Bulls can only see two primary colors: blue and green. Bulls are unable to see red or orange, which appears to them as shades of green or gray. This limited color vision is similar to the color vision of dogs and cats but differs significantly from humans, who have a trichromatic vision and can see a much broader range of colors.

Bulls only have green and blue receptors but lack red receptors. Besides grey and black, bulls can see colors in the yellow and blue spectrum with lower intensity and vibrancy. Their color palette is not as rich as human beings, therefore, they can not see all shades of yellow and blue.

Besides not seeing red, a bull’s vision isn’t all that different from a human’s. Like dogs, yellow and blue are the colors that appear most vibrant to them. Purple, black, and gray are some other colors that bulls can see somewhat well.

In fact, bulls are partially color blind compared to healthy humans, so that they cannot see red. According to the book "Improving Animal Welfare" by Temple Grandin, cattle lack the red retina receptor and can only see yellow, green, blue, and violet colors.