The milk of each species, was design by God for the 'young of that species' and not for any other species, nor for the adults of any species.
The milk from a cow was designed by God for calves and not for goats or colts or any other species. Other species can survive and grow to adulthood on the milk of another species but 'not as well' as the milk from their own species.
Now concerning human adults consuming milk:
When was the last time you saw a cow, suckle on another cow's tits or a mare's tits? You would be rather shocked if you did see that happen.
Why? Because this is not the natural thing to do. In nature, it is unnatural for any adult 'of any species' to consume the milk of any species.
So why does man drink milk 'as an adult' and also drinks the milk of another species (a cow) and not his own species (a woman)? A man certainly would not suckle on the tits of a cow or the breast of a human female for milk.
Concerning natural milk and unnatural milk. The milk produced by an animal is 'natural' as long as that animal consumes food and water that it would consume in the wild that God created for it, specifically vegetation that grows up from the ground in the form of grasses, weeds, herbs etc. and is not injected with hormones or drugs of any kind and is not heated or altered in any way. When humans consume milk from animals in this condition, it becomes basically a wholesome and healthy food when consumed along with a vegetarian diet.
Remember, all animal food has NO fiber and therefore can contribute to constipation. Milk is a 'liquid solid' and when made into cheeses those become very constipating. That is the reason a person consuming animal foods definitely should include raw nuts, raw vegetables, raw fruits, raw seeds and legumes in their diet because all of these are high in fiber.
The milk and flesh from an animal becomes unnatural and quite unhealthy when animals are fed an unnatural diet and pumped full of antibiotics, drugs, hormones, etc. and even worse when the milk from these animals is heated to kill enzymes and other forms of nutrition and then homogenized to make a 'product of a factory' instead of a 'Creation of God'.
Man will never be smarter than God but instead keeps screwing up what God has made.
We are told by the Dairy Industry that 'milk does a body good'. That's true as long as it is milk that in NOT produced by the Dairy Industry. The only milk and milk products fit for human consumption is that which comes from cows raised on organic food that is natural to them and where none of the milk or products were made where heat was applied. Also, the farmer producing that milk and products must follow very clean practices so that none of that milk or milk products becomes contaminated by feces and also not allowed to stay warm but put under refrigeration soon after milking.
I spent four of my teenager years from age 12 to 16 on a family farm in Wisconsin just a short distance from Knapp. When driving from Knapp to Menomonie, look on your right and when you see a long county road going back to a farm, with a hill to the left of the barn, that was our farm. My parents paid $5,000.00 cash for that farm in 1945.
Cows will sometime lay down on manure getting that on their udders and tits. Before we ever started milking any cow, we cleaned off the udders and tits to make sure they were clean before we would milk them. Also, as soon as a milk can was full of milk, it was place in a big water tank to cool it down. This was way back in 1945 thru 1949 and no farmer had walk-in refrigeration at that time. None of us ever got sick from that milk or the buttermilk and cheeses my mom made from that milk and that was two adults and five kids.
To hear the Dairy Industry tell it, humans need milk for strong bones, teeth and on and on. If milk was so necessary for health, then why don't cows drink milk? When eating grass, weeds and herbs they do just fine and end up with strong bones, teeth etc. As a matter of fact, some of the largest and strongest animals on earth are vegetarians. You will say that we humans can't digest grass that animals eat, which is true, but there are many different kinds of grasses and it is a well know fact that cereal grasses, like wheat grass is actually a [super food] ingested by millions all over the world.
Man will never be smarter that God.
How can the [Created] be greater that the Creator?
Is a house greater than he who built it?
Our Creator is 'Infinite' we are finite.
We are limited, He is not Limited.
We are at a certain place at a certain time. He is everywhere at the same instant.
We only know our own thoughts, he knows everybody's thoughts at all times.
We can travel at certain speeds to where we want to go. He is everywhere at all times.
He is the LIFE in all of us and every living thing in all the Universe.
We live on a certain planet called the Red Star. He is the power that created the planets in all the Universe that are so many, they are without number.