If your border collie is black and white, the sheep will think the dog is just another sheep. They need to be both black and white because sheep can be black or white (reference the song "Baa Baa Black/White Sheep).
If they are merle, the sheep will think they are being chased by a mangy hyena.
You send Bean here. I'll send you Gusto, who is appropriately colored but half terrier. Oh dear. You'll have a sport mix, and the sheepdog people will hang you from a higher tree. You're screwed either way. Might as well enjoy the ride.