Cows lactate only when they have recently given birth, just like humans. For this reason cows are kept constatly pregnant so that they would give birth as often as possible. If the same was done to dogs, the dogs would be taken away from their owners due to exploitation.
Because humans want to continue breastfeeding as adults, the calves are taken away from their mothers after birth. Otherwise the calves would consume the milk and there would not be enough for humans.
Dairy industry kills. Male calves are killed for veal. Female calves have to endure the same treatment as their mothers before they are killed. They have to be constantly pregnant, lose their babies after birth, and in a few years they are killed for burgers.
Cows are supposed to grow 4 times faster than humans. Human bodies cannot handle this speed of cell growth, especially after being weened from their own mother's milk. This is why in grown up humans milk causes growth of cancer.
Digestion of dairy causes the formation of compounds called casomorphins. They are about 1/10th of the strength of actual morphine. Because of the opioid properties, dairy products are addictive to many people. The purpose of casomorphins is to motivate the babies of mammals to return to breastfeed from their mothers again and again.
Cow's milk casomorphins are about 10 times stronger than human milk casomorphins. That's why so many humans crave milk, cheese, ice cream and so on made of dairy.
Pasteurization of milk only kills micro-organisms. The harmful hormones, pus, blood and antibiotics are still in dairy when humans consume products made of it.
