I recall the commercial differently. It had a background rhythm track and today might be considered an early rap song.

How now brown cow, what's new with you?
What's new you ask, well can I moo,
It's Milko, Milko, instant chocolate Milko.
Tastes smooth and creamy like chocolate oter,
And listen to this, you just add water
To Milko, Milko, instant chocolate Milko.
So take a tip from the old brown cow,
You'll love chocolate Milko, better get some now.
That's Milko, Milko, instant chocolate Milko.

This was heard in Ottawa, Canada in the late 50s or early 60s.