COMPARISON OF VARIOUS FAN, SPRINKLER, AND MISTER SYSTEMS IN REDUCING HEAT STRESS IN DAIRY COWS

Heat stress in dairy cows causes large losses of milk production, but such declines can be lessened if the cows are cooled. Two two-year experiments were conducted during four summers to evaluate the effectiveness of various fan, sprinkler and mister systems on cow performance and their environment. Cow housing, if provided, was in an open-sided, well-vented free-stall facility. In experiment 1, cows were either outside much of the time, inside with fans only or inside with fans and intermittently sprinkled with water. The afternoon air temperature was lower in the sprinkled area and the cows on the sprinkled treatment had greater dry matter intake and milk production during one summer than for cows on the other treatments. Cows allowed outside produced as well or better than cows left inside with fans only. In experiment 2, cows were assigned to treatments in which control cows had limited time inside with fans while other cows were inside with fans only, fans plus intermittent sprinklers, or fans plus misters. Inside areas with sprinklers or misters were cooler than with fans only. Cows assigned to areas with sprinklers or misters had lower respiration rates and consumed more dry matter than cows inside with fans only or allowed access to the outside. Cows sprinkled gave more milk during the first summer than those on other treatments, but mist in the fan plus mister area was caught in up-drafts and did not reach the cows. Milk production did not differ during the second summer for cows on sprinkler or mister treatments when the misters were lowered to prevent mist up-drafts. About 10 times more water was used for the sprinkler than the mister treatments during each of the two years. Proper use of water to cool cows in hot weather reduced milk production loss.