Thanks for the picks Za Zjurman, they don't look half bad considering they are just toys. The scale is good for smaller cattle too.
I don't remember this being mentioned before, but if you are looking for some visual inspiration for actual cattle (for paint jobs and what not) there are several rare breeds organisations out their.
The Livestock Conservancy in the US and the
Rare Breeds Survival Trust in the UK have good sites (for all farm animals not just cattle).
Seeing the work of organisations such as those highlights the difficulties in tracking the history of farm animals. Until the 18th century no one really took livestock breeds seriously, so records early than that tend to be incidental rather than deliberate. If nothing else they give a general idea of how cattle may or may not looked throughout history. As most people have worked out, they tend to be smaller, thicker set than modern dairy cattle, hairier and have bigger horns. No surprises there.
@Argonor: I can't see why Longhorns painted up the right colour wouldn't be a perfectly acceptable stand in. Make sure you post pictures so that we can see how it goes.