That's the way humans or "man" selected them to be: to be used for food in the form of meat and milk, for clothing from the hides, manure to be used on fields and gardens, as well as a useful labour-free tool of keeping the grass down wherever need be without having to turn on the lawn mower or use a scythe.
they give milk
Typically in American English the statement would be "a cow is a useful animal" - the first sound in useful is close enough to a consonant that most individuals will use "a" rather than "an".
we use cow to get milk
Humans.
it can be turned into a beverage (milk), and whipped into cream for butter, and cheese (i think). Its useful cause its a food/drink source and not only somewhat tasty but also healthy with calcium and other important vitamins/nutrients.
ox, lizard,cow,...
Snakes don't help humans..but they are useful for entertainment..but are dangerous.
its not useful for the refrigerator its useful for humans only....
"Cow meat" -- aka Beef -- gets eaten by humans.
Yes.
No. tapeworms are pest to humans.
Near the liver and the stomach, just like in humans.