Hot environments for dry cows can risk their early lactation milk production. It is easy to concentrate cooling efforts on the producing cows and leave dry cows to a lower priority. However, research has shown that cooling dry cows can better prepare their metabolism and increase milk hormone sensitivity for a more productive lactation.

When cooled dry cows were compared with heat stressed dry cows in a cross-over experiment (meaning the same cows were exposed to the same barn, on the same feed and housing conditions but cooling and non-cooled systems were swapped over periods of time), it was found that circulating prolactin – the hormone driving milk production – was lower in the cooled dry cows, but their receptor expression was enhanced. This means that when they calved, they had more prolactin receptors available to receive the milk-producing hormone in early lactation. Reference in this link.

Dry cows are better prepared for lactation if kept comfortably cool!