Cooling cows with sprinklers: Effects of soaker flow rate and timing on behavioral and physiological responses to heat load and production

Abstract

Spray strategies (e.g., flow rate and spray timing) may affect the surrounding microclimate and how cows use soakers, affecting cooling efficiency. Our objective was to evaluate the combined effects of spray timing (i.e., frequency, low: 3 min on, 6 min off; or high: 1.5 min on, 3 min off) and flow rates (3.3 or 4.9 L/min) on behavioral and physiological responses to heat load and production in Holstein cows managed in a freestall barn. In a 2 × 2 Latin square design, 3 cohorts of 4 pairs of cows averaging (±standard deviation) 36.7 ± 5.4 kg/d of milk were tested for 3 d/treatment. Water was sprayed at the feedline from 0815 to 2330 h when air temperature and relative humidity averaged 27 ± 3°C and 37 ± 7%, respectively. The overall quantity of water sprayed was not affected by spray timing; it varied only as a function of flow rate. Cows' posture and location within the pen were measured continuously, whereas feeding and body temperature were recorded every 3 min over 24 h/d. Respiration rates were recorded daily every 45 min from 0900 to 2000 h. Neither spray timing nor flow rates affected posture, location in the pen, feeding activity, or respiration rates. Overall, on average, cows spent 12.6 ± 0.4 h/d lying down and 5.8 ± 0.3 h/d in the feed bunk area. While in the feed bunk area, cows spent 78 ± 3% of their time feeding. Average respiration rate ranged from 57 to 59 ± 3 breaths/min across treatments. Although body temperature tended to be reduced when using higher flow rate, this difference was 0.1°C when comparing 24-h averages (4.9 vs. 3.3 L/min: 38.6 vs. 38.7 ± 0.1°C). Body temperature differences, however, were more marked and statistically different when soakers were cycling, especially between 1100 and 2200 h. Despite this, the magnitude of the hourly differences were <0.2°C. Milk production also tended to increase by 1.5 kg/d when using higher flow rates. When using the same water volume, spray timing did not affect cow behavior, physiology, or production. Flow rate had a small effect on milk production and body temperature but the biological relevance of these differences is unclear, especially in this situation where all cows were relatively cool.

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

“…Cows spent an average of 12.3 h/d lying, which is comparable to the 12.5 h/d observed from previous work conducted by our team (e.g., Chen et al, 2016;Tresoldi et al, 2019). As heat load increases, cows spend less time lying down (Cook et al, 2007;Schütz et al, 2010;Chen et al, 2016), which would prevent conductive cooling via the freestall surface.…”

“…The time spent near the feed bunk was comparable to the 7.8 h/d observed by Chen et al (2013). However, it was greater than the 5.2 to 5.8 h/d observed in other studies (DeVries et al, 2003;Tucker et al, 2006;Tresoldi et al, 2019). These differences may be a result of climate conditions or the amount of time heat abatement was offered at the feed bunk.…”

“…These differences may be a result of climate conditions or the amount of time heat abatement was offered at the feed bunk. Chen et al (2013) offered spray water 24 h/d, and Tresoldi et al (2019) offered spray water on a fixed schedule from 0815 to 2330 h. Heat abatement in our study was triggered by AT, which did not always drop below the threshold at night (Table 3). For example, the mean amount of time the spray water was triggered by AT was ~15 h/d but ranged from about 4 to 24 h/d.…”

Invited review: Lying time and the welfare of dairy cows

“…Numerous studies consistently report that, as ambient temperatures increase in summer, dairy cows spend less time lying down (Shultz, 1984;Wagner-Storch et al, 2003;Cook et al, 2004Cook et al, , 2007Zähner et al, 2004;Tapkı and Şahin, 2006;Tucker et al, 2008;Schütz et al, 2010bSchütz et al, , 2020Legrand et al, 2011;Chen et al, 2013Chen et al, , 2016aMattachini et al, 2017;Tresoldi et al, 2019), regardless of provision of heat abatement (Overton et al, 2002;Legrand et al, 2011;Chen et al, 2013Chen et al, , 2016a. Both Chen et al (2016a) and Tresoldi et al (2019) found that daily lying time is reduced by 21 to 22 min for every 1°C increase in ambient temperature, within the range tested, whereas King et al (2016) report a more modest 15-min reduction for every additional 10°C. Fewer studies have examined the effects of winter weather.…”

Artificial Intelligence Applied to a Robotic Dairy Farm to Model Milk Productivity and Quality based on Cow Data and Daily Environmental Parameters

“…Physical modification of the environment to reduce ambient temperature or increase heat loss from the animal body, such as shading and fans, have been previously applied for lactating buffaloes with positive results [29], and in dairy cows using mixed-flow fans [30]. However, one of the most effective methods found is spraying water over animals using sprinkler systems [31][32][33][34]. This paper proposed the implementation of Model 2 with an automated system based on an individual cow assessment combined with environmental factors obtained from an automatic meteorological station (AME) (Figure 4).…”