Why Shepherds?

So I Remembered something yesterday that I had forgotten for a while. It was something I learned in my institute class over the summer. Does it seem strange to anyone that God would send angels to the shepherds to announce the birth of his son? Well one of my instiute teachers explained why God did that.

If I remember right he said that the shepherds were of the tribe of Levi. And the shepherds were responsible for witnessing the births of the first born males in the flock. They would verify that it was without blemish and then the lamb could be used for sacrifices. Well with that knowledge it makes sense that he would appear to the shepherds so they could claim him to be the son of God, the first born male, with out blemish and ready to be sacrificed. Pretty cool.