Table 2 summarizes the benefits observed with cooling systems made of sprinklers and fans in several experiments conducted in the United States. Researchers from the University of Missouri-Columbia (Igono et al., 1985) placed two lines of sprinklers in the freestall, one on top of the feed bunk, the other in the alley between the cubicles and the side wall. Sprinklers were set in cycles of 30 min. (20 min. on; 10 min off). Although they were able to reduce rectal temperatures, they only improved milk production by 1.6 pounds (52.7 pounds produced in the treatment group). A year later they repeated the experiment, this time with the addition of forced air on the top of feed bunk and cubicles; in this instance, milk production increased by 4.4 pounds per day (Igono et al., 1987). This demonstrated that increasing the air movement through the animals that have been soaked increases heat dissipation through the skin.
Intake and milk yield improved by 2 pounds per day when sprinklers were installed on top of the feed bunks in another experiment conducted in Alabama. In this experiment, the sprinklers were working in cycles of 15 min. (3 min. on; 12 min. off). Each treatment had fans both at the feed bunk and cubicles. It was determined that the fans alone did not improve cow comfort. The Missouri and Alabama experiments suggest that during severe heat stress, treating cows with sprinklers or fans exclusively is not enough and that both strategies need to be combined to reduce body temperature below 102.4°F.
A series of studies conducted at Kansas State University evaluated the efficacy of different cooling systems to alleviate heat stress. In the first experiment conducted during the summer, three different combinations of sprinklers and fans were evaluated in barns with four rows of cubicles. All the systems had sprinklers on top of the feed bunk programmed in cycles of 15 min. (3 min. on; 12 min. off). One treatment (2S) had two rows of fans on top of the cubicles, another treatment (F+S) had one row of fans on top of the cubicles and another on top of the feed bunk, and the last treatment (F+2S) had two rows of fans on top of the cubicles and one row on top of the feed bunk. Although there were no differences in intake between treatments, differences in milk yield were observed. The cows that were cooled with fans on top of the cubicles and the feed bunk produced more milk than those cooled with fans only on top of the feed bunk (93.9 vs. 98.8 pounds per day). There was no production response when the number of fans on top of the cubicles was doubled (F+2S). In a subsequent experiment (Brouk et al., 2001; Table 2), two cooling systems were evaluated, both with sprinklers and fans on top of the feed bunk but only one of them had a line of fans on the cubicles (F+S). It was confirmed that when the fans on top of the feed bunk were complemented with those on top of the cubicles, milk yield increased by 5.8 pounds per day. Based on the results of these two experiments, the authors concluded that the most effective cooling system for barns with four rows of cubicles was having sprinklers on top of the feed bunk and two rows of fans, one on top of the cubicles and another on top of the feed bunk. However, the results differed for barns with two rows of cubicles and sprinklers on top of the feed bunk (Brouk et al., 2001; Table 2). For these facilities, the best cooling system was a row of sprinklers on top of the feed bunk and one row of fans on top of the cubicles (S). An additional row of fans on top of the feed bunk did not improve milk yield. Barns with two rows of cubicles are narrower than those with four, which allows for better natural air circulation.