ENVIRONMENTAL MONITORING AND MANAGEMENT IN DAIRY SYSTEMS: AIR QUALITY DYNAMICS, CALF BEDDING MICROBIOME, AND PRECISION TECHNOLOGIES FOR SUSTAINABLE PRODUCTION

Abstract

ENVIRONMENTAL MONITORING AND MANAGEMENT IN DAIRY SYSTEMS: AIR QUALITY DYNAMICS, CALF BEDDING MICROBIOME, AND PRECISION TECHNOLOGIES FOR SUSTAINABLE PRODUCTION Modern dairy production systems have undergone substantial intensification to improve productivity, efficiency, and economic viability. This transformation has created complex housing environments where animals, workers, manure, bedding materials, ventilation systems, and management activities continuously interact. These interactions influence indoor air quality, thermal conditions, microbial exposure, animal comfort, worker safety, and environmental sustainability. Understanding these environmental conditions is increasingly important because dairy systems emit multiple air pollutants, including methane, carbon dioxide, ammonia, particulate matter, volatile organic compounds, and bioaerosols, each with potential implications for animal health, occupational exposure, and environmental impact. In addition, young calves are exposed to distinct microenvironments within individual housing systems, where bedding conditions and microbial load may influence disease risk, welfare, and growth. Therefore, this dissertation evaluates environmental quality in dairy systems by integrating air quality monitoring, spatial pollutant assessment, calf bedding sanitation, microbial exposure, and precision dairy technologies.Chapter 1 provides a literature review of dairy intensification, indoor air quality, thermal stress, greenhouse gases, airborne pollutants, ventilation systems, calf housing microenvironments, bedding microbiomes, and precision dairy technologies. This chapter establishes the scientific foundation for the dissertation by showing that dairy environmental conditions are shaped by interacting biological, physical, microbial, and management factors. It also identifies key knowledge gaps related to spatial and temporal air quality dynamics, pollutant behavior across ventilation systems, bedding-associated microbial exposure in calf hutches, and the role of precision technologies in supporting sustainable dairy management. Chapter 2 of this dissertation characterizes the dynamics of air quality in a tunnel-ventilated dairy barn and rotary milking parlor. This chapter described the temporal dynamics of key air components, including greenhouse gases, ammonia, particulate matter, volatile organic compounds, and thermal indicators. By evaluating air quality in relation to housing area and environmental conditions, this work provides insight into how pollutants accumulate, disperse, and vary in a mechanically ventilated dairy environment. The findings highlight the importance of continuous monitoring for identifying pollutant dynamics that may not be captured through short-term or single-point measurements. The third chapter examines spatial volatile organic compound concentrations in natural and mechanically ventilated dairy farms. Volatile organic compounds are important dairy-related air pollutants because they are emitted from feed, silage, manure, bedding materials, and microbial decomposition processes and can contribute to odor, ozone, and particulate matter formation, as well as indoor air quality concerns. This chapter evaluated how VOC concentrations varied across different dairy systems and within barn locations, emphasizing the role of housing design, ventilation, airflow, and management activities in shaping spatial pollutant patterns. This work contributes to a better understanding of VOC distribution in dairy environments and supports the need for multi-location monitoring to identify potential pollutant hotspots. Chapter 4 focuses on the calf housing microenvironment by evaluating the impact of bedding sanitation practices on bacterial load and the microenvironment of individual calf hutches. Bedding is a major component of the calf microenvironment because it influences comfort, insulation, moisture retention, ammonia generation, microbial proliferation, and pathogen exposure. Wet or contaminated bedding can support bacterial growth and may increase exposure to organisms associated with diarrhea, respiratory disease, and other calf health challenges. This chapter assesses whether bedding sanitation practices could reduce bacterial load and improve the microbial quality of the calf housing environment. By connecting bedding management, microbial exposure, and microenvironment, this work addresses an important knowledge gap in calf-hutch environmental management. The final chapter systematically reviewed precision technologies used in the United States dairy farming, with emphasis on applications in animal health, behavior, reproduction, and environmental management. Precision technologies, including wearable sensors, rumination monitors, milk monitoring systems, imaging tools, environmental sensors, and decision-support platforms, provide continuous and real-time data that can support earlier disease detection, reproductive management, welfare assessment, and environmental control. This review placed the findings from the previous chapters within a broader framework of data-driven dairy management and highlighted available precision technologies in the United States, which may be a potential tool for producers and farmers to improve resource-use efficiency, farm profitability, animal welfare, worker safety, and environmental performance. Overall, this dissertation demonstrates that sustainable dairy production requires an integrated understanding of air quality, housing design, ventilation, microbial exposure, calf microenvironment, and digital monitoring technologies. The findings emphasize that dairy environmental conditions are spatially and temporally dynamic and that continuous, multi-location, and data-driven monitoring is necessary to support effective management. By linking barn-level air quality, VOC distribution, calf bedding sanitation, and precision technologies, this dissertation contributes to the development of more sustainable dairy production systems.