Dairies upcycle California farm by-products

UC Davis

Use of ag by-products in California dairy rations reduces waste and water use

Recent findings by researchers from UC Davis and UC Cooperative Extension that are published in the Nov/Dec 2020 edition of ARE Update, details 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 around 1.7 million dairy cows, the highest number in the United States, and 90% of those are in the Central Valley. These dairies are surrounded by millions of acres of nuts, fruits, vegetables, and cotton that 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 the survey respondents used these by-products in feed and that more than 70 distinct by-products, most of which are produced in California, may be used in dairy rations. California dairies feed a huge range of products, including such disparate products as carrots and brewers’ spent grains. On average, by-products account for 35% of the feed costs and 35% of the dry matter fed to California dairy cows and heifers. On a dry matter basis, 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 requires 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 how the use agricultural by-products in dairy rations and its effects on sustainability, read the full article by Scott Somerville (Ph.D. student, UC Davis), Daniel A. Sumner (Distinguished Professor, Dept. of Agricultural and Resource Economics, UC Davis; and director of the UC Agricultural Issues Center), James Fadel (Professor, Dept. of Animal Science, UC Davis), Ziyang Fu (former undergraduate student, UC Davis), Jarrett D. Hart (postdoctoral scholar, UC Davis), and Jennifer Heguy (UC Cooperative Extension Farm Advisor): “By-Product Use in California Dairy Feed Has Vital Sustainability Implications” ARE Update 24(2): 5–8. UC Giannini Foundation of Agricultural Economics online at https://giannini.ucop.edu/publications/are-update/.

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/.

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