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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Publications at this Location » Publication #403106

Research Project: Sustainable Forage Production Systems for the Mid-South Transition Zone

Location: Forage-animal Production Research

Title: Lamb feed supplementation with natural red clover product biochanin A reduces soil trace gas emissions of nitrous oxide and methane and volatilization of ammonia in urine excreta patches

Author
item JACOBS, ALAYNA - Oak Ridge Institute For Science And Education (ORISE)
item Flythe, Michael
item ELY, DON - University Of Kentucky
item MUNOZ, LEAH - University Of Kentucky
item MAY, JOHN - University Of Kentucky
item NELSON, JIM - University Of Kentucky
item STANTON, VICTORIA - University Of Kentucky
item PHAM, KENT - University Of Kentucky
item MCCULLEY, REBECCA - University Of Kentucky

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sustainable growth in ruminant livestock production requires increases in animal production efficiency and reductions in livestock-induced greenhouse gas emissions on grazing lands. Urine excreta patches are hotspots for accelerated emissions of carbon and nitrogen-based trace gases. Ruminant feed supplementation with the isoflavone biochanin A (BCA), a plant secondary metabolite naturally produced by red clover (Trifolium pratense L.), has been shown to improve cattle weight gain performance by enhancing protein digestibility. The objective of this study was to determine whether BCA feed supplementation affected urinary N excretion amounts and soil trace gas emissions by amending soil with urine from lambs in a laboratory incubation study. Results showed that feeding lambs BCA reduced daily soil urine patch emissions by 78% for nitrous oxide and 5% for methane compared to urine from non-dosed lambs, and cumulative ammonia volatilization by 35%. However, BCA dosing did not affect overall urinary nitrogen content or structures of the soil microbial communities. Results were confirmed in a separate incubation when BCA was added directly to urine and added to soil. In summary, results of this study show livestock BCA supplementation may mitigate greenhouse gas emissions in the livestock industry and support sustainable production goals.

Technical Abstract: Sustainable growth in ruminant livestock production requires increases in animal production efficiency and reductions in livestock-induced greenhouse gas emissions on grazing lands. Urine excreta patches are hotspots for accelerated emissions of carbon and nitrogen-based trace gases. Ruminant feed supplementation with the isoflavone biochanin A (BCA), a plant secondary metabolite naturally produced by red clover (Trifolium pratense L.), has been shown to improve cattle weight gain performance by enhancing protein digestibility. To determine if BCA supplementation affects urinary N excretion amounts and soil trace gas emissions, soil in laboratory microcosms were amended with urine from nine lambs fed no BCA and fed BCA at two levels: 0.45 and 0.90 g BCA day-1. Feeding lambs BCA reduced daily emissions of nitrous oxide by 78% (p <0.0001), methane by 5% (p = 0.0470) compared to urine from non-dosed lambs on days when gas concentrations differed significantly. Cumulative ammonia volatilization was reduced by 35% (p = 0.0132) compared to non-dosed lambs, though urinary N content was unaffected by BCA dosing (p = 0.842). A separate incubation using urine from a lamb fed no BCA but spiked exogenously with varying BCA levels confirmed these results, as BCA significantly decreased daily emissions of methane (p = 0.0036) and ammonia (p < 0.0001) and cumulative ammonia and nitrous oxide emissions (p <0.0001 and 0.0004, respectively). In both incubations, BCA dosing did not change soil microbial community structure, indicating that BCA altered other processes in urine patches such as soil enzyme activity that led to reductions in soil trace gas emissions. Overall, results of this study show livestock BCA supplementation may mitigate greenhouse gas emissions in the livestock industry and support sustainable production goals.