They are not. Cattle (cows and heifers) are bred either via artificial insemination, or natural breeding.
artificial selection
In order to give them optimal traits that will make them more resistant to disease and sickness.
Artificial selection.
artificial selection artificial selection
as cattle-driver
artificial selection
In order to give them optimal traits that will make them more resistant to disease and sickness.
Artificial selection.
Artificial selection.
Artificial selection and selective breeding.
They were bred for herding cattle.
Directional selection can be used by artificial means as well. This can be seen is "pure bred" cats, dogs, horses and many others.
bred (As in you have bred the cattle)
Angus cattle
Natural variation, natural selection, artificial selection, genetic engineering, etc.
They were first bred to herd cattle.
In some cases, the direction of evolution is intentionally controlled by humans. We call this artificial selection, or breeding - as in the breeding of cattle. In all other cases, nobody controls the direction of evolution.