* Pigmentation: Cows have pigments in their skin and hair called melanin. These pigments come in different shades, and the combination of melanin types determines the cow's color. Most cows have a combination of black and brown melanin, leading to a variety of shades from black to brown to white. Pink is not a common color produced by melanin.
* Evolutionary Adaptation: Cows evolved in environments with varying temperatures and sunlight. Their color helps them to regulate their body temperature and camouflage from predators. Pink would not be as effective in either of these roles.
* Selective Breeding: Humans have selectively bred cows for specific traits, including their color. Farmers prefer certain colors for various reasons, but pink has not been a common selection.
It's important to note that there are rare genetic mutations that can lead to pink cows. However, these are extremely uncommon.