Simple Summary
Beef cattle production is vital to Montana’s Economy, but the ruminal fermentation of cattle produces methane, a potent greenhouse gas that represents a loss of dietary energy. Simultaneously, invasive weeds threaten local pastures, displacing native plants. This study aimed to evaluate seven invasive weeds from South-Central Montana to assess whether the plants or their chemical components could be used as feed additives to reduce methane emissions. Using laboratory simulations of cattle digestion, we discovered that Common burdock and Curly dock altered fermentation, reducing methane production. Likewise, extracts from common burdock achieved a 25% reduction in methane production without affecting the digestion of the diet. Although Curly Dock reduced methane volume, it drastically reduced overall feed digestibility. We concluded that certain invasive weeds can be upcycled as a local feed additive to reduce greenhouse gases from livestock production. These findings may benefit society by offering ranchers a cost-effective strategy to improve cattle efficiency while creating an innovative use of invasive weeds, fostering environmental sustainability.
Abstract
(1) Background: Beef cattle production is essential for Montana’s economy. These operations rely on fibrous diets promoting enteric methane (CH4) emissions, resulting in dietary energy inefficiency and environmental impacts. Concurrently, noxious weeds invade approximately 10% of state rangeland. Yet, some species produce plant secondary metabolites (PSMs) that could be repurposed for CH4 mitigation strategies. (2) Methods: This study evaluated seven invasive weeds from South-Central Montana using in vitro incubations with ruminal fluid from cannulated Angus Cows (590 ± 18 kg). Experiment 1 screened whole plants added at 20% of incubated dry matter (IDM) against a control (hay), then, experiment 2 evaluated ethanolic extracts from leaves and inflorescences from top candidates identified in experiment 1. (3) Results: In the screening phase, common burdock (BURD) and Curly dock (DOCK) modified fermentation dynamics. BURD leaf extract achieved a 25.2% reduction in CH4 yield (mL/g fermented organic matter) without compromising in vitro organic matter digestibility (IVOMD) or ammonia (NH3-N). Conversely, DOCK extracts demonstrated the strongest CH4 volume reduction but at the cost of a dramatic reduction in IVOMD and NH3-N depletion. Bioactivity of PSM remained consistent across anatomical structures. (4) Conclusions: Specific weeds (BURD, DOCK) represent a biochemical repository with potential as a feed additive for roughage-based diets. Leaves from BURD exhibited optimal potential to mitigate CH4 emission without impairing diet digestibility.