Sprinkler system in a holding pen: Behavioral responses of dairy cows during the subsequent grazing

Our objective was to evaluate the effects of cooling systems in a holding pen and its effects on the behavioral responses of pasture-based daiiy cow. The experiment was performed during February and March, 2014. Thirty-six black and white Holstein cows (BW = 527 ± 49 kg) were used in a crossover design (6 x 3). The cows were divided into groups of two animals (w = 18 groups) and each group was acclimated for 3 d following 6 d of data collection (2 d/treatment). The treatments used were: (1) control: no cooling. (2) sprinkler with media flow (MF): 0.08 L of water/nozzle/min. and (3) Sprinkler with high flow (HF): 1.00 L of water/nozzle/min. The sprinkler cycle included 30 s of water spraying and 60 s turned off. Cows were milked twice daily (0630 h and 1430 h) and treatments were applied during 20 min before each milking. After the milking routine, dairy cows were allowed to graze as a single herd. Environmental variables air temperature (AT), relative humidity (RH). black globe temperature (BGT). temperature humidity index (THI). and heat load (HLI) were recorded in a holding pen. in a pastured area and under the natural shade present at the grazed area. The dairy behavior (posture, location, and activity) was monitored from 0800 to 1230 h and from 1530 to 1800 h eveiy 10 min. Panting score (PS) was evaluated each 15 min. The difference in water flow used in sprinkler systems reduced (P < 0.01) HLI and THI iii a holding pen. However, spiinkler sstems did not change behavioral patterns of dairy cows on pasture. The lowest PS average occurred at 0800 h (0.04) and highest at 15 h (0.75). PS was positively correlated (p = 0.94) with the THI under the shade, and it was negatively associated with the time spend on the paddock (p = -0.63). Cows were obseived 50% of the time in rest activity, followed by glazing activity (25%). rumination (14%). other activities (9%). and drinking water (2%). The HLI was negatively correlated (p = -0.82) with the percentage of time spent on glazing. Cows spent 89% under natural shade during the hottest hours. The results demonstrate which evaporative cooling system used in a holding pen has immediate and short-term effect on dairy cows.