Awards issued prior to january 20, 2025, were funded under previous administrations and may not reflect the priorities and policies of the current administration.** the pressure to reduce GHG…

Awards issued prior to january 20, 2025, were funded under previous administrations and may not reflect the priorities and policies of the current administration.** the pressure to reduce GHG emissions from dairy farming systems is growing in the US. The US dairy net zero initiative is a program seeking the reduction of the environmental footprint of dairy farming systems through the reduction of enteric methane emissions from dairy cattle. Therefore, IT is critical that researchers find novel nutritional strategies to reduce enteric methane emissions from dairy farming systems. Our working hypotheses are that alfalfa yields can increase in the climate change scenario through renovated variety selection and harvest regime and that feeding high-quality alfalfa to dairy cattle can reduce methane emissions through a better synchrony between the rates of ruminal fiber digestion and ruminal fiber passage. We will conduct agronomic field research experiments evaluating the impact of variety selection and harvest regime on alfalfa forage yield and quality under climate change conditions in pennsylvania and virginia. These agronomic experiments will provide forage samples to evaluate neutral detergent fiber (NDF) ruminal digestion kinetics. We will also conduct animal feeding trials evaluating how the forage passage rate affects enteric methane emissions from dairy cattle when feeding diets containing alfalfa as forage sources. In addition, we will conduct a comprehensive literature review and a life cycle analysis (LCA) to quantify the carbon footprint of dairy systems incorporating alfalfa relative to dairy systems based exclusively on annual crops (corn silage and cool-season cereal grasses). We will conclude this project by transferring knowledge to dairy nutritionists through a holistic extension program. As an outcome of this project, we foresee dairy nutritionists recommending seeding more alfalfa in the US in response to the global demand for a dairy industry moving towards zero net GHG emissions.