UC Davis

The growing demand for high quality food resulting from the increase in world population has incentivized the agriculture industry to increase their food production. However, large amounts of biomass and byproducts from food production are sent to landfills. Many of these wastes, despite no longer being suitable for human consumption, are often still rich in nutrients and represent valuable alternatives to complement animal feed. Livestock, especially ruminants, are an integral part in agriculture as they can convert plant biomass that cannot be digested by humans into high quality animal products such meat, milk and wool. The ability of ruminant animals to degrade recalcitrant plant fibers is due to the symbiotic relationship with the microorganisms that reside in the rumen and that can digest and convert plant biomass into nutrients and metabolic intermediates that can be further utilized by the host animals. Some of these microorganisms produce greenhouse gases, such as methane (CH4), which is released into the atmosphere where it has detrimental effects on the environment. Many byproducts from agriculture may contain bioactive compounds such as phenolics, organosulfur, terpenoids, and fatty acids that can alter rumen fermentation and even inhibit methanogenesis. California is the largest producer of agricultural products in the United States (U.S.), with a large arsenal of byproducts that could hold the key to improve ruminant nutrition and also have the potential to reduce enteric methane production. As of today, there is still only a limited number of studies that have investigated the potential of California byproducts to reduce enteric fermentation. In the work presented here, a panel of byproducts from California agriculture was subjected to chemical profiling and subsequent in vitro rumen fermentation. In addition to providing first insights into the potential effect of the tested local byproducts this work also provides a framework and the standard operating procedures that should be employed for future analyses to identify potential methane inhibitor and to enable comparisons of results that will be generated over time and from different researchers and institutes. A standardization of the analytical methods to evaluate rumen response will be key to not only identify novel strategies but also provide the framework to study the molecular drivers of methane inhibition and to optimize future methane mitigation strategies.