Photopigment basis for dichromatic color vision in cows, goats, and sheep.

Electroretinogram (ERG) flicker photometry was used to measure the spectral properties of cones in three common ungulates-cattle (Bos taurus), goats (Capra hircus), and sheep (Ovis aries). Two cone mechanisms were identified in each species. The location of peak sensitivity of an S-cone mechanism varied from about 444 to 455 nm for the three species; analogous values for an M/L-cone were tightly clumped at about 552-555 nm. Each of these three species has the requisite photopigment basis for dichromatic color vision and they are, thus, similar to other ungulates examined earlier.