2024 September Board Book

GRAPE POMACE MIXED IN FEED CAN REDUCE DAIRY CATTLE EMISSIONS

Researcher: Dr. Ermias Kebreab, UC Davis

TWO OF THE LARGEST COMMODITIES IN CALIFORNIA CAN WORK TOGETHER TO REDUCE WASTE AND METHANE EMISSIONS. ADDING FRESH GRAPE POMACE TO FEED CAN REDUCE ENTERIC METHANE EMISSIONS WITHOUT IMPACTING MILK YIELD OR COMPOSITION.

California leads the nation in wine and milk production. These agricultural industries contribute billions of dollars to California’s economy and create thousands of jobs, but they also are responsible for contributing to greenhouse gas emissions. California’s wineries and dairies are each looking for ways to significantly reduce their carbon footprint. A new study from UC Davis suggests a synergistic solution. Adding grape pomace—the skins, pulp, seeds, and stems leftover after pressing grapes for wine—to cattle feed could reduce methane emissions from dairy cows while reducing waste from wineries. In addition to these environmental benefits, grape pomace has the potential to improve the quality of dairy cattle feed and reduce the cost of feed production. There is one potential catch, however. Previous studies have found that adding grape pomace to cattle feed reduced milk yield. Dr. Ermias Kebreab, UC Davis Department of Animal Science, investigated the effect of replacing a portion of the dry matter from alfalfa feed with fresh grape pomace on dairy cow milk and methane production. His goal was to identify the optimal amount of grape pomace that could be substituted into the dairy cow’s normal diet while maintaining milk production and milk quality. Grape pomace contains chemicals called polyphenols that have anti-methanogenic and immune-modulatory

effects. When consumed by dairy cattle, polyphenols, particularly condensed tannins, have shown the ability to act like a prebiotic and promote the growth of beneficial bacteria such as Lactobacillus and Bifidobacterium . These beneficial bacteria produce short chain fatty acids rather than producing methane as a byproduct of fermentation. Dairy cows were rotated through three formulated diets to determine the most effective formulation of grape pomace Twenty-four Holstein dairy cows were first fed a control ration for two weeks and then each cow was randomly assigned to one of three treatment groups: control diet (CON), diet with 10% grape pomace on a dry matter basis (10% GP), and a diet with 15% grape pomace on a dry matter basis (15% GP). Cows were in each treatment group for four weeks. Milk production and methane emissions were measured daily, and milk composition was measured weekly. The study included fresh grape pomace, which was deliv ered twice a week from California wineries and manually added to feed. Fresh grape pomace has the disadvantage of a shorter shelf life than processed grape pomace. However, ensiled or dried grape pomace has previously been shown to compromise anti-methanogenic and immune effects by altering the biological properties of tannins. Moreover, processing grape pomace for ensiling and drying can add additional costs. The study found that adding fresh grape pomace to dairy cattle feed can be an effective means of reducing enteric

14

Made with FlippingBook Digital Publishing Software