Playd tru 1 time and hunted all animals but coud not get the achivment. Lookt at the list and was missing the cattle (cow) Lots of bulls no cows. Started all over after 100% complet story and went looking for cows and stil non on the Hole map.
Also at the end of the Nick Rye mission (you can get out of the plane, kill the cow in the dock and then go back to the plane and drive it into the dock).