Cows not all black and white
Research on colour vision in farm animals shows that they are dichromats with cones (colour sensitive retina cells) most sensitive to yellowish-green and blue purple light.
Humans are trichromats and see the full colour spectrum.
Dichromatic vision may make the animal more sensitive to seeing sudden movement. It may explain why grazing animals such as cattle balk at drain gates, shadows, and anything that has high contrast of light and dark. The brain�s fear centre which is called the amygdala is activated when an animal sees sudden movement.
One of the most common causes of balking in a handling facility is a small loose chain end that makes a rapid movement. Loose chain ends must be removed from races, chutes, and alleys. This is why people working with livestock should have slow deliberate movements. Grazing animals have a visual system that provides excellent distance vision but relatively weak eye muscles inhibit the ability to focus quickly on nearby objects.