ABSTRACTRESOURCE USE AND CONSERVATION AND ENVIRONMENTAL IMPACTS IN THE TRANSITION FROM CONFINEMENT TO PASTURE-BASED DAIRIESByM. Melissa Rojas-DowningIn recent years, many farms have transitioned from total confinement housing to a pasture-based system in an effort to reduce labor and production costs and improve profitability. There is a growing interest in biogas recovery among livestock producers to reduce energy costs and manure odors but the economic benefits of anaerobic digestion (AD) on small farms is not well known. A comprehensive analysis was conducted using the Integrated Farm System Model, to describe, evaluate and compare the economics, farm performance and environmental impacts of representative dairy farms in Michigan transitioning from conventional confinement to a seasonal- and pasture-based systems, and evaluate the potential for integration of an AD in the confinement and seasonal pasture systems. In the economic analysis the annual pasture-based system had the greatest net return to management and unpaid factors followed by the seasonal pasture and confinement systems. The addition of an AD on a 100-cow, total confinement dairy decreased the net return to management and unpaid factors by 15%. Cycling manure nutrients led to an annual depletion of soil P and K on the confinement dairy and a build-up of P and K on the seasonal- and pasture-based dairies. There was little change in N, P and K or carbon loss to the environment due to AD. In the seasonal and annual pasture-based systems, ammonia emissions increased by more than 100%. The water and reactive nitrogen footprint increased and energy footprint decreased compared to the confinement dairy.
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