This controls blood flow and milk production . Other nerves send messages from the udder and other parts of the body to the brain about touch, temperature and pain. The body then releases hormones which also control blood flow and milk production. This helps milk let-down . 36 Excitement and pain also send messages to the brain.
Glands release another hormone epinephrine which reduces blood flow and milk production.
The Lymph System Lymph ducts drain colourless fluid from tissues into the blood vessels. You can feel some of the lymph nodes through the skin. They are part of the cow's immune system and help fight disease . 39 Near parturition, the lymph ducts cannot drain enough fluid from the udder which swells more than normal. This is called udder edema .