Dairy cows do not like hot or humid weather. They will much prefer cool weather. The cows will dissipate body heat by panting but their ability is limited. When temperature is too hot, the cows will experience heat stress. This will cause lower feed intake and lower milk production. Death is possible in some cases.
Here are some tips to cool the cows:
1) Make sure sufficient water is available at all times. Heat stressed cows require double the amount of water than usual
2) Make sure there is shade in both the milking parlor holding pen and the housing area for both milking and dry cows.
3) Try to minimize the walking distance to parlor.
4) Minimize standing time in the holding pen.
5) Improve air ventilation for the cows in holding pen or free stalls.
6) Provide cooling for closeup cows, fresh cows as well as mid and late lactation cows in the housing areas.
Cooling cows will definitely help to boost the cow's performance. It is an investment that pays long term dividends. Work with your team and come up with a plan to cool the cows.