This is a important consideration in planning fences as most mammals are two-colour (dichromacy) which are unable to distinguish between green, yellow, orange and red . The straight forward exceptions are some primates and humans, which are usually three-colour vision (trichromacy) Birds and various other non-mammalian vertebrates do human vision one better, by being able to see in four colours (tetrachromacy); many birds can also see in the the near-ultraviolet.
This important as the view of the human does not reflect the vision of the livestock, feral and native fauna.
Typically it is accepted that white is the most visible to dichromats , the Equine management has adopted this practice widely. Contrasting colours to the background and that are Luminescent in low light giving stand out qualities.
Simulation software can show the difference between Human and Livestock vision in respect to colour , this is a very useful tool when determining the correct fence for the application as the visual effect of the fence is the primary response of the boundary.
Below Left Normal Human Vision and Right livestock vision (dichromat)
Please note that if you do not see the difference or a significant difference you may be the 10% of the population that has colour vision impairment (mostly males)