The hormone responsible for milk let-down in cows is

The hormone responsible for milk let-down in cows is oxytocin. Oxytocin is produced in the hypothalamus and stored in the pituitary gland. When a cow is stimulated by the presence of her calf or milking machine, oxytocin is released into her bloodstream. Oxytocin causes the muscles around the alveoli (tiny sacs within the mammary gland) to contract, pushing milk into the larger ducts and out of the teat. This process is known as milk let-down or milk ejection. Oxytocin is also known as the "cuddle hormone" because it is released during social bonding activities, such as hugging or touching, in humans and other mammals.