When dry cows are cooled with fans and sprinklers during warm weather, they produce more milk in their subsequent lactation, research has shown.
In one study, researchers from the University of Florida observed an increase in the proliferation of mammary cells in cooled cows during the transition period. Cooling was applied 46 days before expected calving. The study can be found in the December 2011 Journal of Dairy Science.
Some of the same researchers reported in the December 2009 Journal of Dairy Science that there was a 16.5-pound difference in milk yield (74.3 pounds per day versus 57.76 pounds per day) in the subsequent lactation among dry cows that were cooled versus cows that weren't. The different was even greater — 20.5 pounds — when stated as 3.5 percent fat-corrected milk yield.