This has proved to be very taxing. These are teeth from an extinct species of Giant Warthog which are reported from the piocene and pleistocene of Africa. There are a number of species including Kolpochoerus majus and Metridiochoerus modestus, goole image searches of these will produce photos of very similler teeth.
My name is Ms Helke Mocke and I work in the Museum of the Geological Survey in Windhoek. I have been contacted by a fossil pig/warthog expert who saw your post on the fossils you found on your farm and he would like to study the items. Could you please contact me at 061 2848391 or email me at email@example.com.