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.