karin Higgins/UC Davis

From almond hulls to winegrape pomace, use of agricultural by-products in California dairy rations helps keep dairies and crops financially viable while reducing waste and water use.

Recent findings by researchers from UC Davis and UC Cooperative Extension published in the Nov/Dec 2020 edition of ARE Update detail the use of local agricultural by-products by California dairies for feed rations and examines their economic and environmental impacts. The research explored the symbiotic relationship between California dairies and local crop producers that substantially reduces the waste from both industries and saves land and water resources for food production.

Dairy production is California’s largest farm commodity by revenue, generating around $7 billion in value. Dairy feed rations represent more than half of the cost of milk. California has approximately 1.7 million dairy cows, the highest number in the United States. 90% of those cows are located in the Central Valley. These dairies are surrounded by millions of acres of nuts, fruits, vegetables, and cotton, which are frequently processed locally. By-products from the production of these crops are then used, with minimal processing and transportation costs, to feed dairy cows.

The authors’ 2019 survey of California dairies showed that 95% of survey respondents used these by-products in feed and more than 70 distinct by-products, most of which are produced in California, may be used in dairy rations. California dairies feed cows a huge range of products, including items like carrots and brewers’ spent grains. On average, by-products account for 35% of feed costs and 35% of the dry matter fed to California dairy cows and heifers. In terms of dry matter, almond hulls, canola meal, cottonseed, and distillers’ grains were the major by-product feeds used by California dairies.

If by-products were not available, the authors estimate a 20% increase in the cost of feed rations, which means a 10% increase in milk production costs. About 95% of the 2.55 million tons of almond hulls are used as dairy feed, and if they were not available, milk production would fall by about 2%. Other crops such as cotton, with 20% of its revenue generated through sales of cottonseed for dairy feed, would suffer if dairies were not able to buy these by-products.

Benefits of the close relationship between dairies, crop industries and processors are not only economic. For many crops, other uses of by-products require additional processing and transportation, increasing the cost, resource use, and carbon footprint. By-products without alternative uses would be wasted and could end up in landfills, adding to methane emissions. And, if dairies could not access local by-products, more-scarce farmland and irrigation water would be needed for production of silage and alfalfa, leading to a further strain on these already limited resources. Overall, the authors show that the use of by-products in dairy rations benefits both agriculture and the environment, improving the sustainability of California agriculture.

To learn more about the use of agricultural by-products in dairy rations and their effects on sustainability, read the full article at https://giannini.ucop.edu/filer/file/1607719951/19917/


ARE Update is a bimonthly magazine published by the Giannini Foundation of Agricultural Economics to educate policymakers and agribusiness professionals about new research or analysis of important topics in agricultural and resource economics. Articles are written by Giannini Foundation members, including University of California faculty and Cooperative Extension specialists in agricultural and resource economics, and university graduate students. Learn more about the Giannini Foundation and its publications at https://giannini.ucop.edu/.

Media contacts:

Ria DeBiase, Communications Editor, Giannini Foundation for Agricultural Economics, 530- 752-3508, rwdebiase@ucdavis.edu  

Daniel A. Sumner, Distinguished Professor, Department of Agriculture and Resource Economics, UC Davis, dasumner@ucdavis.edu  

Richard J. Sexton, Distinguished Professor, Department of Agriculture and Resource Economics, UC Davis and Editor, ARE Update, Giannini Foundation of Agricultural Economics, rjsexton@ucdavis.edu