I saw a dead cow on the roadside after it had been killed by a vehicle
late at night, could that be a bad Omen, if so what could it mean?

It's fairly difficult to hit a cow standing in the middle of a road,
considering how slowly they move. I think the fact this happened means
there is one very bad driver on that road.

I happen to know someone that has done this. He's a great musician,
but a very bad driver. He has also locked his keys in his truck when
he went inside a 7-11 store. The funny part is the truck was running!

Only for those silly enough to be superstitious.

If I were a cow, I'd probably consider this sort of thing to be a bad omen.

LMAO, pink..., I was drinking coffee!

Cynthia,
Quite to the contrary, it is very easy "to hit a cow standing in the
middle of the road, considering how slowly they move."  But is not to
be recommended.

If it is an omen,  I doubt it, just a warning to be on the watch for
free ranging cattle, espcially at night; they are blinded by your
headlights.
Myoarin

myoarin, indeed, at night I can surely understand. My friend Karl hit
the cow on a very long, straight, and level road, in broad daylight.
You could see the cow for a couple miles before he got to it. My
reference to how slow they move pertained to [slowly] driving around
the non-moving cow, but now that you mention it, it makes much more
sense the way you stated it!

~~Cyn

I cant believe you left all that fresh beef-steak just lying there for
the next person to pick up :)

After a couple of days of deep thought about omens and the fact that
they are part of some religions, I have decided that the cow was a
Hindu reincarnation (I don't believe there is anything that says that
beings must be reincarnated in the same area or on the same
continent), and that it assumed that it was a holy cow and had nothing
to fear (see opening chapter of Kipling's "Kim"), and perhaps it also
was unhappy about finding itself on the wrong continent, so with its
faith in reincarnation it had no problem with being given a chance to
return.
(No offense intended to any Hindus reading this!)

Cynthia:  Greetings to Karl, I have done that twice!  Once in an
underground garage, the second time in a traffic jam on the Autobahn
(but by then I had learned to pop the rivet on lock of the hinged rear
window  - entertainment for all  :-/ ).