Innovative cooling strategies: Dairy cow responses and water and energy use

Abstract

Producers in the western United States commonly use spray water at the feed bunk and fans in the lying area to mitigate heat stress in dairy cows. Often, spray water cycles on and off with fans turning on when a preset air temperature is reached. Although this method can be effective, innovative strategies are needed to reduce water and energy use. We evaluated the effectiveness and resource efficiency of 4 cooling treatments on behavioral and physiological responses in dairy cows housed in a freestall barn: (1) conductive cooling in which mats with recirculating evaporatively cooled water were buried under sand bedding (Mat; activated at 18.9°C); (2) targeted convective cooling in which evaporatively cooled air was directed toward the cows through fabric ducts with nozzles at both the feed bunk and lying areas (Targeted Air; activated at 22°C); (3) evaporative cooling, with spray water in the feed area and fan over the freestalls (Baseline; activated at 22°C); and (4) evaporative cooling with half the amount of spray water used in the Baseline and the fan moved to the feed bunk (Optimized Baseline; activated at 22°C). In a crossover design, 8 groups of cows (4/ group) producing an average (± standard deviation) of 37.5 ± 4.5 kg/d of milk were tested for 3 d per treatment. For ethical reasons, beginning at 30°C, the Mat treatment was supplemented with Baseline cooling and the Targeted Air treatment had spray water at the Optimized Baseline rate. We recorded body temperature, posture, and location within the pen every 3 min for 24 h/d, and respiration rates every 30 min daily from 1000 to 1900 h. Daily air temperature averaged (±SD) 26.3 ± 7.1°C during 24 h and 33.3 ± 4°C from 1000 to 1900 h. We used pairwise comparisons of each treat-ment to Baseline to evaluate response variables. Milk production did not differ across treatments, nor did time spent lying (51 ± 2%/d on average). Respiration rates did not differ across treatments overall (61 ± 3 breaths/min), but on an hourly basis, cows in the Mat treatment had a significantly higher rate than those in Baseline, at h 10 and 11 (70 vs. 58-59 breaths/min). Body temperature averaged 38.7 ± 0.05°C across treatments and was 0.2 to 0.3°C higher in the Mat treatment than in Baseline at h 10, 11, 20, 21, and 22. These results collectively indicate that the Mat treatment did not effectively reduce indicators of heat load compared with Baseline. In contrast, Targeted Air and Optimized Baseline were both effective but differed in aspects of efficiency. Targeted Air used the least amount of water but the most energy of all options tested. In conclusion, more efficient heat abatement options were identified, particularly an Optimized Baseline strategy, which cut water use in half, required the same amount of energy as the Baseline, and maintained similar physiological and behavioral responses in cows.

Thermoregulation and Performance of Dairy Cows Subjected to Different Evaporative Cooling Regimens, with or without Pepper Extract Supplementation

“…The use of 2 evaporative cooling regimens was chosen, aiming for a 50% reduction in water volume from 10 to 5 min (R10 to R5). The sprinkler and ventilation systems were continuously automated, and the system was activated whenever the temperature exceeded 22.2 °C, as previously described by [ 15 ]. Under thermal conditions above 22.2 °C, the sprinkler system was intermittent (30 s on and 4.5 min off [R5] or 30 s on and 9.5 min off [R10]); however, ventilation was constant, regardless of the air temperature.…”

“…The presence of an animal in the feeding track was recorded every time within a period of 48 h, with the recording of the start and end times, which allowed obtaining the number of visits, partial time, and total time that the animals were exposed to the climate control system [ 15 , 27 ]. Specifically, the estimated number of visits to the feeding track was based on the presence of the animal in the track for more than 30 s, i.e., the spraying time of each cycle, which was also 30 s.…”

“…Studies using this type of cooling, called direct cooling, have reported lower surface and rectal temperatures [ 11 , 12 ], an 8% reduction in respiratory rate, and an increase in milk production of approximately 8.6% [ 13 , 14 ]. However, the use of water resources in animal production has been a point of environmental concern, requiring efficient management of such resources [ 15 ]. In light of the positive impact on animal welfare, the costs (water and energy) should be minimized; it is important to define an ideal cooling regime, considering improvements in thermal comfort, animal performance, and environmental responsibility.…”

Evaluation of solar photovoltaic systems to shade cows in a pasture-based dairy herd

“…A THI of 68 to 72 has been reported to induce heat stress in cows and decrease milk production (Bohmanova et al, 2007;, decrease fertility (García-Ispierto et al, 2006), and increase lameness in dairy cattle (Cook et al, 2007). Prior research has been conducted on heat abatement measures in freestall barns with sprinklers, evaporative cooling, and fan design (Chen et al, 2015;Drwencke et al, 2020). However, pasture-based research efforts on heat abatement are limited and have investigated fabric and trees for shade and sprinklers (Tucker et al, 2008;Schütz et at., 2009;Palacio et al, 2015).…”

Sampling strategy and measurement device affect vaginal temperature outcomes in lactating dairy cattle

“…To address objective 1 (logger comparison), we conducted a prospective study using VT data from 54 cows enrolled in cooling trials to minimize animal use (Tresoldi et al, 2019;Drwencke et al, 2020). In 2016, we sampled 23 Holstein cows, averaging 36.7 ± 3.8 kg of milk/d, 223 ± 56 DIM, 2 ± 1 lactations, and 95 ± 52 d pregnant.…”