We humans experience "heat stress" at high summer temperatures and/or high humidity, which challenges our circulatory system. For cows as "suppliers" of milk, cream, yogurt, the level of heat stress is much lower than for us bipeds, because their metabolism is working hard to convert grass, grain or corn into milk. This generates a lot of heat, which cows can poorly dissipate through their skin (leather).
Cows feel comfortable at -5 to +20° C; above these temperatures stress begins for them and we can use Lechler nozzles to ensure that they are well - also in the interests of animal protection. The consequences of heat stress are less feed intake, less movement of the animals and also a lower production of milk, with higher costs for the farmer.
In addition to large fans to cool the animals, nozzles are also used to increase the cooling effect.