Day-plus-night cooling strategies provide a powerful and cost-effective option against heat stress for dairy cows outdoors

Hot weather can have a big impact on dairy cattle health, well-being, and overall milk production for a herd. Dairy producers use a variety of effective cooling strategies to prevent heat stress including shade, fans, sprinklers, or a combination of all of these measures—and there is an increasing trend of having these strategies running 24 hours per day, versus only during the hottest parts of the day. 

In a recent study(opens in new tab/window) appearing in the Journal of Dairy Science(opens in new tab/window), published by Elsevier and FASS, Inc., researchers from The University of Queensland demonstrated the effectiveness of extending cooling strategies for dairy cows throughout the day and night, including how these strategies could be applied to outdoor herds with a more limited physical infrastructure.  

The study's lead investigator, John B. Gaughan, PhD, of the School of Agriculture and Food Sustainability, The University of Queensland, said, “We know logically that dairy cows should be able to dissipate body heat better at night when the ambient temperature is lower than during the day, and beef feedlot studies have suggested that nighttime heat load reduction is critical for the animals to cope with periods of heat stress. But much of the published work on cooling strategies for dairy cows has focused on cows housed in barns or feedlots, with few studies of cows that are largely pasture based or managed on a feedpad—which is a confined yarded area allowing for regular feeding of the whole herd.”

Gaughan and his team set out to fill this gap. They investigated the impacts of adding nighttime cooling in addition to daytime cooling on the milk yield, rumen temperature, and well-being of an outdoor herd exposed to high summer temperatures. They focused on 120 postpartum Holstein-Friesian cows housed on a feedpad. The herd was split into two groups of 60 cows and given two separate cooling treatments over a period of 106 days. The daytime cooling group was cooled with overhead sprinklers and fans while in the dairy holding yard, plus ducted air blowing onto cows during milking, shade and fans at the feedpad, and a shaded loafing area. The enhanced day-plus-night cooling group received the same treatment plus thorough wetting—via a shower array—as they exited the dairy, plus ducted fan-forced air blowing onto the cows at night.  

Gaughan explained, “This study is, to our knowledge, the first to investigate the potential of using ducted air as a means of cooling cows in an open pen environment overnight.”

Caption: Outdoor herds receiving an enhanced day-plus-night cooling protocol—which factored in outdoor ducted air systems (fans at the feedpad [A], and fan-forced air ducts in the shaded loafing area [B])—showed increased milk production and welfare (Credit: John Gaughan).  

The team monitored rumen temperatures using a radio-transmitting bolus at 10-minute intervals throughout the study, along with cow activity, panting score, dry matter intake, and overall milk yield. Over the duration of the study, cows in the enhanced cooling group produced more milk and had lower rumen temperatures and panting scores compared with the cows receiving just daytime cooling. Throughout the study, the enhanced cooling group cows also spent more time lying down than the daytime cooling cows.  

Gaughan said, “The combination of the shower array and the ducted air systems had a beneficial effect on milk production and cow welfare, and, critically, is a cost-effective strategy for producers to consider with outdoor herds managed on a feedpad.”

The cost of the ducted system used in the study was approximately AU$31,500 but produced AU$21,308 of additional milk income, meaning that 67.7% of the installation cost was recovered over the first summer.  

Gaughan noted, “Over time, this kind of enhanced day-plus-night cooling system could provide powerful benefits for outdoor herds, from increased production and profits to boosted cow well-being.”

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Notes for editors 

The article is “The effect of day-only versus day-plus-night cooling of dairy cows,” by John B. Gaughan, Keira L. Sharman, and Michael R. McGowan (https://doi.org/10.3168/jds.2022-22819(opens in new tab/window)). It appears in the Journal of Dairy Science, volume 106, issue 7 (July 2023), published by FASS Inc. and Elsevier. 

The article is openly available at https://www.journalofdairyscience.org/article/S0022-0302(23)00298-9/fulltext(opens in new tab/window) and the PDF version is available at https://www.journalofdairyscience.org/action/showPdf?pii=S0022-0302%2823%2900298-9(opens in new tab/window).   

Full text of this article is also available to credentialed journalists upon request; contact Eileen Leahy at +1 732 238 3628 or [email protected](opens in new tab/window). Journalists wishing to interview the authors should contact the corresponding author, John Gaughan, PhD, School of Agriculture and Food Sustainability, The University of Queensland, at [email protected](opens in new tab/window).  

About the Journal of Dairy Science 

The Journal of Dairy Science(opens in new tab/window)® (JDS), an official journal of the American Dairy Science Association®, is co-published by Elsevier and FASS Inc. for the American Dairy Science Association. It is the leading general dairy research journal in the world. JDS readers represent education, industry, and government agencies in more than 70 countries, with interests in biochemistry, breeding, economics, engineering, environment, food science, genetics, microbiology, nutrition, pathology, physiology, processing, public health, quality assurance, and sanitation. JDS has a 2022 Journal Impact Factor of 3.5 and five-year Journal Impact Factor of 4.2 according to Journal Citation Reports™ (Source: Clarivate™ 2023).

About the American Dairy Science Association (ADSA®) 

The American Dairy Science Association(opens in new tab/window) (ADSA) is an international organization of educators, scientists, and industry representatives who are committed to advancing the dairy industry and keenly aware of the vital role the dairy sciences play in fulfilling the economic, nutritive, and health requirements of the world's population. It provides leadership in scientific and technical support to sustain and grow the global dairy industry through generation, dissemination, and exchange of information and services. Together, ADSA members have discovered new methods and technologies that have revolutionized the dairy industry.

About FASS Inc. 

Since 1998, FASS(opens in new tab/window) has provided shared management services to not-for-profit scientific organizations. With combined membership rosters of more than 10,000 professionals in animal agriculture and other sciences, FASS offers clients services in accounting, membership management, convention and meeting planning, information technology, and scientific publication support. The FASS publications department provides journal management, peer-review support, copyediting, and composition for this journal; the staff includes several BELS-certified(opens in new tab/window) technical editors and experienced composition staff.

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