Effects of adjustable and stationary fans with misters on core body temperature and lying behavior of lactating dairy cows in a semiarid climate

Abstract

Cows readily seek shade to reduce solar heat load during periods of high ambient temperature. Typically, auxiliary cooling systems are oriented to maximize cooling for shaded cows. However, when a shade structure is oriented north-south, stationary fan and mister cooling systems are unable to track shade as the sun's angle shifts throughout the day, and thus can become ineffective. The FlipFan Dairy Cooling System (Schaefer Ventilation Equipment, Sauk Rapids, MN) employs fans and misters that follow shade and compensate for wind speed by rotating on a horizontal axis. Multiparous, lactating Holstein cows (n=144) on a commercial dairy in Arizona were cooled by a fixed system comprised of stationary fans and misters acting as control or the adjustable FlipFan operated for 16.5 h/d (0830 to 0100 h). Core body temperatures (CBT) of 64 cows (4 pens/treatment; 8 cows/pen; 6d) and lying behavior of 144 cows (4 pens/treatment; 18 cows/pen; 5d) were collected by intravaginal and leg data loggers, respectively. Cows were balanced by milk production, blocked by days in milk, and randomly assigned to pen within block. Pen was the experimental unit. In a second experiment, isothermal maps were developed using a fixed system of thermal data loggers arranged in the shaded areas of the pens at different times of day and were analyzed for differences in the temperature-humidity index (THI) achieved by each cooling treatment. Ambient conditions consisted of a mean temperature of 33.0°C, mean relative humidity of 40.3%, and mean THI of 80.2. Mean 24-h CBT for FlipFan was lower than control (38.9 vs. 39.1±0.04°C). A treatment × time interaction was observed in which CBT of FlipFan was 0.4°C lower than control from 0600 to 0800h and 1500 to 1600h. Cows cooled by FlipFan spent more time lying down compared with those cooled by control (9.5 vs. 8.6 h/d). Cows under FlipFan had more frequent lying bouts than did those under control (12.8 vs. 10.7 bouts/d). Lower CBT and decreased standing time are consistent with the findings of other studies when ambient heat load was reduced. In the second experiment, the FlipFan system achieved a lower THI in the morning and evening (5.9 and 1.7%, respectively), and the THI also tended to be 0.8% lower in the afternoon compared with that of control. Results indicate that FlipFan is more effective than a stationary fan and mister system at decreasing CBT, increasing lying time and bouts, and providing a more desirable microenvironment for cows throughout the day in a semiarid environment.

Relationship between THI level and dairy cows’ behaviour during summer period

“…On commercial farms the lying time can be used as a measure of a cow's welfare (Vasseur et al 2012). This is particularly important in the case of heat stress, which reduces the lying time (Anderson et al 2013). It was also confirmed in research performed by Cook et al (2007) in which with increasing of THI the lying time was reduced by 3 h. Along with the deteriorating microclimatic conditions also decreases the locomotor activity (West 2003).…”

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

“…The absence of an effect of access to shade on total time spent standing and lying was unexpected as some studies reported increase in time spent standing to increase heat dissipation by convection (Anderson et al, 2013) while others (Tucker et al, 2008;Schütz et al, 2010) have reported that increased standing time is partly attributed to insufficient cow shade. This was not the case in the present study as cows had more than 10 m 2 each of available shade.…”

Practices for Alleviating Heat Stress of Dairy Cows in Humid Continental Climates: A Literature Review

“…Misting systems were used with good success in the US (Arizona, Kansas, and California) and Saudi Arabia where humidity is typically low [62,63,64,65,66]. Numerous studies [67,68,69,70,71,72,73,74,75] compared the environmental conditions and physiological responses of dairy cows under misters with those obtained under an open-sided barn alone or equipped with fans (Table 6).…”