Is it true that zebras can’t see the colour orange,if so why not?

Question: Is it true that zebras can't see the colour orange,if so why not?
- Keywords:
  colour,
  colour blind,
  fact or fiction,
  orange,
  sight,
  vision,
  zebra
Asked by amy98 to Jo, Kevin, Louise, Valeria on 20 Jun 2012.
- Kevin Mahon answered on 20 Jun 2012:
  
  Zebras do have excellent eyesight and it is believed they can see in colour, but like many animals, they cannot distinguish between certain colours, in this case they can’t discriminate orange, and many other colours.
  
  For the life of me I can’t figure out why exactly it’s so widespread that zebras specifically cannot see the colour orange – this isn’t something unique to the zebra at all!
- Joanna Cruden answered on 22 Jun 2012:
  
  It seems to vary between people, many non primate animals are colour blind but it is one of the many unanswered zebra questions we have

Question: Is it true that zebras can't see the colour orange,if so why not?