I've heard: " cows" , I've heard " ka-os" , but the actual correct way is " k" , we pronounce the " a" as a diphthong, as like a two-vowel sound, " ke yos" or " key os" .
They are clear sounds similar to what we see in Spanish or in, uh, Japanese, for example, where they have five sounds: ka ki ku ke ko, five vowel sounds.