How much does heat stress really cost? What’s the difference among sprinklers, misters and soakers? Which barn design will optimize ventilation efficiency?
If the thought of heat stress is making you hot under the collar, it’s time to chill out – because there is finally one place to find the answers to your common questions on dairy cow cooling.
The University of Wisconsin – Madison has published a paper summarizing key studies on the effects and economics of heat stress, along with abatement systems and strategies.
“Dairy Cooling: The Benefits and Strategies” is the work of doctorate student Ian Atkins under the direction of professors Chris Choi and Brian Holmes in the department of biological systems engineering.
Click here or on the image above to view it at full size in a new window. (PDF, 962 KB)
“The article does not provide new information,” Atkins explains. “The goal is, rather, to put existing information on heat stress, cooling equipment and economics into a single summary and make it available for free.”
With the financial support of Schaefer Ventilation of Sauk Rapids, Minnesota, and assistance from their experienced industry professionals, Atkins was able to collaborate this valuable data.
It is categorized in an easy-to-reference format based on the following categories: heat stress, heat abatement strategies, facility and ventilation design, milking center ventilation and cooling, economics of cow cooling, and research and emerging technologies.
Atkins’ broader vision is that dairies will not only improve heat abatement but also the efficiency of the task.
“I hope this information will help dairy producers select and operate equipment that effectively mitigates heat stress at the least cost while using as little water and electricity as possible,” he says.
Tailor a cooling solution to your climate
From the hot and sticky southern states to the bone-dry regions of the West, there is no one-size-fits-all solution for dairy cooling. From coast to coast, temperature and humidity vary greatly.
That’s why Atkins has also compiled the companion climate-specific guides, a separate set of resources intended to describe best practices for choosing adequate systems and optimizing their functionality for a particular herd in that climate.
The guides are as follows: “Dairy Cooling in Arid and Semi-Arid Climates,” “Dairy Cooling in Humid Continental Climates” and “Dairy Cooling in Humid Subtropical Climates.”
Watch upcoming issues of Progressive Dairyman for the climate-specific guides.
To better understand the costs associated with heat stress and how to alleviate it, view the full white paper, “Dairy Cooling: The Benefits and Strategies.”
The future of dairy cooling: Digital cows
A University of Wisconsin professor is using virtual technology to design better ventilation systems for dairy facilities. UW’s Chris Choi explains how he uses a herd of computer-simulated cows to determine the best systems for real-life barns.
How do you use computer simulation and ‘digital cows’ to study and design air flow in dairy buildings?
CHOI: The computational models we use can estimate air flows, heat removal rates and concentrations of ammonia and methane. They can also analyze the air-flow patterns that form inside a dairy barn as well as temperature gradients and animal responses in newly designed facilities. Being able to quantify these variables greatly facilitates the design process and the testing of hypotheses.
Using the digital cow model (Figure 1), for example, we were able to create a virtual holding pen occupied by virtual cows and use it to accurately assess the heat removal rate occurring in a particular target zone at different wind speeds (Figure 2).
The virtual animals in the model can be crowded at various densities to simulate the often densely packed herds of real cows waiting to be let into the milking parlor. In such instances, the increase in thermal mass within a space that is inadequately ventilated can bring on the problems commonly associated with heat stress.
Likewise, through a series of ongoing studies, our team has been developing computer models that can reduce the computation time and outcome-validating process associated with field experiments designed to reduce heat stress.
What are the advantages of using digital cows to design dairy buildings?
CHOI: These computer-generated models are far more manageable than real cows, and their mathematically simplified contours (which have been verified using real cows) can be used to analyze the ways in which air flow can be disrupted by real animals and how a given density of animals can affect heat transfer and reduce a particular ventilation system’s efficiency.
The cow models can also be integrated with computer-generated dairy buildings in order to test the building’s design parameters, of which there are many (for example, the number of fans and animals and their spacing, the wind speed, temperature, air exchange rate, ceiling height, location of baffles, etc.).
Once the digital cows have been added to a model, each of its design parameters can be analyzed under different animal densities, the climate inside the barn more accurately simulated and a wider range of climate data compiled in far less time (and at a lower cost) than would be required to handle such complex geometries using traditional methods.
How will computer simulation change the way we cool cows in the future?
CHOI: Eventually, simulation packages equipped with user-friendly interfaces should be available (via the Internet) to dairy housing designers and dairy producers so they can analyze and optimize their own specific dairy barns and ventilating systems. PD
Computational work was conducted by Mario Mondaca under the supervision of professor Choi.
