Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218
Performing Department
Biological Systems Engineering
Non Technical Summary
The specific aim of this multidisciplinary, multistate, and integrated project is to promote more economically and sustainable dairy farm production systems. Heat stress of dairy cows is an ever-increasing menace to dairy production because of global warming and the increasing internal heat production of high yielding cow. Heat stressed cows produce less milk, and they are susceptible to diseases, and have impaired fertility, all of which have a large economic toll. Dairy producers need desperately heat abatement technologies and management strategies that are economically feasible. It is not known what the optimal ventilation technologies and management strategies are for specific types of dairy farms. Farmers are making multi-million dollar investments on heat abatement technologies without knowing their effectiveness. It is imperative to provide science-based information to assist dairy farmers in making the best decisions that optimize cow comfort at the least cost investment. We propose to help in this area by studying the most promising cooling technologies on modern commercial dairy farms by using state-of-the-art fluid dynamics knowledge together with innovative measurements, which will be related to cow behavior and performance, and then incorporated into a dynamic, interactive economic model that can predict the best economic outcomes according to farm specific conditions. Our ultimate goal, beyond the time-scope of the specific project, is to develop a decision support system tool that aids farmers in the decision-making of investment in cooling abatement technologies.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Analyze whole farm system components and integrate information into decision-support tools to improve efficiency, enhance profitability, and environmental sustainability.
Project Methods
With little consensus among designers currently working in the industry, the primary objective of this proposal is to evaluate the state of the heat abatement technology in its current form in the Wisconsin dairy industry and to do so by bringing to bear expertise in the fields of CFD, cow behavior and economic modeling. The use of modeling will save producers and builders from repeating design mistakes as it will allow us to ask questions that would be difficult or impossible to answer if an actual facility had to be built to answer them.Our long-term goal is to establish a design standard for large-scale barns and provide customizable decision support tools for improved economic decision-making. Our approach will include the following specific steps: (i) work with current building designers to identify current design trends in an effort to develop optimally designed mechanically ventilated and hybrid (mechanically and naturally ventilated) barns, (ii) visit typical mechanically ventilated barns to perform animal and ventilation measurements in order to determine those design characteristics that are preferred by cows and those which are not, (ii) create a design platform to facilitate CFD models, one based on design trends and actual observations, (iv) determine the actual costs associated with the construction, maintenance and running a ventilation system that can create optimal ventilation models at the least cost, and (v) conduct a comprehensive economic analysis.Specific goals: The specific goals are to prioritize 4 design traits for mechanical ventilation systems.A way to provide fast moving air in the cow's resting space (>7 km/hr or 4.5 mph).A system that works optimally across all 4 seasons - providing adequate air changes per hour during the winter to prevent pneumonia and sufficient cooling in the summer to prevent heat stress.A flexible design (hybrid) to allow for switching between natural and mechanical ventilation between seasons.An analysis of the economic factors important to the design and maintenance of the system to provide optimal performance at least cost according to farm specific conditions. Therefore, the proposed tasks are to (i) develop a dynamic, cow-level, stochastic, dairy herd simulation model capable of quantifying the economic, environmental, and health impacts of various housing facilities, heat abatement technologies and management strategies, and (ii) achieve the extension goal, supported by developed modelling, using lessons learned during the project's CFD research phase and via our connection with the dairy industry and dairy producers; that is, we intend to disseminate all project findings and promote housing facilities and management strategies that can achieve better farm-specific heat abatement.Significant questions, yet to be answered, have arisen regarding actual airflow patterns, temperature gradients and cow environmental preferences within mechanically ventilated barns. In addition, CFD work requires boundary conditions, and the outcomes of the computational simulations must be validated in comparison with the experimentally measured data. Therefore, we propose to study 2 mechanically ventilated cow barns in order to evaluate cow behavior and inform our models using real time data collected from barns that are currently operational. We will choose one barn laid out in typical cross-vent design and one in typical tunnel-vent design. The herds will be selected based on referrals to the Dairyland Initiative program.Based on the 3D model facilities created, a series of virtual dairy facilities will be built for computational simulations. These facilities should consist of walls with measured seasonal boundary conditions. The CFD model's boundary conditions included walls with appropriate emissivity and the inlet and outlet air speed, temperature, evaporative cooling, and relative humidity conditions. Both radiation and convection within the animals' hair layer will be developed in the animal occupied zone (AOZ) model, and evaporation and sweating may also be considered. The airflow will be considered turbulent, and the flow patterns will be found by using the realizable k-ε turbulence model.We propose to assess and evaluate every economic factor associated with the design, construction and operation of a modern dairy housing and cooling system. We will also project these economic factors across time and with respect to the uncertain conditions of weather, prices, and, importantly, the impacts that the studied cooling systems may have on such dairy-farm performances as animal productivity and well-being. Cabrera's team will first develop a next-event daily dynamic stochastic Monte Carlo simulation model of a dairy herd's dynamics (cow-flow, herd structure) with emphasis on cow-specific heat impacts. The model will be capable of using actual cow-level characteristics and follow each individual cow (and her possible replacements), through all possible stochastic events for a determined period of time (e.g., five years) to assess the economic, environmental (i.e., water and energy usage), and health impacts of various heat abatement management strategies.Specifically, individual cows will be simulated as if living through stochastic events within reproductive cycles. A dataset of cows in a herd and their current characteristics (i.e., lactation number, number of days postpartum, reproductive status, milk production, etc.) will be loaded from actual farm records. Then, for each cow, possible events in the future will be stochastically scheduled. All of these factors will affect and be affected by the conditions of heat stress that will be communicated by the CFD model.The focus will be on the heat stress exposure, tolerance, and impact and its alleviation that can be achieved by abatement technologies and management strategies. The spatial-temporal stochastic component will be a novel component for this livestock model. In addition to simulating the bio-physiological stochastic characteristics of a cow existing in a determined time period, it will be important to simulate, stochastically, the location and corporal position of the cow within the facilities. We have evidence indicating that the cooling abatement is greatly variable within a facility according to the technology used, and, therefore, the heat stress impact on a particular cow will depend, among other factors, on her location and corporal position. Also, the heat stress a cow suffers can have both immediate impacts (e.g., decrease in productivity) and more long-term effects (e.g., delayed calving interval); consequently, the model must identify each cow and follow her through successive lactations according to the cow exposure and tolerance to heat stress.The goal of the economic model is to inform dairy farm managers of the investment-benefit of heat abatement technologies and strategies according to farm specific conditions. The model will be developed to receive farm and cow specific information (e.g., herd reproductive performance or cow genetic potential) and based on these project the farm specific impact of different heat stress scenarios. The economic model will be used to perform virtual applied research on which heat stress abatement management technologies are more promising. Ultimately, the economic model will become the core baseline of future development of a decision support tool for use and application in dairy farms.